China Shenzhen Perfect Precision Product Co., Ltd. company news

During the processing of the mold, it is necessary to follow the specified process in order to ensure the accuracy of the mold and product quality. Mold processing is a complex process, and we must make this process accurate when processing. What is the mold processing process? Let's talk about it in detail. The mold processing process generally includes: mold blank preparation - rough machining of parts - semi finishing - heat treatment - finishing - cavity surface treatment - mold assembly - machine commissioning. 1、 Mold blank preparation Most of the die blanks are metal. Taking forging as an example, the raw materials for forging are generally bars, plates and pipes. Operators mainly choose according to the specific shape and geometric size of the blank. For sheet blanks, ordinary blanking or precision blanking can be used. If it is necessary to forge the annular parts, the pipe can also be used to cut the blank. 2、 Rough machining of parts For rough machining of parts, we take milling as an example. As long as the outline and island of the part are given, the machining path can be generated. And the arc can be automatically added at the sharp corner of the track to ensure that the track is smooth, so as to meet the requirements of high-speed machining. It is mainly used for milling planes and grooves. Multiple contours and islands can be selected for processing. 3、 Semi finishing The semi finishing stage is to complete the processing of the secondary surface and prepare for the finishing of the main surface. 4、 Heat treatment Heat treatment is a comprehensive process in which materials are heated, insulated and cooled in a certain medium, and their properties are controlled by changing the surface or internal structure of materials. The heat treatment process generally includes three processes: heating, insulation and cooling, and sometimes there are only two processes: heating and cooling. These processes are interconnected and uninterrupted. 5、 Finish machining The machining allowance of finish machining is smaller than that of rough machining. Select good props for cutting, control the walking speed and rotation speed of props, and pay attention to the size and gloss appearance of materials. 6、 Cavity surface treatment Different surface treatment methods of the mold can change the chemical composition, structure and properties of the mold surface, and greatly improve the surface properties of the mold. Such as hardness, wear resistance, friction performance, demoulding performance, heat insulation performance, high temperature resistance and corrosion resistance. This step is of great significance for improving mold quality, greatly reducing production costs, improving production efficiency and giving full play to the potential of mold materials. 7、 Mold assembly According to certain specified technical requirements, the process of assembling parts into components and combining them into components and even the whole machine. There are two forms of assembly, one is fixed assembly, and the other is mobile assembly. Different assembly methods are selected for different batch production. During the assembly process, some mold parts need to be polished and trimmed. The main content of mold assembly is to assemble the processed mold parts and standard parts into a complete mold according to the requirements of the mold assembly drawing. After the mold test, some parts need to be adjusted and repaired to make the parts produced by the mold meet the requirements of the drawing, and the mold can work continuously normally, so that the processing of the mold can be completed.

In order to meet various processing requirements, the processing of special grooves is also a part of machining production. Common special grooves include V-shaped groove, T-shaped groove and dovetail groove. The special groove is usually milled with a milling cutter with a cutting edge shape corresponding to the groove shape. So, what is the milling method of the special groove? Now let's introduce it in detail. V-shaped groove and its milling method 1. Main technical requirements of V-groove (1) The central plane of the rectangular groove shall be perpendicular to the datum plane (bottom surface) of the cuboid. (2) Both sides of the cuboid should be symmetrical to the central plane of the V-shaped groove. (3) Both sides of the narrow V-shaped groove should be symmetrical to the central plane of the V-shaped groove. The bottom of the narrow groove should slightly exceed the extended intersection line on both sides of the V-shaped groove. 