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How to Milling Noncircular Gears in Precision Parts Processing

How to Milling Noncircular Gears in Precision Parts Processing When the polar axis of pitch curve of non-circular gear is not a tooth groove but a tooth peak during precision parts processing, the included angle between the polar axis and the radial diameter of point A of the initial processing tooth groove shall be considered during adjustment calculation, which is equal to the angle corresponding to the arc length from the polar axis to the half pitch (π m/2) of the adjacent tooth groove. When selecting the number of milling cutter, the close circle radius (radius of curvature) of the midpoint of the arc length of the tooth groove to be cut on the pitch curve shall be obtained first, and then the number of teeth of the equivalent cylindrical gear of each tooth groove shall be calculated according to the module m of the gear to select the cutter number of the modular milling cutter. If the accuracy requirement is not high, the number of milling cutter can be selected according to the equivalent gear teeth with the largest curvature radius. In order to facilitate tool setting during precision parts processing, the machining shall be started from the 0 end of the long sleeve with grooves. After alignment, the machining can be carried out without rotation. After milling the tooth groove on the first section of arc by angle A1 around the rotation center O1, turn the angle A2, and then move the rotation center to the second section of arc center O2. Turn the angle A3 to mill the first gear groove 3 on the second arc, and then mill all the gear grooves on the second arc according to the angle A4. Milling out all the grooves in the same operation sequence as above.

2022

12/27

Classification standards and types of CNC machine tools

There are many types of CNC machine tools, which can be classified from different angles, different classification standards corresponding to different classifications, today by me to introduce you to two of the classification methods, that is, according to the movement and control mode for classification, the specific content of the following. CNC machine tools can be divided into, according to the movement mode   (1) point position control system   Only control the position of the tool to move from one point to another, and in the process of moving without cutting process, such as coordinate boring machine, drilling machine and punching machine. The coordinate position is required to have high positioning accuracy, in order to improve productivity, the highest feed speed set by the machine tool is used for positioning movement, before approaching the positioning point to be graded or continuous speed reduction in order to converge to the end point at low speed, thus reducing the inertial overshoot of the moving parts and the positioning error caused by this. No cutting process is performed during the positioning movement, so there is no requirement for the motion trajectory.   (2) Linear control system   Linear control system is to control the precise movement of the tool or base table from one position to another at a certain speed, along a direction parallel to a coordinate axis. It is also called point position linear movement control system.   (3)Contour control system   Is the control of two or more coordinate axes at the same time (two-axis, two-and-a-half-axis, three-axis, four-axis, five-axis linkage), it is not only to control the starting and ending coordinates of the moving parts of the machine tool, but also to control the speed, direction and displacement of each point of the entire machining process, that is, to control the trajectory of processing, processing the required contour. Motion trajectory is any slope of the straight line, arc, spiral line, etc.. This type of machine tool CNC device is the most complete, able to carry out two coordinates or even multi-coordinate linkage control, but also able to point and linear control. CNC machine tools according to the movement, can be divided into.   (1) open-loop CNC machine tools   Refers to the control system without feedback, no position feedback elements within the system, usually using stepper motors as the actuator. The input data through the numerical control system of computing, issued a command pulse, through the ring distributor and drive circuit, so that the stepper motor turned a step angle, and then through the transmission mechanism to drive the table to move a pulse equivalent distance. The moving speed and displacement of the moving parts are determined by the frequency and number of pulses of the input pulse.   (2) Semi-closed-loop CNC machine tools   Install angular displacement detection device (photoelectric encoder or induction synchronizer) at the end of the drive motor or at the end of the drive screw to indirectly measure the actual position or displacement of the actuating part by detecting the angle of the motor or screw, and then feedback to the CNC system. Obtain higher accuracy than the open-loop system, but its displacement accuracy is lower than that of the closed-loop system, and it is easy to achieve system stability compared with the closed-loop system. Now most CNC machine tools are widely used this semi-closed-loop feed servo system, inertia of the machine tool moving parts are not included in the detection range.

