RU2626124C1 - Method of magnetic-abrasive polishing of work areas of taper tap - Google Patents

Abstract

FIELD: machine engineering.

SUBSTANCE: stepwise processing of the intake, calibrating and leading work areas of a taper tap with its forward and reverse rotation in the magnetic-abrasive mass. At the first stage, all working sections of the taper tap are processed for a time period necessary to obtain the lowest values of microgeometric parameters in one of the three work areas. At the second stage, one of the two remaining work areas is refined to obtain the required values or the limits of the microgeometric parameters of the area. And the processing time is established in terms of the lowest values of microgeometric parameters of one of the two work areas of the taper tap. At the third stage, the remaining work area is refined to the required values or limits of the microgeometric parameters for the time period necessary for the final formation of the microgeometry of this area.

EFFECT: sudden drops of the values of microgeometric parameters in the transition zones are excluded, the durability of taper taps is increased and the quality and accuracy of the produced thread is improved.

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Description

The invention relates to magnetic abrasive polishing of complex tools.

A known method of magnetic abrasive polishing of complex surfaces (Baron Yu.M. "Technology of abrasive processing in a magnetic field." - L.: Mechanical Engineering. 1975, p. 79.), in which the part is placed between the poles of the magnetic system and ask her rotational and oscillating motion in a medium of magnetic abrasive mass.

The disadvantage of this method is the lack of a specific technological sequence when processing complex surfaces with various sections.

A known method of magnetic abrasive polishing of a tap (patent No. 2569261, publ. November 20, 2015), which is carried out by sequential processing of the intake, calibrating and leading working sections of the cutting tool. To keep the magnetic abrasive mass within the boundaries of the treated area, circular nozzles with nozzles through which air under a certain pressure enters perpendicular to the axis of the tap are used. The ability to control air pressure allows you to control the magnetic abrasive mass within the boundaries equal to the lengths of the working sections of the tap.

The disadvantage of this method is the inability to accurately control the magnetic abrasive mass in the processing zones of the working sections of the tap. The proposed method, although it sets the task of minimizing the distortion of already machined surfaces, does not completely solve this problem. All this leads to the fact that in the transition zones from one working area to another, increased microgeometric parameters are formed, which adversely affect the durability of the cutting tool and the quality of the cut thread.

A known method of magnetic abrasive polishing (US patent No. 5775976 A, publ. 07/07/1998), in which in order to increase the removal rate of the metal, it is proposed to use special nozzles for supplying a vacuum into the working area between the magnetic abrasive powder and the surface to be treated. The supply is carried out in such a way that the magnetic abrasive powder moves relative to the surface to be treated.

The disadvantage of this method is that the surface treatment is carried out simultaneously along its entire length. In this regard, the formation of microgeometric parameters of local areas, especially complex surfaces, is not possible.

A known method of magnetic abrasive polishing of the working areas of the tap (Baron Yu.M. "Magnetic abrasive and magnetic processing of products and cutting tools." - L .: Mechanical Engineering. 1986, p. 161-163.), With which form the radii of rounding of the cutting edges on the intake part and the fall of the back of the head on the leading part of the tool. This tap has a two-, three-fold advantage in resistance characteristics over standard taps designs and allows threading even in high-strength and difficult-to-work steels with one tap instead of a set of two or three taps.

The disadvantage is that not all functional features of the working areas of the tap are taken into account. In this regard, microgeometric parameters at different sites have the same values. This drawback does not allow the working parts of the tap to perform its intended functions in the general course of the threading process with a single-pass tap.

A known method of magnetic abrasive polishing of the working areas of the tap (Baron Yu.M., Maksarov V.V., Vasiliev V.G., Skripchenko V.I. “Improving the technology of threading in power engineering products” // Energomashinostroyenie, 1987, No. 1, pp. 24-27.), Adopted for the prototype, which is implemented in three stages, at the first stage, the formation of microgeometric parameters of the intake section is performed, at the second - calibrating, at the third - leading. The processing is performed with forward and reverse rotation of the threading tool in a magnetic abrasive mass.