2. Milling method of V-groove (1) Adjust the end milling head and mill the V-shaped groove with an end milling cutter: the V-shaped groove with an included angle greater than or equal to 90 degrees can be turned up in the vertical milling machine and milled with an end milling cutter. Before milling, the narrow groove shall be milled first, and then the end milling head shall be turned, and the V-shaped groove shall be milled with an end milling cutter. After milling the V-shaped surface on one side, loosen the workpiece, turn it 180 degrees, clamp it, and then mill the V-shaped surface on the other side. You can also turn the vertical milling head in the opposite direction and mill the V-shaped surface on the other side. During milling, the reference plane of the fixture or workpiece should be parallel to the transverse feed direction of the workbench. (2) Adjust the workpiece milling V-shaped groove: for V-shaped grooves with an included angle of more than 90 degrees and low accuracy requirements, one side of the V-shaped groove can be corrected according to the scribed line, so that it is clamped parallel to the workbench table. After milling one side, re calibrate the clamping on the other side, and then milling. When the included angle is equal to 180 degrees and the size of the V-shaped groove is not too large, it can be clamped and milled at one time. (3) Milling V-shaped groove with angle milling cutter: V-shaped groove with an included angle less than or equal to 90 degrees is generally milled on horizontal milling machine with symmetrical double angle milling cutter with the same angle. Before milling, narrow groove shall be milled with saw blade milling cutter, and the datum plane of fixture or workpiece shall be parallel to the longitudinal feed direction of workbench. If there is no suitable symmetrical double corner milling cutter, two single corner milling cutters with opposite cutting edges and the same specification can be used for milling. When assembling, a washer or copper sheet with appropriate thickness (less than the width of the narrow groove) should be placed between the two single angle milling cutters, or the cutting edges of the two single angle milling cutters should be staggered, so as not to damage the end edge of the milling cutter. 2、 T-shaped groove and its milling method 1. Main technical requirements of T-groove (1) For the dimensional accuracy of the width of the straight T-shaped groove, the reference groove is it8 and the fixed groove is it12. (2) The two sides of the straight groove of the reference groove shall be parallel (or perpendicular) to the reference plane of the workpiece. (3) Both sides of the bottom groove should be basically symmetrical to the central plane of the straight groove. 2. Milling method of T-shaped groove Generally, for the milling of T-shaped groove, first mill the straight groove with three edge milling cutter or end milling cutter, and leave an allowance of about 1mm for the depth of the groove, then mill the bottom groove with T-shaped groove milling cutter on the vertical milling machine, and mill the depth to the requirements, and finally chamfer the groove with angle milling cutter. The groove milling cutter shall be selected according to the width of the straight groove. The neck diameter of T-groove milling cutter is the basic size of T-groove. 3. Precautions for milling T-shaped groove (1) When cutting with T-groove milling cutter, the cutting part is buried in the workpiece, and the chips are not easy to be discharged. It is easy to fill the chip holding groove (plug the cutter) and make the milling cutter lose cutting ability, so that the milling cutter is broken. Therefore, the cutter should be withdrawn frequently and the chips should be removed in time. (2) When cutting with T-groove milling cutter, the cutting heat is not easy to emit due to poor chip removal, which is easy to cause the milling cutter to anneal and lose the cutting ability. Therefore, when milling steel parts, cutting fluid should be fully poured. (3) When cutting with T-groove milling cutter, the cutting conditions are poor, so smaller feed rate and lower cutting speed should be selected.

In mechanical parts, the connecting surface plays the role of connection, which is generally relative to a certain plane that has been determined. This topping plane is called the datum plane in machining. When machining the connecting surface, the datum surface should be machined first. Datum machining is a single plane machining. In addition to the requirements of flatness and surface roughness, the machining of the connecting surface also needs to ensure the position accuracy relative to the datum plane and the dimensional accuracy between the datum plane. Circular milling or end milling is often used to process vertical and parallel surfaces in machining. We have introduced circular milling before. This paper mainly introduces a drooping straight and parallel surface end milling method. 1、 Vertical face milling 1. Use flat tongs to clamp the end and mill the vertical surface End milling is used to mill the vertical surface of small workpieces. Workpieces are generally clamped with flat tongs, which can be carried out on vertical or horizontal milling machines. When milling with an end milling cutter, the clamping method of the workpiece in the flat tongs, as well as the factors affecting the perpendicularity and the adjustment measures are basically the same as when milling the vertical surface with a circumference. The difference is: when milling with a cylindrical milling cutter, the cylindricity error of the milling cutter will affect the perpendicularity and parallelism between the machining surface and the datum plane; This is not the case when milling with an end milling cutter, but the perpendicularity error between the spindle axis of the milling machine and the feed direction will affect the perpendicularity and parallelism between the machining surface and the reference surface. For example, when end milling on the vertical milling machine, if the "zero position" of the vertical milling head is not allowed to use cross feed, a plane inclined to the workbench will be milled; If the longitudinal feed is used for asymmetric milling, an asymmetric concave surface will be milled. Similarly, when end milling on a horizontal milling machine, if the "zero position" of the workbench is not accurate, a slope will be milled with vertical feed; If the longitudinal feed is used for asymmetric milling, an asymmetric concave surface will also be milled. 