2022

12/26

CNC machining three influencing factors

CNC machining surface geometric characteristics include several aspects of surface roughness, surface waviness, and surface machining texture. Surface roughness is the basic unit constituting the geometric characteristics of the machined surface. When processing the surface of the workpiece with metal cutting tools, the surface roughness is mainly affected by the role and influence of geometric factors, physical factors and CNC machining process factors in three aspects. What are the specific effects of it, the following by me to introduce you to. (1) Geometric factors   From the geometric point of view, the shape and geometric angle of the tool, especially the radius of the tip arc, the main deviation angle, the sub-deviation angle and the amount of feed in the cutting dosage, etc. have a greater impact on the surface roughness.   (2) Physical factors   Considering the physical substance of the cutting process, the cutting edge rounding of the tool and the back extrusion and friction make the metal material plastic deformation, which seriously deteriorates the surface roughness. In the CNC lathe processing plastic materials and the formation of ribbon chips, the chip accumulation tumor with high hardness is easily formed on the front tool face. It can replace the front tool face and cutting edge for cutting, so that the geometric angle of the tool and the back eat tool amount are changed. The profile of the chipformer is very irregular, thus causing the surface of the workpiece to have tool marks of varying depth and width. Some of them are embedded in the workpiece surface, which increases the surface roughness. The vibration during the cutting process increases the value of the surface roughness parameter of the workpiece. (3) Process factors   From the perspective of the process to consider its impact on the surface roughness of hardware parts processing, mainly with cutting tools related factors, factors related to the workpiece material and factors related to CNC machining conditions.

2022

12/26

Panel CNC machining: Maintenance of precision gauges and maintenance tips

1, when measuring parts on the machine tool, to wait for the parts to stop completely, or not only make the measuring surface of the gauge premature wear and loss of precision, and will form an accident. Especially when the turner use external card, do not think the caliper is simple, wear a little does not matter, pay attention to the castings often have pores and shrinkage, once the foot falls into the pore, the operator's hand can be pulled in, forming a serious accident. 2, measurement should be measured before the measuring surface of the gauge and parts of the measured surface to wipe clean, to avoid the presence of dirt and affect the accuracy of measurement. With fine gauges such as vernier calipers, percentages and percent tables, etc., to measure the forging blank, or with abrasive (such as emery, etc.) of the appearance is wrong, so easy to make the measurement surface soon wear and lose accuracy.   3, the gauge in the use of the process, do not and things, tools such as files, hammers, turning tools and drill number stacked together, so as not to bruise the gauge. Do not just put on the machine tool to avoid the machine tool oscillation and make the gauge fall down damage. Especially vernier calipers, etc., should be placed flat in a special box, so as not to deform the body of the ruler. 4, the gauge is the measurement of things, certainly not as a substitute for other things. For example, take the vernier caliper scribe line, take the percentage ruler as a small hammer, take the steel ruler as a screw screw driver, as well as the steel ruler to clean up chips, etc. are wrong. The gauge as a toy, such as the percentage rule in the hands of arbitrary waving or shaking, etc. is also wrong, are easy to make the gauge lose accuracy.   5, the temperature has a great impact on the measurement results, the fine measurement of parts must make parts and gauges are measured at 20 ℃. Usually can be measured at room temperature, but it is necessary to make the workpiece and the gauge temperature consistent, otherwise, due to the characteristics of the thermal expansion and contraction of metal materials, so that the measurement results are not accurate. Temperature also has a great impact on the accuracy of the gauge, the gauge should not be placed in the sun or on the bedside box, because the temperature of the gauge increases, but also can not measure the exact scale. Do not put the fine gauge in the vicinity of heat sources (such as electric furnaces, heat exchangers, etc.) to avoid heat deformation of the gauge and loss of precision.

