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

We know that shaft parts are one of the most commonly used parts in machines, and also one of the very important parts, because it is about the supporting role of transmission parts and transferring torque, so how do shaft parts achieve mechanical processing? The following I will introduce to you. First of all, we need to understand the technical requirements of shaft parts and processing requirements, what are the general technical requirements of shaft parts? Let's look at the following specific.   1, diameter accuracy, geometric shape accuracy   In the shaft, the support journal and with the journal is very important, its diameter accuracy of IT5-IT9 level, and shape accuracy, should be controlled within the diameter tolerance, and its requirements are higher than the diameter accuracy.   2、Mutual position accuracy   If the shaft is common accuracy, then its radial circular runout, if it is to be matched with journal to support journal, is generally regarded as 0.01-0.03mm. while the high accuracy shaft is 0.001-0.005mm. if there are special requirements, then it should be specified clearly.   3、Surface roughness   Because the machine precision, running speed and other factors, resulting in shaft parts of the surface roughness requirements are also different. The surface roughness of the bearing journal is 0.16-0.63um, and that of the mating journal is 0.63-2.5um.   4、Materials, blanks and heat treatment of spindle   Shaft parts, the commonly used material is 45 steel, and through normalizing, annealing, tempering and quenching these treatments, so as to obtain a certain strength, hardness, wear resistance and toughness. For high speed shaft parts, alloy structural steel can be used, because it will improve wear resistance and fatigue resistance after heat treatment. Blanks for spindles are usually forgings and round steel, which can reduce the amount of cutting and machining, and can improve the mechanical properties of the material.

We are familiar with the process processing there are three: disappearing mold casting, sand casting and metal casting, which metal casting cooling speed is the fastest, cooling curve up and down does not appear eutectic platform, the number of graphite in the metallographic organization is greatly reduced, extended machine tool castings radially generated a large number of fine primary and secondary carbide, its hardness and impact toughness is significantly better than the other two casting methods. The results of vanishing mold casting and sand casting are relatively close, with only slight differences. Before the eutectic reaction, the cooling curves of both almost overlap, but the difference between the two increases from the beginning of the eutectic reaction. Compared with sand casting, the co-crystal reaction time of vanishing die casting is relatively longer, and the cooling rate after the co-crystal reaction is relatively slower, so the co-crystal matrix of vanishing die casting is coarser, the number of carbides is reduced, the number of graphite is increased, and the corresponding hardness and impact toughness are reduced. The solidification characteristics of vanishing mold casting machine tool castings.   1, disappearing mold machine tool castings cooling solidification speed is slow, slower than ordinary sand casting.   2, disappearing mold casting in the negative pressure casting, casting steel is good, casting cast iron parts will not appear up the body, castings since the shrinkage capacity, greatly reducing the appearance of the casting shrinkage tendency.   3, disappearing mold casting machine tool casting cooling rate is slow, castings by casting resistance is small, less than clay sand casting, so the formation of castings stress is small, warm tendency is small.

The material of machine tool castings is fine and high quality gray cast iron, melting with 45% steel to improve the rigidity of machine tool castings; some customers also request to do ductile iron, which is more rigid than gray cast iron, but there is a big gap in damping effect compared to gray cast iron, and the casting cost is much higher than gray cast iron; so ductile iron is not suitable for the main components of machine tools, but more suitable for machine tool table castings Use. The advantages of using gray cast iron for machine tool castings.   1, gray iron casting machine tool castings low cost, gray cast iron has good casting performance, easy to cast a variety of complex structure of the shape.   2, cast iron material has good vibration damping performance, more conducive to avoid vibration when the machine tool is running, reduce noise.   3, compared with steel cast iron, although the tensile strength is lower, but the compressive strength is close to steel, most machine tool beds do not require high tensile strength, can fully meet the performance requirements;.   4, cast iron machine bed castings made of gray iron have good lubricating properties, because the micro-pores in the atomic structure of gray iron can accommodate more lubricating oil, while the carbon elements contained have a self-lubricating effect.   5, cast iron than steel has better corrosion resistance, easy to maintain the accuracy of the machine tool guide. Machine tool bed castings have good dimensional stability, used to make machine tool beds should not be deformed, which is conducive to long-term maintenance of machine tool accuracy.

Large machine tool casting cleaning, bed casting cleaning is the essence of the maintenance of the casting, the purpose of cleaning is to make the casting surface quality can be improved. Casting melting and pouring iron quality on the surface quality of castings is mainly reflected in two aspects, one is the content of impurities in the water, especially the content of iron oxide, which is very easy to produce slag or slag pores on the surface of the casting; the second is the gas content in the iron, high gas content is easy to make the casting in the surface or subcutaneous pores. The main measure we take is to increase the temperature of the iron, establish a perfect cupola detection system to ensure that the cupola is in normal condition.   "High temperature resting, low temperature pouring" is the control guideline of pouring, in order to reduce the casting porosity, shrinkage and surface sticky sand defects. Improve the level of casting technology, improve the export of machine tool castings surface quality   Reasonably determine the parting surface as much as possible to reduce the parting surface to reduce the formation of the parting surface of the flying edge, surface bump and other casting surface defects; improve the integrity of the core, reduce the number of joints between the core, reduce the gap between the core or core and type, in order to improve the surface convexity and clarity of the contour of large castings. The selection of process parameters has a great influence on the dimensional accuracy and contour clarity of the casting. After many process tests, each process parameter is carefully selected.   Extensive application of the latest casting process results to improve the level of casting technology to reduce casting defects, especially casting surface defects.

