CNC precision machining of mating parts

1.Analysis of machining parts technology
We all know that the smallest unit in the machinery is the parts, and the mechanism is composed of parts to cooperate, machinery is the mechanism between the cooperation of the composition, a machine to be able to operate normally, play its corresponding role, then whether it can meet the requirements between the parts and parts to cooperate is the key to ensure its normal operation. With the rapid development of mechatronics, machinery manufacturing technology, CNC machine tools in the machining enterprise has been quite popular. Coupled with the requirements between the mating parts, the position accuracy of the parts, surface roughness and other requirements continue to improve, ordinary machine tools are difficult to achieve, then it is necessary to complete the CNC machine CNC precision Machining. The key to turning mating parts is the development of the machining process plan, the selection of the reference parts and the cutting process of the matching car and matching research. Reasonable development of the mating parts processing order and CNC precision Machining process can ensure the machining accuracy and assembly accuracy of the mating parts, and the machining accuracy of each part directly affects the assembly accuracy of the mating parts, of which the impact of the machining accuracy of the reference parts on the accuracy of the mating is particularly prominent. Therefore, in the development of the machining process scheme and combined machining of mating parts, the following points should be noted.

1.1. Determine the benchmark parts according to the assembly relationship of the mating parts.
1.2. When machining, the benchmark parts should be turned first, and then the remaining parts in the mating parts should be turned sequentially according to the assembly relationship.
1.3. Precautions when turning the reference parts.

(1). To focus on controlling the dimensional accuracy of the mating part.
(2). When turning a ball fit, the turning tool tip is equal to the axis of the ball center to avoid
The fit of the circular surface of the two parts does not meet the fit requirements.
(3). Threads should be turned into a shape, do not allow the use of plate teeth, tap processing.
(4). The sharp edges of the machined surfaces of the mating parts are blunted and cleaned.

According to the technical requirements and characteristics of the processed parts, as well as with the assembly requirements of the parts, respectively, the formulation of each part of the machining process, the number of times the main surface tooling (rough, semi-finish, finishing options) and cutting amount. Usually the reference surface should be processed first, followed by the rest of the surface on the part.

With the rest of the parts of the turning, first of all, should be in accordance with the requirements of the benchmark parts turning, followed by with the size should also be processed according to the benchmark parts and other parts of the actual results of the corresponding adjustment. Can also use with the car, with research and other means of processing to ensure the accuracy of the assembly.

  1. Parts processing

Equipment preparation

(1). Equipment power on, check the operation of the equipment.
(2). Manually return to the reference point to make sure the equipment is operating properly.
(3). Install the tool so that the position is correct and ensure that the tool center height is equal to the machine rotating spindle
(4). Set the workpiece coordinate system and tool parameters.
(5). Enter the program in the editing state, simulate the machining and debug the program to make sure the program
No error.

Part processing
(1). Install the part correctly, make the first test cut in the single-end state, and adjust the tool
and program parameters.
(2). Automatic machining of the part.
(3). Check the quality of the workpiece and clean it into storage.

  1. Parts inspection

Inspection of parts
Final inspection of the product according to the process inspection chart.
(1). The part’s outer diameter, inner diameter, groove, length, thread and other dimensional accuracy, can be used
The surface roughness can be inspected by using surface roughness measuring block.
(2). Focus on the accuracy of the test
(3) contact surface accuracy inspection

With the common coloring method and special R gauge test its spherical fit part, the specific method is: when processing the outer sphere with R gauge test; processing the inner sphere, due to measurement difficulties, the inner sphere surface coated with red powder, the outer sphere will be turned to match, and then remove the outer sphere, observe the sphere. When the part dyed red by the red powder is not less than 65%, it is qualified, otherwise it is not qualified.

(4) Inspection of coaxiality
Put the cylindrical surface of the workpiece benchmark on the V-frame, rotate the workpiece, measure the measured
cylindrical surface, read out the maximum reading and minimum reading difference shown by the micrometer pointer, and then divide by

is the coaxiality error.
(5) Inspection of verticality
Using the most simple method – the light gap method. Use the right angle ruler on the reference surface of the measured workpiece, check the gap between the measured surface of the workpiece and the right angle ruler, and use the stopper to detect the size of the gap. CMM can also be used to detect coaxiality error and perpendicularity error, and this instrument has high measurement accuracy. Specific measurement methods are explained in the knowledge expansion.

  1. Analysis of common problems
    (1). The accuracy of the circular fit is over poor
    Reason: The center of the spindle and the center of the turning tool are not equal in height; the turning tool tip arc R
    caused by the error of the arc; clamping the workpiece with too much error in finding the correctness.
    (2). The misalignment of the workpiece’s external surface after assembly is excessive
    Reason: When the machining part 1 was turned around for clamping, the alignment of the part was not allowed, resulting in the coaxiality of the outer surface and the inner arc surface being out of tolerance; the fit of the thread was out of tolerance; the dimensional accuracy of the outer and inner holes of each part was out of tolerance. After the inspection of the parts, we analyze the unqualified items, fill in the quality analysis form, find out the causes and point out the preventive measures. In summary, this paper discusses CNC precision machining of the mating parts, analyzes the machining process based on the part drawing, and determines the machining plan and cutting parameters for the part.

Through the correct operation of the machine tool, the machining program is run and the machining of the part is completed. When machining mating parts on CNC lathe, it is necessary to correctly select the appropriate CNC machine tool, to ensure the accuracy, but also to consider the economic and reasonable, to choose a reasonable fixture and clamping method, and to develop a reasonable process, in order to process the qualified parts.

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