2022

12/26

Tips for CNC machining

CNC processing is also called computer gongs, CNCCH or CNC machine tools is actually a call over in Hong Kong, later introduced to the mainland Pearl River Delta, in fact, is the CNC milling machine, in Guang, Jiangsu, Zhejiang and Shanghai, someone called "CNC machining center" it is used in an extremely wide range, compared to other processing technology has more advantages. Important we mastered the following skills, in the processing can be more smooth. 1. White steel knife speed should not be too fast.    2. the copper worker open rough less use white steel knife, more use of flying knife or alloy knife   3. when the workpiece is too high, it should be layered with different lengths of knives for roughing.   4. with a large knife to open the rough, the application of small knives and then remove the remaining material, to ensure that the balance is consistent before the light knife.   5. flat application flat bottom knife processing, less ball knife processing, in order to reduce processing time. 6. brass work to clear the corner, first check the corner on the R size, and then determine how much to use the ball knife.   7. calibration table plane four corners to gong flat.   8. Where the slope is an integer, apply the slope knife processing, such as the pipe position.   9. before doing each process, think clearly about the amount of spare capacity left after the previous process, in order to avoid empty knives or processing too much and knives.   10. try to take the simple knife path, such as shape, grooving, single-sided, less go around the same height. 11. take WCUT, can take FINISH, do not take ROUGH.   12. when the shape of the light knife, first rough light, then fine light, the workpiece is too high, first light edge, then light bottom.   13. Set the tolerance reasonably to balance the machining accuracy and computer calculation time. When roughing, set the tolerance to 1/5 of the margin, and when varnishing, set the tolerance to 0.01.   14. Do more processes to reduce empty tool time. Do a little more thinking to reduce the chance of making mistakes. Make more auxiliary lines and surfaces to improve the machining condition. 15.   15. Establish a sense of responsibility and check each parameter carefully to avoid rework.   16. Be diligent in learning, good at thinking, and keep improving. Milling non-planar, use more ball cutters, less end cutters, don't be afraid to join the cutters; small cutters to clear the corners, large cutters to refine; don't be afraid to make up the surface, proper making up the surface can improve the processing speed and beautify the processing effect.

2022

12/26

What is required for precision machining

1, in terms of hardware, mechanical parts processing is a variety of mechanical equipment, such as lathes, milling machines, planers, grinding machines, broaching machining centers, etc., the inherent processing accuracy of various devices are different, so to achieve precision machining, it depends on how high the accuracy of your parts corresponding selection of the corresponding process routes and equipment;   2, from the software, that is, the skills of the operator, which involves a variety of equipment operators operating skills, these skills include in-depth understanding of the equipment, understanding of machining, understanding of the material of the processed parts, etc., these skills can then slowly accumulate in the usual work, the key to the skills of the operator is practice, theory should also understand. Machining is the process of changing the size or performance of a workpiece through a mechanical device. According to the difference in processing can be divided into cutting processing and.   The production process of a machine is the entire process of making a product from raw materials (or semi-finished products). For the production of machines including the transport and preservation of raw materials, production preparation, the manufacture of blanks, parts processing and heat treatment, product assembly, and commissioning, painting and packaging. The content of the production process is very broad, modern enterprises use the principles and methods and guide production, the production process is seen as a production system with input and output.

2022

12/26

Precision parts processing of hardware process

Hardware processing can be divided into: automatic lathe processing, CNC processing, CNC lathe processing, five-axis lathe processing, according to the general can be divided into: hardware surface processing, hardware molding processing two categories. What is the surface processing? A, hardware surface processing subdivision can be divided into: hardware painting processing, electroplating, surface polishing processing, hardware corrosion processing and so on.   1、Painting processing: At present, hardware factories in the production of large pieces of finished hardware are used to paint processing, through the paint processing to avoid rusting hardware, such as: daily necessities, electrical shells, crafts, etc..   2, electroplating: electroplating is also the most common hardware processing a processing technology, through modern technology to the surface of the hardware electroplating, to ensure that the product does not occur under the long use of mold embroidery, electroplating processing common: screws, stamping parts, battery pieces, car parts, small jewelry, etc..   3、Surface polishing processing: surface polishing processing is generally used in daily necessities for a long time, through the surface burr processing of hardware products, the sharp edges and corners of the part thrown into a smooth face, so that in the process of use will not cause harm to the human body. Second, hardware molding process mainly includes: die-casting (die-casting is also divided into cold pressing and hot pressing), stamping, sanding, solution casting and other processes.

