There are mainly the following methods to obtain the accuracy of measuring the size of workpiece in the machining process of Guangdong Machinery Factory company
(1) Trial cutting method
Guangdong machining factory is to first try to cut a small part of the processing surface, measure the size of the test cut, adjust the position of the cutting edge of the tool relative to the workpiece according to the processing requirements, try to cut again, and then measure again. After two or three times of test cutting and measurement, when the size of the processed surface meets the requirements, then cut the whole surface to be processed. The trial cutting method is repeated through "trial cutting - Measurement - adjustment - trial cutting" until the required dimensional accuracy is achieved. For example, the trial boring of box hole system.
The precision achieved by the trial cutting method may be very high. It does not need complex devices, but this method is time-consuming (need to make multiple adjustments, trial cutting, measurement and calculation), low efficiency, and depends on the technical level of workers and the accuracy of measuring instruments. The quality is unstable, so it is only used for single piece and small batch production. Metal processing wechat, good content, worthy of attention!
As a type of trial cutting method, matching is a method of machining another matching workpiece or combining two (or more) workpieces together based on the machined workpiece. In the matching process, the requirements of the final machined dimension are based on the matching requirements of the machined parts.
(2) Adjustment method
Guangdong Machinery Factory adjusts the accurate relative position of machine tool, fixture, cutter and workpiece with sample or standard parts in advance to ensure the dimensional accuracy of workpiece. Because the size is adjusted in place in advance, when machining, there is no need to try again. The size is automatically obtained and remains unchanged during the processing of a batch of parts. This is the adjustment method. For example, when using the milling fixture, the position of the cutter depends on the cutter block. The essence of the adjustment method is to use the fixed distance device or tool setting device on the machine tool or the preset tool holder to make the tool achieve a certain position accuracy relative to the machine tool or fixture, and then process a batch of workpieces.
In the machine tool according to the dial feed and then cutting, is also a kind of adjustment method. This method needs to determine the scale on the dial according to the trial cut method. In mass production, tool setting devices such as range stop, sample piece and sample plate are often used for adjustment.
Compared with the trial cutting method, the adjustment method has better stability of machining accuracy, higher productivity, lower requirements for machine tool operators, but higher requirements for machine tool adjusters. It is often used in batch production and mass production.
(3) Sizing method
The method of using the corresponding size of the cutter to ensure the size of the workpiece is called sizing method. It uses the standard size of the tool processing, processing surface size is determined by the size of the tool. That is to use the cutter with certain dimensional accuracy (such as reamer, reamer, drill, etc.) to ensure the accuracy of the machined part (such as hole).
Sizing method is easy to operate, high productivity, processing accuracy is relatively stable, almost unrelated to the technical level of workers, high productivity, widely used in various types of production. Such as drilling, reaming, etc.
(4) Active measurement
In the process of machining, Guangdong machining factory measures the machining dimensions while machining, and compares the measured results with the dimensions required by the design, either to make the machine continue to work or to make the machine stop working. This is the active measurement method.
At present, the values in active measurement can be displayed digitally. The fifth factor of the active measurement method is to add the measuring device into the process system, which is the unity of machine tool, cutter, fixture and workpiece.
Active measurement is the development direction with stable quality and high productivity.
(5) Automatic control method
This method is composed of measuring device, feeding device and control system. It is the measurement, feed device and control system constitute an automatic processing system, the processing process depends on the system to complete automatically.
A series of work, such as dimension measurement, tool compensation adjustment, cutting and machine tool stop, are completed automatically to achieve the required dimension accuracy. For example, when machining on CNC machine tools, parts control the processing sequence and precision through various instructions of the program.
There are two methods of automatic control
① Automatic measurement means that there is an automatic measuring device on the machine tool to measure the size of the workpiece. When the workpiece reaches the required size, the measuring device will send a command to make the machine tool automatically retract and stop working.
② Digital control means that there are servo motors, rolling screw nut pairs and a complete set of digital control devices in the machine tool to control the precise movement of the turret or worktable. The acquisition of dimensions (the movement of the turret or worktable) is automatically controlled by the computer digital control device through the pre programmed program. Metal processing wechat, good content, worthy of attention!
The automatic control method in the early stage of Guangdong mechanical processing plant was completed by using active measurement and mechanical or hydraulic control system. At present, it has been widely used that the program arranged in advance according to the processing requirements, the program controlled machine tool that the control system sends instructions to work, or the digital controlled machine tool that the control system sends digital information instructions to work, and it can adapt to the changes of processing conditions in the processing process and automatically adjust the processing amount, According to the specified conditions to achieve the optimization of the processing process of adaptive control machine tool for automatic control processing.
At present, the development direction of mechanical manufacturing and the basis of computer-aided manufacturing (CAM) are based on the stable quality, high productivity, good processing flexibility and multi variety production of automatic control method.