2. Clamp the end milling vertical surface on the workbench of the horizontal milling machine It is more accurate and simple to mill the vertical surface with large size on the horizontal milling machine with an end milling cutter. In this way, the milling plane is perpendicular to the worktable. When vertical feeding is adopted, the accuracy is higher because it is not affected by the accuracy of the "zero position" of the workbench. 2、 Parallel face milling 1. End milling parallel surfaces on vertical milling machines When the workpiece has a step, the workpiece can be directly clamped on the workbench table of the vertical milling machine with a pressing plate, so that the datum plane fits the workbench table. 2. End milling parallel surfaces on horizontal milling machines When there is no step on the workpiece, the parallel surface can be milled with an end mill on a horizontal milling machine. During clamping, the positioning key can be used for positioning, so that the reference plane is parallel to the longitudinal feed direction. If the bottom surface of the workpiece is perpendicular to the reference plane, no correction is required; If the bottom surface is not perpendicular to the reference plane, it needs to be padded or re milled (so that it is perpendicular to the reference plane). When the leveling method is adopted, a 90 degree angle ruler or dial indicator is needed to correct the datum plane.

In the process of parts processing, the processing scheme will vary according to the requirements of parts or production conditions. Manufacturing the same parts in time will also lead to different process schemes of parts due to problems in production efficiency, economic benefits and so on. Therefore, when machining mechanical parts, the formulation of machining process flow of mechanical parts is very important. 1、 Production process The production process is the process of turning drawings into products. This process is also the manufacturing process of parts. In production, the process of transforming raw materials or semi-finished products into products is called production process. This process includes the following: 1. Technical preparation process: many aspects need to be prepared before machining mechanical parts, including market research, prediction, identification of new products, process design, standardization review, etc. 2. Technological process: This is a process that directly changes the shape, size or surface position of raw materials or semi-finished products. This process can make materials and semi-finished products into products. For example, the common liquid forming, plastic deformation forming, powder forming, cutting, welding, heat treatment, surface treatment, assembly and so on are all technological processes. 3. Auxiliary production process: this process is the auxiliary production activities required to ensure the normal production of mechanical parts. For example: process equipment manufacturing, energy supply and equipment maintenance, etc. 4. Production service process: although it is not directly related to production, it is a necessary process to support the production of parts, such as the organization, transportation, storage, supply of raw materials, product packaging and sales, etc. The technological process is the main body of the production process. It can be completed in a factory, or it can be dispersed to different manufacturers through the principle of professional cooperation. For example, this method is used in the manufacturing of large mechanical equipment such as automobiles, instruments and aircraft, which are common in our life. 2、 Composition of process The cutting process of parts is composed of many processes, among which the process is composed of station, work step, tool walking and installation. 1. Process: it refers to the part of the technological process that is continuously completed by a machine tool or a group of workpieces at the same working place. 2. Work step: in a process, the part where the machining surface of the workpiece, cutting tools and cutting parameters do not change in speed and feed rate is called work step. 3. Tool feeding: a layer of allowance cut by the tool on the machined surface is called one-time tool feeding. If it cannot be completed at one time, it can be cut together in several times. 4. Installation: the process that the workpiece is clamped (positioned and clamped) once is called installation. The multi-layer clamping includes two contents: positioning and clamping. 5. Station: relative to the fixed part of the tool or equipment, each processing position occupied by the workpiece is called station. Generally, the workpiece in a process is installed only once, and sometimes many times.