2022

12/26

Influence of temperature on the process in the machining of precision parts

In the actual machining production process in a variety of heat sources (friction heat, cutting heat, ambient temperature, thermal radiation, etc.), machine tools, tools, workpieces being machined and other temperature changes will produce thermal deformation, which affects the relative displacement between the workpiece and the tool, resulting in processing errors, and then affect the machining accuracy of the parts. Such as the coefficient of linear expansion of steel 0.000012 / ℃, for the length of 100mm steel, when the temperature rises 1 ℃ will elongate 1.2 μm. temperature changes in addition to directly affect the expansion of the workpiece, the accuracy of machine tools and equipment also has an impact. In the precision machining, the workpiece processing accuracy and precision of the stability of higher requirements. According to relevant statistics, in precision machining, the processing error caused by thermal deformation accounts for 40%-70% of the total processing error. Therefore, in the high-precision precision machining, in order to avoid the expansion and contraction of the workpiece due to temperature changes, the reference temperature of the environment is generally strictly defined. And the deviation range of temperature change is set, 20℃±0.1℃ and 20±0.01℃ of constant temperature processing has appeared. In general, for precision processing with constant temperature and humidity laboratory, in order to avoid the processed workpiece in the processing and measurement of temperature changes due to expansion and contraction, generally strict provisions of the benchmark temperature of the room, and the development of temperature changes in the range of deviation, while the requirements for the relative humidity of the air is not as strict as the precision requirements of textile testing. Such as a national ultra-precision processing laboratory, the required temperature is 20 ℃ ± 0.2 ℃, while the relative humidity is 45% ± 5%.

2022

12/26

Let you understand the machining process route of precision mechanical parts

1、Determine the processing method of each surface. On the basis of understanding the characteristics of various processing methods and mastering their processing economic accuracy and surface roughness, choose the processing method to ensure processing quality, productivity and economy.   2、Choose the positioning reference. According to the principle of rough and fine datum selection, reasonably select the positioning datum of each process. 3, the development of the process route. On the basis of the analysis of the part, divide the part rough, semi-finish, finishing stages, and determine the degree of concentration and dispersion of the process, reasonable arrangement of the processing order of the surface, so as to develop the machining process route of the part. For the more complex parts, you can first consider several options, analysis and comparison, and then choose a more reasonable processing program.   4, determine the machining allowance of each process and process dimensions and their tolerances.   5, the choice of machine tools and tools, clamps, measurement, cutting tools. The choice of machinery and equipment should not only ensure the quality of processing, but also to economic and reasonable. In batch production conditions, generally should use general-purpose machine tools and special fixtures. 6, to determine the technical requirements of the main processes and inspection methods.   7, to determine the cutting amount and time quota for each process. Single piece of small batch production plant, cutting amount more by the operator's own decision, machining process cards are generally not clearly specified. In the batch, especially in the mass production plant, in order to ensure the rationality of production and the rhythm of the balance, it is required to specify the cutting amount, and not arbitrarily altered.   8, fill in the process documentation.

2022

12/26

Requirements and standards for precision parts processing

For precision parts processing is mainly dimensional requirements, such as how much the cylindrical diameter, there are strict requirements, positive and negative error within the specified requirements to be qualified parts, otherwise they are unqualified parts; length, width and height also have specific strict requirements, positive and negative error is also specified, such as an embedded cylinder (take the most simple basic parts for example), if the diameter is too large, more than the error allowed range, it will Caused by, insert not into the situation, if the actual diameter is too small, more than the lower limit of the negative value of the error allowed, it will cause inserted too loose, not solid problems occur. These are unqualified products, or the cylindrical length is too long or too short, beyond the error tolerance range, are unqualified products, are to be scrapped, or re-processed, which will inevitably cause an increase in costs. Precision parts processing requirements is in fact the main size problem, must be strictly in accordance with another plus drawings for processing, processing out of the actual size will certainly not be the same as the theoretical size of the drawings, only, as long as the processing size within the error tolerance is qualified parts, so the requirements of precision parts processing is in strict accordance with the theoretical size for processing.   Second is the advanced precision parts processing equipment and testing equipment, advanced processing equipment makes processing precision parts easier, higher precision, better results. Testing equipment can detect the parts that do not meet the requirements, so that all the products sent to customers really meet the requirements.

2022

12/26