The disadvantage of this method is that regardless of the sequence in which the working areas of the tap are processed using this method, whether it is an intake, calibrating, leading, or leading, calibrating, intake, or calibrating, intake, leading, or calibrating, leading, fence, etc., there is an increased magnetic abrasive effect on the transitional zones of adjacent work areas. As a result of this, in addition to variously formed microgeometric parameters, transition zones appear on three working sections of the tap, microgeometry of which is very different from microgeometry in the main sections of the tap. Sudden changes in microgeometric parameters throughout the entire working part of a thread-cutting tool lead to a decrease in the resistance of the thread-cutting tool and its premature failure, as well as to a deterioration in the quality of the thread being cut.

The technical result is to increase the resistance of the threading tool and improve the quality of the threaded surface with a single pass threading.

The technical result is achieved by the fact that at the first stage, all the working parts of the tap are processed with the time necessary for the formation of the smallest microgeometric parameters of one of the three working sections, at the second stage, the microgeometric parameters of one of the two remaining working sections are adjusted to the required values or limits, at this processing time is set based on the smallest microgeometric parameters of one of the two working sections of the tap, at the third stage, fine-tuning is performed microgeometric parameters of the remaining working area to the required values or limits with the time necessary for the final formation of the microgeometry of this area.

The method of magnetic abrasive polishing of the working areas of the tap is illustrated by the following figures:

FIG. 1 is a general diagram of magnetic abrasive polishing of the working areas of a tap;

FIG. 2 is a flowchart for magnetically abrasive polishing of the working sections of a tap;

FIG. 3 is a diagram of the formation of microgeometric parameters with the existing method of magnetically abrasive polishing of the working areas of the tap;

FIG. 4 - the values of the radii of rounding on the working sections of the tap with the existing method of magnetic abrasive polishing of the working sections of the tap;

FIG. 5 is a diagram of the formation of microgeometric parameters in the proposed method of magnetic abrasive polishing of the working areas of the tap;

FIG. 6 - the values of the radii of rounding on the working sections of the tap with the proposed method of magnetic abrasive polishing of the working sections of the tap, where:

1 - tap;

2 - pole tips;

3 - magnetic abrasive powder;

4 - electromagnetic coils;

5 - fence section;

6 - gage plot;

7 - leading section;

8 - the first zone of increased magnetic abrasive effects;

9 - the second zone of increased magnetic abrasive effects;

10 - the first transition zone;

11 - second transition zone;

t ₁ - the time of magnetic abrasive polishing with direct rotation of the threading tool in the magnetic abrasive mass at the first stage of the technological process;

t ₂ - the time of magnetic abrasive polishing during reverse rotation of the threading tool in the magnetic abrasive mass at the first stage of the technological process;

t _{argument 1} - lapping time of magnetic abrasive polishing with direct rotation of the threading tool in the magnetic abrasive mass at the second stage of the technological process;

t _{argument 2} - lapping time of magnetic abrasive polishing during reverse rotation of the threading tool in the magnetic abrasive mass at the second stage of the technological process;

t _{argument 3} - lapping time of magnetic abrasive polishing with direct rotation of the threading tool in the magnetic abrasive mass at the third stage of the technological process;

t _{argument 4} - lapping time of magnetic abrasive polishing during reverse rotation of the threading tool in the magnetic abrasive mass at the third stage of the technological process;

t ₃ - the time of magnetic abrasive polishing of the sampling area with the direct rotation of the threading tool in the magnetic abrasive mass with the existing method of magnetic abrasive polishing of the working sections of the tap;

t ₄ is the time of magnetic abrasive polishing of the gage section with the direct rotation of the threading tool in the magnetic abrasive mass with the existing method of magnetic abrasive polishing of the working sections of the tap;

t ₅ - the time of magnetic abrasive polishing of the leading section with the direct rotation of the threading tool in the magnetic abrasive mass with the existing method of magnetic abrasive polishing of the working sections of the tap;

l _RP - workspace;

δ is the working clearance;

t is the time of magnetic abrasive polishing;

ε - microgeometric parameters of the working sections of the tap;

n - working areas of the tap.