An inclined plane is a plane on a part that is inclined at any angle to the datum plane. The degree of inclination of the inclined plane relative to the reference plane is mainly measured by the inclination. In the processing and production of parts, milling is one of the main methods to process the inclined surface of parts. There are three methods of milling inclined plane on milling machine: workpiece inclined milling inclined plane, milling cutter inclined milling inclined plane and milling inclined plane with angle milling cutter. The need of inclined plane has certain requirements for the relationship between workpiece, machine tool and tool. Generally, the following two conditions need to be met: first, the slope of the workpiece should be parallel to the feeding direction of the milling machine workbench; Second, the slope of the workpiece should coincide with the cutting position of the milling cutter, that is, when milling with a circular edge milling cutter, the slope is tangent to the outer cylindrical surface of the milling cutter; When milling with an end edge milling cutter, the inclined plane coincides with the end face of the milling cutter. 1、 Tilt the workpiece to the required angle and install the milling slope When milling an inclined plane on a horizontal milling machine or a vertical milling machine whose end milling head cannot rotate at an angle, the workpiece can be installed at the required angle to mill the inclined plane. The following methods are commonly used: 1. Milling the inclined plane of the workpiece according to the scoring: during single piece production, first draw the processing line of the inclined plane on the workpiece, then use flat tongs to clamp the workpiece, use the scoring disc to correct that the processing line drawn on the workpiece is parallel to the feeding direction of the workbench, and mill the inclined plane with a cylindrical milling cutter or end milling cutter. 2. Turn the angle of the jaw body of the flat tongs to clamp the workpiece milling inclined plane: install the flat tongs, first correct that the fixed jaw is vertical or parallel to the spindle axis of the milling machine, and then turn the jaw body to the required angle through the scribed line on the base of the flat tongs, clamp the workpiece, and mill the required inclined plane. 3. Use the inclined sizing block to clamp the workpiece and mill the inclined plane: use the inclined sizing block to tilt the workpiece datum plane, use the flat tongs to clamp the workpiece and mill the inclined plane. The inclination of the sizing block used shall be the same as that of the inclined plane, and the width of the sizing block shall be less than the width of the workpiece. This method is convenient for milling inclined planes, clamping and correcting workpieces, easy to manufacture inclined sizing blocks, and when milling a batch of workpieces, the milling depth does not need to be readjusted with the replacement of workpieces, so it is suitable for small batch production. In mass production, special fixtures are often used to clamp the workpiece and mill the inclined plane. 2、 Tilt the milling cutter to the required angle and then mill the inclined plane On the vertical milling machine with the rotation angle of the spindle of the end milling head, install the end milling cutter or end milling cutter, and clamp the workpiece with flat tongs or pressing plates to mill the required inclined plane. When clamping workpieces with flat tongs, there are two common methods: 1. The reference plane of the workpiece is parallel to the worktable to clamp the workpiece. 2. The reference plane of the workpiece is perpendicular to the worktable top to clamp the workpiece. 3、 Milling inclined plane with angle milling cutter The inclined plane with narrow width can be milled with angle milling cutter. The angle of the angle milling cutter shall be selected according to the angle of the workpiece slope, and the width of the milled slope shall be less than the blade width of the angle milling cutter. When milling symmetrical double inclined planes, two angle milling cutters with the same diameter and angle and opposite cutting edges should be selected for milling at the same time. When installing the milling cutters, the cutting edges and teeth of the two milling cutters should be staggered to reduce milling force and vibration. Because the strength of the cutter teeth of the angle milling cutter is weak, the arrangement of the cutter teeth is dense, and it is difficult to remove chips during milling, so when using the angle milling cutter for milling, the selected milling amount should be about 20% lower than that of the cylindrical milling cutter, especially the feed per tooth should be appropriately reduced. When milling carbon steel and other workpieces, sufficient cutting fluid should be applied.

