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

During the processing of hardware parts, there will be some problems that affect the accuracy. So what are the factors that affect the accuracy of machining? Let's take a look at it together:   The original error of the process system: the geometric error of the process system, such as the processing principle error, the geometric accuracy of the machine tool, the manufacturing error of the tool and the fixture, the installation error of the workpiece, etc. The mechanical deformation of the process system, thermal deformation, and errors caused by internal stress will affect the accuracy of parts processing. Processing principle errors such as approximate processing of production, forming processing, etc., as long as the processing principle errors are limited within the allowable tolerance, productivity can often be greatly improved.   The error of the geometric accuracy of the machine tool for the processing of hardware parts, such as the radial and axial runout error when the spindle rotates. The straightness error of the machine tool guide rail in the horizontal and vertical directions, and the parallelism error between the guide rail and the guide rail. Errors in the machine tool drive chain.   The tool error measurement error of hardware parts processing, the thermal deformation error of the process system. The thermal deformation of the workpiece and the tool, cutting heat, friction heat, incidental heat, etc., so many precision machine tools are placed in the Tanwen workshop, (slow wire machine, CNC machine tools, etc.). The deformation caused by the internal stress of the workpiece includes the cutting process. The residual stress in the workpiece causes plastic deformation of the workpiece.   Therefore, in order to reduce the machining accuracy caused by the original error, we usually think of self-turning, self-milling, self-grinding, and self-cutting of the machine tool to try to restore the machining error caused by the original error. For example, the parallelism, perpendicularity and flatness of each surface of aluminum alloy products with a shape of 200*20*400 are processed by the old milling machine, and the flatness is within 0.03. The old wire-cutting machine tools process sets of parts with inner and outer circle coaxiality within 0.02, etc. When we think that the machining accuracy is uncontrollable, we must think of adopting self-turning, self-milling, self-grinding, These methods are self-cutting to lift.

The level of machining accuracy of stainless steel parts is determined according to the requirements of use. The machining of aerospace parts requires high precision, while the parts on tractors may require relatively low requirements. The cost of the parts is closely related to the machining accuracy. The 7-level precision should be relatively high precision. Going up, such as 6-level, 5-level, and 4-level, is a higher precision. For each additional precision level, stainless steel parts are processed. The difficulty of processing will increase geometrically, and the requirements for processing machine tools and tools will be higher, and workers will also be required to have a higher level of processing.   For example, the 7th grade precision of stainless steel parts can be achieved with general machine tools and tools, but the 6th grade requires a grinder, and the 5th grade requires CNC machine tools and fine grinding, or even manual grinding, and the 4th grade is even more. Disaster. For each additional level of accuracy, there may be several more processes, several better machine tools, and many more skilled workers, so the cost of parts will increase a lot. In this way, a problem of processing economic precision is raised, that is, the parts with this precision are suitable and economical to use in a certain occasion. For example, for a certain part on a tractor, level 11 accuracy is enough. Of course, it is better to process it to 5 precision, but the cost of level 11 may only be 10 yuan, but the cost of level 5 may be 100 yuan or more. , is bad for the factory. Therefore, the so-called economic accuracy is the lowest accuracy and lowest cost under the conditions of meeting the requirements of use, so as to achieve the purpose of maximizing benefits. After my analysis, you should also be able to feel the relationship between it and the machining process specification. The process specification should be formulated according to economic accuracy.

In recent years, it has entered the field of ultra-precision parts processing technology. From the perspective of development, it will play a greater role in the next century. Today's EDM is close to the level of ultra-precision machining in terms of its function and machining quality. Taking WEDM as an example, by using secondary cutting, the cutting accuracy is ±2μm, which can achieve high surface quality. ; From a development point of view, ultra-precision machining technology has been advancing to a higher level, so its definition is also difficult to determine, and the accuracy has continued to improve over time, and metrology is the first to bear the brunt. The main features of precision parts processing are precision automatic lathes, with five sets of tool rests, which are respectively equipped with micro-card fine-tuning to achieve high precision of the workpiece; more than 10 tools can be installed according to the workpiece processing process. Two-axis device; the main shaft adopts an electromagnetic clutch, which drives the tapping main shaft, and uses the high-speed rotation and the rotation difference of the mechanical main shaft in the same direction to carry out the tapping. Precision parts processing technology is a comprehensive system engineering. Its development makes comprehensive use of the progress of machine tools, tools, measurement, environmental technology, microelectronics technology, computer technology, numerical control technology, etc. It is an important means for science and technology to develop to a higher level, and it is also a key technology that must be broken through at this stage.

1. The part of the process that one or a group of workers continuously complete on one or several workpieces at the same place is called the process. 2. The basis for dividing the process is whether the working place changes and whether the work is continuous. 3. The part of the process content that is completed continuously when the processing surface and processing tools remain unchanged is called a work step. 4. Process information refers to all kinds of information obtained after process processing. Process preparation tool selection, processing scheme, compensation scheme and other information. 5. The accumulation of practical experience in processing is an effective way to obtain process information. 6. The basis for dividing work steps is whether the machining surface and tools are changed.

(1) Select and determine the content of CNC machining; (2) Analyze the process of CNC machining for the part drawing; (3) Mathematical processing of part graphics and determination of programmed dimension setting value; (4) Formulation of CNC machining process plan; (5) Determination of work steps and feeding routes; (6) Select the type of CNC machine tool; (7) Selection and design of cutting tools, fixtures and measuring tools; (8) Determination of cutting parameters; (9) Preparation, verification and modification of processing program; (10) First piece trial processing and handling of on-site problems; (11) Finalization and filing of CNC processing technology documents.