(1) CNC unit   CNC unit is the core of CNC machine tools, CNC unit consists of information input, processing and output of three parts. CNC unit accepts digital information, after the control software and logic circuit of the CNC device for decoding, interpolation, logic processing, will be a variety of instruction information output to the servo system, the servo system to drive the executive parts for the feed movement. Others are the main moving parts of the variable speed, reversing and start-stop signal; selection and exchange of tools tool command signal, cooling, lubrication start-stop, workpiece and machine parts loosening, clamping, indexing table rotation and other auxiliary command signal.   (2) Servo system   By the driver, drive motor, and with the machine tool on the implementation of the components and mechanical drive components of the CNC machine tool feed system. Its role is to convert the pulse signal from the CNC device into the movement of the moving parts of the machine tool. For stepper motors, each pulse signal makes the motor turn an angle, which in turn drives the machine tool moving parts to move a small distance. Each feed motion of the executive components have the corresponding servo drive system, the performance of the entire machine depends mainly on the servo system. (3) Position feedback system   Servo motor feedback of the angular displacement, CNC machine tool actuator (table) displacement feedback. Including grating, rotary encoder, laser rangefinder, magnetic scale, etc.   Feedback device to detect the results into electrical signals back to the CNC device, through comparison, calculate the deviation between the actual position and the command position, and issue deviation instructions to control the feed movement of the executive components.   (4) mechanical components of the machine tool   For the machining center class of CNC machine tools, and storage tool magazine, tool exchange robot and other components, CNC machine tool mechanical components and ordinary machine tools are similar, but the transmission structure requirements are more simple, in terms of accuracy, rigidity, vibration resistance and other requirements, and its transmission and speed change system is more convenient to achieve automation expansion.

Today I give you the steps to go through to machine a part on a CNC machine. (1) Preparation stage   Based on the drawing of the machined part, determine the relevant machining data (coordinate points of the toolpath, cutting dosage for machining, tool size information, etc.) and select the relevant other auxiliary information according to the process plan, the selected fixture, the type of tool, etc.   (2) Programming stage   According to the processing process information, with the machine tool CNC system can recognize the language to write CNC machining program (description of the processing process), and fill out the program sheet. (3) Prepare the information carrier   According to the program list has been compiled, the program stored in the information carrier (perforated tape, tape, disk, etc.), through the information carrier will be all processing information to the CNC system. If the CNC processing machine tools and computer networking, the information can be loaded directly into the CNC system.   (4) processing stage   When the implementation of the program, the machine tool numerical control system will process the program statement decoding, computing, into the drive of the moving parts of the action instructions, in the unified coordination of the system to drive the timely movement of the moving parts, automatically complete the processing of the workpiece.

The operation of machinery and equipment is simple and complex. Simple because of the pre-programmed compiled and executed, complex because it requires professional rigorous operation, mechanical equipment testing and maintenance is also the same. The following I will introduce you to the general knowledge of mechanical equipment testing and maintenance. 1、Through the training of employees, make them familiar with the basic operation techniques of equipment maintenance and equipment use to avoid equipment failure or damage caused by improper operation;   2、Training specialized technical personnel, familiar with the construction of equipment and fault diagnosis, troubleshooting and overhaul techniques;   3, collect and summarize the experience of equipment management to improve the efficiency of the use and management of equipment.   For preventive equipment overhaul and maintenance, the purpose is to maximize the utility of the equipment with minimum equipment maintenance costs, so it is essentially a matter of choosing the best maintenance cost and benefit-price ratio. This is both a management problem and an optimization problem. This problem is more focused on the timing of the maintenance and overhaul schedule of the equipment. In the process of using the equipment, it is affected by the temperature and humidity of the working environment, the continuous running time, the age of the equipment, the material of the equipment, etc. This requires the maintenance personnel to analyze the health condition of the equipment operation through the situation reflected in the actual use of machinery and equipment, so as to make a reasonable schedule of daily maintenance and downtime repair of the equipment in due time. The effect of this should be firstly to avoid unnecessary downtime, and secondly to achieve the daily maintenance of the equipment without affecting the normal operation of the equipment as far as possible, and to deal with the abnormal conditions found in time.