In the early design process of industrial products, forming materials will be selected. Because the tone of materials is closely related to the production, assembly and completion time of products. In addition to these, the verification level of quality, market sales and price determination also need to be considered. So, what are the commonly used injection molding materials? 1. As styrene acrylonitrile copolymer It is generally used in the packaging and manufacturing of electrical, household goods, automotive industry, household goods, cosmetics, etc. Process conditions of injection molding: dry treatment. If the storage is not appropriate, as will have hygroscopic properties. Melting temperature, between 200 and 270 degrees. For processed thick wall products, the melting temperature lower than the lower limit can be used. The mold temperature is between 40 and 80 degrees, while for reinforced materials, the mold temperature generally will not exceed 60 degrees. Attention should be paid to the design of the cooling system, because this time it directly affects the appearance, shrinkage and bending of the products. Injection pressure: 350-1300bar, high-speed injection is recommended. 2. Polystyrene Polystyrene is a kind of thermoplastic, which is transparent when it is not colored. The sound of knocking products will have the crisp sound of metal, with good gloss and transparency, but it is brittle and easy to produce cracks. Process conditions of injection molding: drying treatment: unless stored improperly, drying treatment is usually not required. Melting temperature: between 180 and 280 degrees. For flame retardant materials, the upper limit is 250 degrees. Mold temperature, between 40 and 50 degrees. Injection pressure: 200-600bar, rapid injection is recommended. 3. ABS resin ABS material is an engineering plastic, which is mainly composed of copolymers of acrylonitrile (a), butadiene (b) and styrene (s). 4. Carbonate Referred to as PC engineering plastics, PC material is a kind of engineering plastics. PC is an amorphous thermoplastic resin with excellent comprehensive performance, which has excellent electrical insulation, extensibility, dimensional stability, chemical corrosion resistance, high strength, heat resistance and cold resistance; At the same time, its advantages include self extinguishing, flame retardant, non-toxic, colorable, etc., which are very commonly used in engineering production. At the same time, PC plastic is widely used in life, and its cost is low due to its large-scale industrial production and easy processing characteristics. Because of its good strength and toughness, its strength can meet various needs from mobile phones to bulletproof glass. However, its disadvantage is that it is not hard enough compared with metal, which leads to its appearance being easy to scratch. The above are injection molding materials that are common in industrial production. These are only commonly used in production. There are many injection molding materials that are not commonly used but have their own characteristics. In the process of production, materials need to be selected according to production needs. The price of injection molding materials will also vary according to different types, models, market environment and so on.

Spline connection is a connection form that can transmit large torque and high centering accuracy. It is widely used in mechanical transmission. In the gearbox of machine tools, automobiles, tractors and so on, the sliding of spline gear sleeve and spline shaft is mostly used as variable speed transmission. Therefore, we must pay attention to its accuracy and quality when manufacturing external splines. Now let's introduce the quality inspection and analysis of external spline. 1、 Inspection of external spline In single piece and small batch production, the deviation of various elements of external spline is generally detected with general measuring tools (vernier caliper, micrometer, dial indicator, etc.). The measurement items are as follows: (1) Measure the key width and small diameter of the external spline with a micrometer or vernier caliper. (2) Use a dial indicator to measure the parallelism and symmetry of the side of the external spline key to the axis of the workpiece. The measurement method of symmetry is compared with the measurement method of trial cutting and knife alignment. In batch and mass production, the inspection method of combining comprehensive gauge and single stop gauge is adopted. The comprehensive gauge of external spline shall be used to check the comprehensive influence of small diameter, large diameter, key width and large diameter on the coaxiality of small diameter, the symmetry and bisection of spline, etc., so as to ensure the matching requirements and installation requirements of spline. The comprehensive ring gauge has only the through end, so it is also necessary to check the minimum limit dimensions of small diameter, large diameter and key width with a single end stop gauge (chuck) to ensure that its actual dimension is not less than the minimum limit dimension. During the inspection, if the comprehensive gauge passes and the single end clamp fails, the external spline is qualified. 2、 Quality analysis of external spline milling 1. Precautions for external spline milling When milling external splines with a three face edge milling cutter on the milling machine, the following matters should be paid attention to: (1) Accurately correct the position of the fixture (dividing head, tailstock), and ensure that the workpiece axis is parallel to the workbench table and consistent with the longitudinal feed direction. (2) Under the condition that the width of the three side edge milling cutter does not cut to the side of the adjacent key, a large size should be selected to increase the rigidity of the milling cutter. The cutting edge of the milling cutter should be sharp, and the runout of the side cutting edge should be small after installation. (3) Carefully adjust the cutting position of the milling cutter. When milling with a single cutter, the tool setting must be accurate. (4) Carefully operate the indexing operation to prevent the error of indexing or the inaccuracy of bisection caused by the failure to eliminate the indexing gap. (5) Select the milling amount reasonably to avoid the ripple on the side of the key caused by vibration during machining. For the slender spline shaft with poor rigidity, measures should be taken to improve the rigidity in workpiece processing. 