The method is as follows. The machined tap (1) is placed between the pole pieces 2 with a working gap 3 created by a magnetic system with electromagnetic coils 4. The working space l _{pr is} filled with magnetic abrasive powder 3, which is held and pressed against the processed surface by the action of magnetic field forces, copying it (Fig. 1). The rigidity of the formed magnetic abrasive mass can be controlled by changing the magnetic field strength in the working space l _pr Processing is performed with the forward and reverse rotation of the threading tool in a magnetic abrasive mass.

The method of magnetic abrasive polishing of the working areas of the tap is implemented in 3 stages. At each stage, the following is performed: the final formation of the microgeometric parameters of one of the machined sections of the tap; gradual formation of microgeometry in adjacent areas (Fig. 2).

At the first stage, the intake (5), calibrating (6) and leading (7) working sections of the tap (1) (Fig. 2) are simultaneously processed, while the time of magnetic abrasive polishing t ₁ and t ₂ corresponding to the forward and reverse rotation of the thread-cutting tool in a magnetic abrasive mass, set on the basis of the smallest required microgeometric parameters of one of the three working sections of the tap. The main goal of this stage is the final formation of microgeometry of the working area where, in comparison with the other two, it is necessary to create the smallest values of microgeometry. For the example of FIG. 2 this section is a fence (5).

At the second stage, the microgeometric parameters are adjusted to the required values (limits), while the finishing time of the magnetic abrasive polishing t _{argument 1} and t _{argument 2} , corresponding to the forward and reverse rotation of the threading tool in the magnetic abrasive mass, is set based on the smallest required microgeometric parameters one of the two remaining taps.

At this stage, it can be processed as one work area, or two at the same time. The number of sections subjected to processing depends on the technological sequence of the formation of microgeometric parameters at the working sections of the tap. If for example, as shown in FIG. 2, the microgeometric parameters of the intake section (5) are less than the microgeometric parameters of the calibrating section (6), and the latter, in turn, are less than the microgeometric parameters of the leading working section (7), then at the second stage, the calibration section (6) is refined and gradually formed microgeometry of the leading section (7), i.e. as a result, two work areas are simultaneously processed due to their adjacency. If the microgeometric parameters of the intake section (5) are greater than the microgeometric parameters of the calibrating section (6), and the latter, in turn, are less than the microgeometric parameters of the leading working section (7), then the final processing of the calibration section is carried out at the first stage, since this section has the least microgeometry in this case, at the second stage, one of the two remaining parameters is adjusted to the required microgeometric parameters, and at the last working ASTK, the second step in the process sequence is carried out without intermediate gradually forming operation. This nature of the action does not violate the basic principle of the proposed method.

The main goal of this stage is to bring the microgeometric parameters to the required values (limits), which are necessary for the final formation of microgeometry of the second working area. In our case, in FIG. 2 is a calibrating section (6).

At the third stage, the last working portion of the tap (1) is processed, while the magnetic abrasive polishing time t _{argument 3} and t _{argument 4} , corresponding to the forward and reverse rotation of the threading tool in the magnetic abrasive mass, is set in order to bring the microgeometric parameters of this working section to the required values (limits), which are necessary for the final formation of microgeometry of the third working portion of the tap. In our case, in FIG. 2 is the leading section (7).

In general terms, this method of magnetically abrasive polishing of the working sections of the tap can be characterized as follows: at the first stage, all working sections of the tap are always processed, at the second, either two working sections at the same time or separately, and if separately, the processing of one of them goes to the third stage (this feature depends on the technological sequence), the third is one, while the second and third stages are always finishing. The sequence of formation of microgeometric parameters of the working areas of the tap can vary and depends on which of the working areas it is required to generate the lowest values of microgeometry.