Machining parts on an automatic CNC lathe usually goes through the following steps: 1. According to the drawings and process plans of processed parts, compile the program sheet with the specified code and program format, and record it on the carrier. 2. Input the program on the program carrier into the CNC unit through the input device; 3. After processing the input program, the CNC unit sends signals to the servo system of each coordinate of the machine tool; 4. The servo system drives the moving parts of the machine tool and controls the auxiliary operation according to the signal sent by the CNC unit; 5. Drive the relative movement between the cutter and the workpiece through the mechanical parts of the machine tool to process the required workpiece; 6. Detect the movement of the CNC lathe and feed it back to the CNC unit through the feedback device to reduce the machining error. Of course, there is no detection and feedback system for open-loop CNC lathe.

1. The type, specification and accuracy grade of NC cutting tools shall meet the machining requirements of CNC lathes. 2. High accuracy. In order to meet the requirements of high precision and automatic tool change in NC lathe machining, the tool must have high precision. 3. High reliability. In order to ensure that accidental damage and potential defects of tools will not occur in NC machining, which will affect the smooth progress of machining, the tools and their combined accessories must have good reliability and strong adaptability. 4. High durability. The durability of cutting tools made of different materials is also different, such as: cemented carbide cutting tools; High speed steel cutting tools; Diamond cutting tools, etc. The cutting tools processed by CNC lathes, whether in rough machining or finish machining, should have higher durability than those used by ordinary lathes, so as to reduce the number of tool replacement or grinding and tool setting, so as to improve the processing efficiency of CNC lathes and ensure the processing quality. 5. Good chip breaking and chip removal performance. In CNC lathe processing, chip breaking and chip removal can not be handled manually in time like ordinary machine tool processing. Chip is easy to wrap around the tool and workpiece, which will damage the tool and scratch the machined surface of the workpiece, and even hurt people and equipment accidents, which will affect the processing quality and the safe operation of the machine tool. Therefore, the tool is required to have good chip breaking and chip removal performance.

In the process of CNC machining, the selection of cutting tools is a very important link. Choosing the right tool can not only greatly improve the processing efficiency of the machine tool, but also improve the processing quality of parts. Choosing the wrong tool will result in half the effort, and even scrap parts.   Compared with ordinary machine tools, the spindle speed of CNC lathe is much higher, and it has larger output power. For this reason, compared with the traditional processing technology, CNC machining is more strict in the selection of cutting tools. This harshness is mainly reflected in the accuracy, strength, rigidity and durability of the tool. In addition, NC tools also need to have stable dimensions to facilitate installation and V-letter: ug5209 receive free CNC course adjustment.   This requires CNC tools to have reasonable structure, standardized and serialized geometric parameters. In order to improve the processing and marketing of CNC lathes, efficient and stable CNC tools are one of the prerequisites. How to choose CNC tools mainly depends on the following aspects: the geometry of the machined parts, the state of the material, the rigidity of the fixture and the tool selected by the machine tool.

Human failure refers to the failure caused by the operator and maintenance personnel who are not familiar with the CNC machine tool or do not deal with it properly when making or adjusting it according to the requirements of the manual. Hard failure refers to the failure caused by the damage of the hardware of the CNC machine tool.   Soft failure generally refers to the failure caused by the syntax error, logic error or illegal data in the CNC machining program, the error in the parameter setting or adjustment of the CNC machine tool, the battery of the RAM chip is open circuit, short circuit and poor contact, and the RAM chip cannot get the voltage to maintain the data, resulting in the loss or error of parameters and processing programs, and electrical interference jumping into the bus, CNC machine tool failure caused by timing error and other reasons.

In order to use the CNC milling machine correctly and reasonably and ensure the normal operation of the machine tool, it is necessary to formulate a relatively complete operation plan for the CNC milling machine, which should generally be: (1) After the machine tool is powered on, check whether the switches, buttons and keys are normal and flexible, and whether the machine tool has abnormal phenomena. (2) Check whether the voltage, air pressure and oil pressure are normal, and manually lubricate the parts with manual lubrication first. (3) Each coordinate axis returns to zero manually (return to the reference point of the machine tool). If an axis has zero position before returning to zero, you must move the axis a certain distance from the zero point before returning to zero. (5) During the rotary exchange of worktable, there shall be no foreign matters on the worktable, shield and guide rail. (6) After the program is input, it should be carefully checked to ensure that it is correct. (7) Compact process stacking and installation of alignment fixture. (8) Before installing the workpiece, run the program empty once to see whether the program can be executed smoothly, whether the tool length is taken first, whether the fixture installation is complete, and whether there is over travel. (9) Input the workpiece coordinates to the offset page, and carefully check the coordinate value, sign and decimal point. (10) After the tool compensation value (tool length and radius) is entered into the offset page, it should be carefully checked. (11) When clamping tools, pay attention to whether the screw pressing plate hinders the movement, and check the part blank and abnormal size. (12) For parts processed for the first time, the first piece must be tested for the classified drawing process, procedure and tool adjustment card. (13) In the process of program operation, we should focus on observing several displays on the CNC system; ① Coordinate display (POS key), you can know the position of the tool motion point before stopping in the machine coordinate and workpiece coordinate system. Understand the displacement of the program paragraph and how much displacement theory is left; ② The program display (progm key) shows that the status instructions of the program segment and the next few program contents are being executed. ③ Simulation display (press graph key), you can see the graphic display of the tool path. (14) During trial cutting and processing, after sharpening the tool and replacing the tool accessories, the tool length should be renewed and the tool compensation value should be modified. (15) When removing fixtures, some fixtures should record the installation position and orientation, and make records for archiving. (16) Cut off the power supply as required. (17) Clean the machine tool. (18) Fill in the empty shift record book carefully and do a good job of shift handover.