2. Quality analysis of external spline milling Common quality problems, causes and corresponding measures in external spline milling: (1) Key width size out of tolerance: the main reason is that the cutting position is not adjusted correctly or the tool end edge runout is too large when milling with a single tool. It can be improved by accurately adjusting the cutting position of the milling cutter, replacing the washer and reinstalling the milling cutter. (2) Out of tolerance of spline symmetry: caused by inaccurate calculation, adjustment or indexing of cutting position. It can be improved by re setting the tool or dividing it correctly. (3) The spline is not evenly divided: the main reasons are that the workpiece center is different from the dividing head, the shaft of the dividing head is too large, and the dividing head is shaken incorrectly. The solution can be used to accurately correct the coaxiality of the workpiece axis and the dividing head; The rotation direction of the indexing handle is consistent to eliminate the gap; Correct indexing method. (4) The spline is not parallel to the reference axis: the reason for this situation is that the spindle axis of the dividing head is not parallel to the longitudinal feed direction, and the tailstock center is different from the axis of the dividing head, which can be improved by re calibrating the fixture.

The consequences of machine collision accident in CNC machining are very serious. Once the tool or tool holder collides with the workpiece or machine tool, the light one will cause damage to the tool and scrap the machined parts, and the heavy one will damage the parts of the machine tool, resulting in inaccurate accuracy and even failure to work normally. What's more, the collision may cause personal injury accidents. Therefore, in the process of NC machining, machine collision is absolutely a kind of machining accident to avoid. This requires the operator to develop a careful working habit, operate the machine tool in the correct way, and reduce the occurrence of tool collision. There are many different reasons that may cause a crash. Let's make a summary below. Only by understanding the reasons that may cause a crash, can we carry out targeted prevention. The reasons for the collision mainly include the following nine points: Programming error First of all, there are errors in the preparation of the processing program, specifically including errors in process arrangement, inadequate consideration of the process undertaking relationship, and errors in the setting of processing parameters. For example, the top of the actual workpiece is coordinate 0 point, but its bottom is set as coordinate 0 point in machining; The set safety height is not enough, so that the tool does not completely leave the workpiece when it is lifted; The allowance setting of secondary roughening is less than that of the previous knife, which may cause a collision accident. Therefore, after the program is written, the path of the program must be analyzed and checked. Only when there is no problem can it be started and run. Program sheet remarks error If there are no comments, incorrect comments or incomplete comments on some similarities that need to be noted in the procedure, it may cause a collision. For example, the one-sided collision number is written as the four sided median; Mark the clamping distance of the vise or the protruding distance of the workpiece incorrectly; Unclear or incorrect remarks on the extension length of the tool will lead to machine collision. In order to avoid the occurrence of the above situations, the program sheet should be noted in detail as much as possible, and the principle of replacing the old with the new should be adopted during the design change, and the old program sheet should be destroyed and no longer used. Tool measurement error If the size measurement of the tool is wrong, for example, the length of the tool bar is not taken into account when inputting the tool data; Too short tool loading and relatively long extension of the tool will also cause the tool to collide with other equipment or workpieces. Therefore, accurate instruments should be used to measure the tool, and scientific methods should be adopted. The length of the tool should be 2 to 5 mm longer than the actual depth. Program transfer error If the program number call is wrong or the program is modified, but the modified program is not called, but the old program is still used for processing, it will cause a collision due to the program transmission error. In order to avoid these situations, the detailed data of the program must be checked before processing, including the time and date of program writing, and the simulation must be carried out first. The simulation can be officially run only when there is no accident. Knife selection error Improper tool size selection or inconsistent with the tool with parameters set in the program will also cause machine collision. Blank exceeds expectation The blank size exceeds the size set by the program, which hinders the operation of equipment and tools, and it is easy to cause machine collision accidents. Problem of workpiece material itself For example, the workpiece itself has defects, or the hardness of the workpiece is too high, which is also a major reason for the collision. Clamping factors Cushion blocks are often used in clamping, because the use of cushion blocks will lead to changes in the actual position and size of the workpiece. If the influence of the cushion block is not taken into account when programming, there may be a machine collision phenomenon. Machine failure Sudden power failure, lightning and other accidents will also cause a crash. With the continuous humanization of machine tool functions, anti-collision machine detection technology began to appear and put into use, which played a certain guarantee for preventing collision.