Precision parts processing is a complex and rigorous process, is a combination of each step of the processing process, so what are the specific points of the production of precision parts processing? The following is my introduction to you. The production process of the machine is the whole process of making the 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. Modern enterprises use the principles and methods of system engineering to organize and guide production, and view the production process as a production system with inputs and outputs.   In the production process, any process that changes the shape, size, location and nature of the production object to make it a finished or semi-finished product is called a process. It is the main part of the production process. Processes can be divided into casting, forging, stamping, welding, machining, assembly and other processes, machinery manufacturing process generally refers to the sum of the mechanical processing process of parts and machine assembly process, other processes are called auxiliary processes, such as transportation, storage, power supply, equipment maintenance, etc.. Processes are composed of one or several sequential processes, a process consists of a number of work steps. Precision parts machining process process is the basic unit of the composition of the machining process. The so-called process refers to a (or a group of) workers, in a machine tool (or a workplace), on the same workpiece (or at the same time on several workpieces) by the continuous completion of that part of the process. The main characteristic of a process is not to change the processing object, equipment and operator, and the content of the process is completed continuously.

The casting process of machine tool bed casting is very delicate, especially the temperature is particularly delicate, so in the end what are the essentials to be noted by the operator? The following is my introduction to the machine tool bed casting casting casting process:. In production, pouring should follow the principle of high temperature out of the furnace, low temperature pouring. Because the increase of the metal liquid furnace temperature is conducive to the thorough melting of inclusions, slag floating, easy to clear slag and gas, reduce machine tool castings slag and porosity defects; using a lower pouring temperature, it is conducive to reduce the dissolution of gas in the metal liquid, liquid shrinkage and high temperature metal liquid baking on the surface of the cavity, to avoid the production of porosity, sticky sand and shrinkage and other defects. Therefore, under the premise of ensuring the cavity is filled, try to use a lower pouring temperature.   The process of injecting the metal liquid from the casting ladle into the mold is called pouring. Improper pouring operation will cause under-pouring, cold space, porosity, shrinkage and slag and other machine tool casting defects, and cause personal injury.   In order to ensure the quality of machine tool castings, improve productivity and to achieve safe production, pouring should strictly comply with the following operating principles. (1) pouring package, pouring tools, furnace pre-treatment of breeding agent, spheroidizing agent, etc. must be fully dried before use, after drying before use.   (2) The pouring personnel must wear working clothes and protective glasses as required, and the workplace should be free from obstruction. The metal liquid in the pouring ladle should not be too full, so as not to overflow and injure people when conveying and pouring.   (3) The correct choice of pouring speed, that is, the beginning should be slow pouring, to facilitate the alignment of the gate, reduce the impact of molten metal on the sand and facilitate gas discharge; then fast pouring, in order to prevent cold isolation; almost full before pouring and should be slow pouring, that is, follow the principle of slow, fast, slow.   (4) for liquid shrinkage and solidification shrinkage is relatively large machine tool castings, such as medium and large cast steel parts, pouring in time from the gate or riser to fill the pouring.   (5) pouring should be promptly cast in the gas bubble ignition paragasms, so as not to produce pores due to the cast holding air, as well as incomplete combustion of gas and damage to human health and pollution of the air.

Defect repair of machine tool castings: The results of repair of several traditional welding repair processes at machine tool casting defects are analyzed to determine the reasons for the poor repair results of machine tool castings. By studying the repair results of casting defect repair machines in machine tool castings, a new technology and its process for repairing on machine tool castings is determined to be indeed feasible. 1、Spray welding   According to the execution of the spray welding process, the guide surface will be preheated to more than 150 ℃, after completing the initial spraying of welding powder, the spraying surface will be heated to more than 900 ℃ - 1200 ℃, so that the welding powder melted to form a flat surface. Because of the preheating and heating time is long, the workpiece is heated area is larger, the thermal stress is larger, more likely to produce cracks than arc welding, while the line shrinkage has a greater tendency to produce cracks. As the cracking tendency is affected by the spray welding time, spray layer thickness and other factors, the size of the defect is somewhat limited, and the defect needs to be cleaned up, due to the high proportion of fe in the spray powder, the formation of the spray layer is more similar to the color of the base material than arc welding. But because of a certain amount of ni, so can not be closer to the color of the parent material, welding can be machined after repair.   2、Arc welding   Weld with cast iron welding rod z248, welding process is divided into two kinds, the first: preheating to 550 ℃ -650 ℃ before welding, welding after the insulation 5-8 hours; the second: the workpiece is not preheated before welding, after welding insulation 3-4 hours. Both methods are prone to cracks, hard spots, welding repair after the mechanical processing is not easy. The welding rod is cheap. With nickel-based cast iron welding electrode z308 welding electrode welding, welding layer and welding layer should be paused between cooling to 60 ℃ or less, welding patch area less porosity, cracking, good machinability, high bond strength, no shedding phenomenon, due to the machine tool guide processing oil absorption and welding rod blowing force, easy to produce biting, the formation of "welding patch marks", welding patch area Color and the parent material is very different, and the price of welding rod is expensive. From the analysis of the results can be derived: the traditional welding repair process can not completely solve the machine tool guide defects repair the fundamental reason is the unified spray welding, arc welding process, welding repair is easy to produce cracks, the workpiece is susceptible to heat deformation, easy to appear secondary porosity, welding repair at the metal color and the parent material difference is its common characteristics.