The treatment accuracy refers to the extent in which the real geometric parameters (dimensional, shape and position) after the treatment of the part comply with the ideal geometric parameters specified in the drawing. The higher the degree of conformity, the higher the treatment accuracy.
In the treatment, due to the influence of various factors, it is in fact impossible to treat each geometric parameter of the room to be completely consistent with the ideal geometric parameter, and there will always be differences. This gap is to treat the error.
Discussed the following three aspects:
1 and 1 methods to obtain partial dimensional precision
2 methods to obtain the precision of the form
3 and 3 how to obtain the accuracy of the position
1 and 1 methods to obtain partial dimensional precision
(1) Test cutting method
In other words, first try to cut a very small part of the processing surface, to measure the size obtained by cutting the test, adjust the position of the point tool compared to the part depending on the processing requirements , then try to cut and then measure.
The test cutting method is repeated by the “cutting of the award-up-retest-retest-adjustment of the cutting cut” until the required dimensional accuracy is obtained. For example, the treatment of the box systems of box systems.
The accuracy obtained by the test cutting method can be very high, it does not require complex devices, but this method takes time (requires multiple adjustments, a cut, a measurement and a calculation), and depends the technical level of workers and the precision of the measurement instrument.
As a type of test cutting method, it is a processing method of another part which corresponds to it as a function of the treated parts, or combination of two (or more) treatment parts. The requirements for the size of the final treatment during assembly are subject to correspondence requirements with the parts processed.
(2) Adjustment method
Use standard samples or parts to adjust the exact relative positions of machine tools, lighting, tools and parts in advance to ensure the dimensional precision of the room. Since the size is adjusted in place in advance, it is not necessary to try to cut during treatment, the size is automatically obtained and remains unchanged during the treatment of a batch of parts. For example, when using a grinder luminaire, the position of the tool is determined by the tool block. The essence of the adjustment method consists in using the device or the adjustment device of the fixed-range tool on the machine-tool or the preinstalled tool support so that the tool reaches a certain position accuracy compared to at the machine-tool or in the light, then to treat a lot of the parts.
The injection and cut depending on the dial on the tool-tool is also a kind of adjustment method. This method first requires determining the scale on the dial as a function of the test cutting method. In mass production, regular judgments, samples, samples, etc. are often used to adjust the tools of the tool.
The adjustment method has good machining precision and good stability, high productivity and does not require high machine tool operators, but has high requirements for machine tool adjustment workers and is often used in batch production and mass production.
(3) Size method
The method of using the corresponding size of the tool to ensure that the size of the part to be treated is called the fixed size method. It uses the treatment of standard size tools and the size of the processing surface is determined by the size of the tool. In other words, the tools with a certain dimensional precision (such as the bores, the bore exercises, the forests, etc.) are used to ensure the precision of the part to be treated (like holes).
The fixed size method is practical for operating, has high productivity and a relatively stable treatment accuracy. For example, drilling, bore, etc.
(4) Active measurement method
During the processing process, the processing dimensions are measured during treatment, and the results measured are compared to the size required by design, or the tool-tool continues to operate or stop working.
Currently, the values of active measurements are available to display numbers. The active measurement method adds the measurement system to the process system (i.e. the integration of machine tools, tools, lighting and parts), becoming its fifth factor.
Active measurement methods have a stable quality and high productivity, which is the development management.
(5) Automatic control method
This method consists of a measurement device, a power device, a control system, etc. It combines the measurement device, the power device and the control system in an automatic processing system, and the processing process is automatically finished by the system.
A series of tasks such as dimensional measurement, adjustment of tools compensation and cutting treatment and machine tool parking is automatically completed to automatically reach the required dimensional precision. For example, when treating CNC machine tools, parts are controlled by various program instructions.
There are two specific methods for automatic control:
① The automatic measurement means that there is a device that automatically measures the size of the part on the tool-tool.
② Digital control means that there is a servomotor, a pair of vision nut and a complete set of digital control devices which control the precise movement of the tool support or the installation in the machine tool. The workbench move) is based on a pre -programmed program.
The initial automatic control method was completed using active measurement systems and mechanical or hydraulic control. Currently, pre-arranged programs based on processing requirements have been largely adopted. and can adapt to changes under processing conditions during the processing process, and automatically adjust the use of treatment and carry out the adaptive control machine tool to optimize the processing process according to the conditions prescribed to carry out the automatic control of control.
The automatic control method has stable quality, high productivity, good treatment flexibility and can adapt to several varieties of production.
2 methods to obtain the precision of the form
(1) Trajectory method
This treatment method uses the tip of the blade to form the shape of the surface to be treated. Ordinary turn, crushing, crushing, rotation and grinding are all part of the tool’s trajectory method. The precision of form obtained in this method depends mainly on the precision of the training movement.
(2) Training method
The geometry of the training tool is used to replace certain training movements of the tool-tool to obtain the form of machining surface. Like turning, milling, grinding, etc. The precision of form obtained by the training method depends mainly on the shape of the blade.
(3) Development method
The shape of the treatment surface is obtained using the tool and the part to develop in an envelope surface formed by moving the tool to obtain the shape of the treated surface. all developed. The precision of form obtained by this method depends mainly on the precision of the form of the blade and the precision of the movement of expansion.
3 and 3 how to obtain the accuracy of the position
In mechanical treatment, the accuracy of the treatment surface to other surface positions depends mainly on tightening the part.
(1) Find the formal clip directly
This method is a tightening method that uses a dial table, a splitting plate or visually determines the position of the part directly on the machine tool.
(2) Grignage and find formal pliers
This method consists in first drawing the central line, the symmetry line and the treatment lines of each surface to be treated according to the drawing room on the white, then install the part on the machine tool and align the position of Part tightening on the machine machine according to the marked lines.
This tightening method has low productivity, low precision and high technical requirements for workers. Directly tight with lighting.
(3) Lighting
The luminaire is specially designed according to the requirements of the process to be processed. .
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