There are many factors that affect the machining accuracy of parts, among which the accuracy of machine tool is one of the main factors. After long-term use or major repair of the machine tool, all important accuracy indicators should be checked and tested. Geometric accuracy is one of the accuracy of machine tools, which refers to the mutual position accuracy of various components and the shape and position accuracy of main parts when the machine tool is running. The geometric accuracy test of machine tools is a static test under non working conditions. Geometric accuracy test of common milling machines 1. Precision inspection of milling machine workbench (1) Inspection of flatness of worktable. Make the workbench in the middle of the longitudinal and transverse travel, place two gauge blocks with equal height on the workbench table in all directions, put a test ruler on the two gauge blocks, and then use a feeler gauge and gauge block to test the distance between the workbench table and the ruler. (2) Verticality inspection of the longitudinal and transverse movement of the workbench. Place the 90 degree ruler in the middle of the workbench, make one inspection surface of the 90 degree ruler parallel to the horizontal (or longitudinal) direction, move the workbench longitudinally (or horizontally), and use a dial indicator to inspect on the other inspection surface of the 90 degree ruler. The maximum difference between the readings of the dial indicator is the perpendicularity error. During inspection, the lifting table should be locked. (3) The parallelism inspection of the worktable top by the longitudinal movement of the worktable. Make the worktable in the middle of the horizontal stroke. On the worktable top, cross the center, place two gauge blocks with equal height in the T-shaped groove, place the inspection ruler on it, push the dial indicator contact on the inspection surface of the ruler, and move the worktable longitudinally for inspection. The maximum difference between the readings of the dial indicator is the parallelism error. During inspection, the traverse feed and lifting table should be locked. (4) The parallelism of the worktable top is tested by the horizontal movement of the worktable. Place two gauge blocks with the same height in the middle of the worktable and parallel to the horizontal moving direction of the worktable, place the inspection ruler on it, place the dial indicator contact in the center of the spindle, and make it top on the inspection surface of the ruler, and move the worktable horizontally for inspection. The maximum difference between the readings of the dial indicator is the parallelism error. During inspection, the lifting table should be locked. (5) The parallelism test of the T-shaped groove in the center of the workbench facing the longitudinal movement of the workbench. Make the workbench in the middle of the horizontal stroke, push the dial indicator contact against the inspection surface of the special slider close to the side of the central T-shaped groove, and move the workbench longitudinally for inspection. The maximum difference between the readings of the dial indicator is the parallelism error. Both sides of the central T-groove shall be inspected. During inspection, the traverse feed and lifting table should be locked. 2. Precision inspection of milling machine spindle (1) Axial runout inspection of spindle. Push the dial indicator contact against the center of the end face of the special inspection rod inserted into the taper hole of the spindle, and rotate the spindle for inspection. The maximum difference between the readings of the dial indicator is the error of axial jump. The axial runout tolerance of the spindle of common milling machines is 0.01mm. The axial jump error is too large, which will produce large vibration and inaccurate size control during processing, as well as the phenomenon of tool dragging. The axial jump error is too large. If it is caused by too tight or loose adjustment of the bearing, the specified requirements can be achieved by adjusting the tightness of the bearing; If it is caused by the wear of the main shaft, the main shaft needs to be replaced. (2) Runout inspection of bearing surface of spindle shoulder. The end face circular runout tolerance of the bearing surface of the spindle shoulder of common milling machines is 0.02mm. If the end face circular runout error of the bearing surface of the shaft shoulder is too large, it will cause the end face circular runout of the milling cutter positioned and installed with the shaft shoulder of the spindle, affect the dimensional accuracy and surface roughness of the parts, accelerate the wear of the milling cutter due to uneven wear of the cutter teeth, and reduce the service life of the milling cutter. The solution to the excessive runout error of the bearing surface of the shaft shoulder is the same as the solution to the excessive axial runout error of the main shaft. (3) Horizontal milling machine spindle rotation axis to the table surface parallelism inspection. The parallelism tolerance of the spindle rotation axis of common milling machines to the worktable surface is 0.03mm, and the protruding end of the inspection rod is only allowed to tilt downward. If the parallelism error is too large, it will affect the parallelism of the machined surface of the part. If the transverse secondary feed is made, obvious tool joint marks will be produced. If the parallelism error exceeds the tolerance, adjust the bearing to meet the specified requirements.

