RU2554142C1 - Method of turning of caprolon blanks - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: blank and cutting tool are provided with relative movement ensuring shaping, and feed is performed by steps. The caprolon blank is subjected to preliminary treatment by the ball. The caprolon blank is cut to cutting depth considering value of elastic recovery of the ball deformed surface layer of the caprolon.

EFFECT: increased accuracy of dimensions and shape of the treated surface.

1 dwg

Description

The invention relates to the processing of materials by cutting and can be used in the machining of plastic blanks, mainly from caprolon.

There is a method of mechanical processing, for example turning, of plastic blanks, for the implementation of which a special cutting tool equipped with hard alloys is used (V.N. Poduraev. Cutting of hard-to-work materials: Textbook for universities. - M.: Higher School, 1974, p. 574).

However, the implementation of this method does not provide a high-quality surface after processing due to the presence of significant differences in the physicochemical properties of metals and plastics. In this case, a significant surface roughness is formed, the elements of which create stress concentrators, which negatively affect the strength characteristics of the finished part as a whole.

The closest analogue is the method of turning the caprolon blanks, in which the relative motion of forming is reported to the blank and the cutting tool, and feeding is carried out discretely, while the caprolon blank is subjected to preliminary processing (New materials and technologies in mechanical engineering 2010. 11th International Scientific and Technical Conference 1. Materials and technologies in mechanical engineering - Study of cutting forces during turning of polymeric materials after preliminary surface deformation otovok. Kalita EG (Togu, Khabarovsk, RF), 2010).

However, the known method does not allow to ensure the accuracy of the size and shape of the processed surface, since the cutting depth during turning of the workpiece is assigned without taking into account the magnitude of the phenomenon of “elastic aftereffect” of caprolon, which occurs after preliminary processing of the caprolon blank with a ball.

The technical problem to which the invention is directed is to increase the accuracy of the dimensions and shape of the treated surface.

This problem is solved in that in a method comprising turning the caprolon workpieces, in which the workpiece and the cutting tool are informed of the relative shaping movement, and the feeding is carried out discretely, while the caprolon workpiece is pre-treated with a ball, according to the invention, the caprolon workpiece is cut to a depth cutting, taking into account the magnitude of the elastic recovery of the deformed ball of the surface layer of caprolon.

Pretreatment of a caprolon billet by surface deformation by rolling in a ball reduces the strength of the caprolon surface layer by 8-11%, thereby improving the quality of the surface being machined and there are prerequisites for increasing the cutting speed and technological process productivity. In this case, the appointment of the depth of cutting of caprolon, taking into account the magnitude of the elastic aftereffect, after preliminary processing of the surface of the workpiece with a ball, ensures high accuracy of the size and shape of the surface machined by turning, since the cut line is located in that part of the material in which part of the bonds are broken and part is stressed. This allows the main crack to stably propagate along the shear line without significant deviations from it.

The method of turning the blanks from caprolon is illustrated in the drawing, which shows a diagram of the preliminary processing of caprolon ball.

An example implementation of the method.

The blank of caprolon 1 is fixed in a lathe in a known manner. Then, pre-treatment of the caprolon preform is carried out by surface deformation by rolling around with a ball 2.

In this case, a material structure is formed in which part of the bonds is broken, and part is strained and has a low activation energy of bonds, which contributes to the breaking of some of the excited bonds in polymer chains by thermal fluctuations. Then, the workpiece is cut with a conventional tool, assigning the cutting depth t _{p of} caprolon 1, taking into account the value of t _{g of} elastic recovery of the ball surface deformed by the ball t _{d of} caprolon. Due to the fact that cutting occurs below the boundary t _{d of} broken bonds (the allowance for processing caprolon is increased), the quality of the processed surface increases, and the roughness decreases.

In this case, the modes of rolling around the ball 2 and the cutting depth t _p are established experimentally, depending on the size of the blank from caprolon 1.

Unlike analogues, the proposed method allows to ensure the accuracy of the size and shape of the processed surface, since the cutting depth during turning of the workpiece is assigned taking into account the magnitude of the phenomenon of “elastic aftereffect” of caprolon, which occurs after preliminary processing of the caprolon blank with a ball.

Claims (1)

The method of turning blanks from caprolon, in which the relative motion of forming is reported to the blank and the cutting tool, and the feeding is carried out discretely, while the blank from caprolon is pre-treated with a ball, characterized in that the caprolon blank is cut to a depth of cut taking into account the amount of elastic recovery of the deformed ball surface layer of caprolon.

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