The proposed method of magnetic abrasive polishing of the working areas of the tap allows you to process the working areas without areas of high magnetic abrasive impact. This ability allows you to more clearly form the required microgeometric parameters that exclude sudden changes in transition zones. As a result of the application of this technology, the tool life increases, the quality and accuracy of the cut thread improves. Positive effects are caused by the fact that the working sections of a thread-cutting tool perform their direct functions in the process of threading with a single-pass tap.

Example. The task: to form the radii of rounding of the cutting edges on each of the working sections of the tap, while on the intake section the radius of the rounding of the cutting edges should be equal to 20 μm, in the calibration section - 28 μm, in the leading section - 38 μm.

The existing method of magnetic abrasive polishing of the working sections of the tap (Fig. 3, Fig. 4)

This method is implemented in three stages, at the first of which the sampling section (5) is processed, at the second - the calibrating section (6), at the third - the leading section (7), while the sequence of processing of the working sections can change. As a result of separate magnetic abrasive polishing of the working sections of the tap, zones of increased magnetic abrasive impacts 8 and 9 are noticeably distinguished, on which microgeometric parameters are formed, different from the parameters formed in adjacent working areas, which are different in zone 8 by t ₃ + t ₄ , and in zone 9 by the value of t ₄ + t ₅ (Fig. 3).

The values of the rounding radii at the work sites and in the areas of increased impact were set in the following values: on the intake site (5), the value of the rounding radii of the cutting edges to the zone of increased impact 8 was 20 μm. In the calibrating section (6), the value of the radii of rounding of the cutting edges from the zone of increased exposure 8 to the zone of increased exposure 9 was 28 μm. In the leading section (7), the radius of the rounding off of the edges from the zone of increased exposure 9 was 38 μm. In the zone of increased magnetic abrasive impact 8 itself, the value of the radii of rounding of the cutting edges was 33 μm, and the zone of increased exposure 9-44 μm (Fig. 4).

Formed microgeometric parameters in areas of increased magnetic abrasive effects 8 and 9 lead to quite serious fluctuations in microgeometry throughout the working part of the thread-cutting tool (Fig. 4), and in the areas of increased impact, these fluctuations can reach, as can be seen from Fig. 4, fairly high limits. Naturally, in the future, the indicated oscillations of microgeometry during threading have a significant effect on breaking the thread profile, reducing its quality, and also the variable loads acting on the working areas in local zones contribute to reducing the wear resistance of the thread-cutting tool and lead to its premature failure.

The proposed method of magnetic abrasive polishing of the working sections of the tap (Fig. 5 and Fig. 6)

Processing is carried out in three stages, at the first of which all the working sections of the tap are processed, at the second stage - calibrating and leading, at the third - leading. The processing sequence may vary, but the main thing is that the necessary condition is met under which the formation of microgeometric parameters is carried out from smallest to largest.

As a result of magnetically abrasive polishing of the working areas of the tap, zones of increased magnetic abrasive impact were not identified, and transition zones 10 and 11 were the beginning of the calibrating (6) and leading (7) working areas. The radii of rounding of the cutting edges in zones 10 corresponded to the radii of rounding of the cutting edges in the calibrating section and amounted to 28 μm, and the radii of rounding of the edges in zone 11 corresponded to the radii of rounding of the edges in the leading section and amounted to 38 μm (Fig. 6).

Claims (1)

The method of magnetically abrasive polishing of the working sections of the tap, including the stepwise processing of the intake, calibrating and leading working sections with forward and reverse rotation of the threading tool in the magnetic abrasive mass, characterized in that at the first stage, processing of all working sections of the tap is performed for the time required to form the smallest values of microgeometric parameters in one of the three working areas, at the second stage, one of the two remaining working areas is refined s until the required values or limits of the microgeometric parameters of the plot are formed, and the processing time is set based on the smallest values of the microgeometric parameters of one of the two working sections of the tap, and at the third stage, the remaining working section is adjusted to the required values or limits of the microgeometric parameters for the time required for the final formation of microgeometry of this site.

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