Cutting grooves is an important processing method. To successfully complete this processing, you must master the following ten key points: Understand groove types There are three main types of grooves: cylindrical groove, inner hole groove and end face groove. The cylindrical groove is convenient for chip removal and processing quality inspection, and it is relatively easy to process. When the tool tip of the grooving tool is kept slightly below the center line, the cutting effect is the best. Inner hole grooving is more challenging in the application of coolant and chip removal. The best performance can be obtained when the tool tip is slightly higher than the centerline. When machining the end groove, the tool must be able to move along the axial direction, and the radius of the back face of the tool must match the radius to be machined. The machining effect is the best when the tool tip position is slightly higher than the centerline. Machine tools and Applications Turning and grooving requires the machine tool to have enough power, rigidity, accuracy and coolant pressure and flow. In addition, in order to process the correct groove shape and size, it is also crucial to properly debug and calibrate the machine tool. Understand the material characteristics of the workpiece It is necessary to understand the tensile strength, work hardening characteristics and toughness of the workpiece material. For different workpiece materials, different cutting speeds, feed rates and tool characteristics should be adopted, including the specific geometry and coating of the tool, which is necessary for chip removal and prolonging the service life of the tool. Select the correct tool Turning and grooving can be completed by cutting in at one time or by cutting in multiple times and step by step. The tools selected by the two methods are different. Choosing the right cutting tools according to the processing needs and processing methods determines the cost-effectiveness of processing. Forming tool The forming tool can cut in all or most of the groove shapes at one time, so it can vacate the tool position and shorten the processing cycle time, which is suitable for mass processing. In addition, when selecting, we should also consider the chip generated by the control tool and the machine power required for forming cutting. Select single point multifunctional tool The use of multi-functional tools can generate tool paths in the axial and radial directions, so it can not only process grooves, but also turn out diameters, interpolate radii, and process angles. In addition, the multi-function tool can also carry out multi-directional turning. In this way, the time of tool change or empty stroke movement can be reduced and the machining efficiency can be improved. Adopt correct processing sequence The correct processing sequence needs to consider many factors. For example, after the groove is processed first, the strength of the workpiece will be reduced, affecting the parameter setting of the next process; After the internal and external diameter turning is completed, the machining shall be started from the farthest point from the tool chuck to avoid the burr being pushed into the machined groove in the next process. Effect of feed rate and cutting speed The wrong setting of feed rate and cutting speed will cause chatter and reduce the service life and machining efficiency of the tool. When setting the feed rate and cutting speed, the effects of workpiece material, tool geometry, type and concentration of coolant, blade coating and machine tool performance should be fully considered. For various cutting tools, the manufacturer will generally provide the latest and most practical processing parameter information as a reference. Select blade coating The coating can play a lubricating role between the tool and the chip, so it can improve the service life of the cemented carbide blade, improve the machining efficiency and improve the surface finish of the workpiece. At present, commonly used coatings include TiAlN, tin, TiCN, etc. in order to obtain the best performance, the coating must match with the processed material. Cutting fluid Cutting fluid has the dual functions of cooling and chip removal, so it is necessary to provide sufficient cutting fluid at the cutting point of the grooving blade and the workpiece. When machining the inner diameter groove of blind hole, increasing the cutting fluid pressure at the cutting point is very effective for improving chip removal. High pressure cooling has obvious advantages for grooving of difficult to machine materials. Generally speaking, the typical concentration of water-soluble coolant is between 3% and 5%. Sometimes, in order to improve the lubricity, the concentration can also be increased to no more than 30%.