RU2380212C1 - Method for processing of nonrigid shafts - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention is related to the field of metal forming, more precisely, to straightening with simultaneous finishing-strengthening processing by surface plastic deformation of nonrigid shafts. Preliminarily elastic deformation of nonrigid shaft is carried out, as well as straightening with simultaneous surface plastic deformation realised with continuous force of deforming tool moved along generatrix of nonrigid shaft that rotates around its central axis. Besides preliminary elastic deformation of nonrigid shaft is executed by application of transverse force at concave side of item in direction of deforming tool by a certain value. And straightening with simultaneous surface plastic deformation is executed in each cross section of nonrigid shaft with provision of its central rotation axis displacement by value f_common on section, which is symmetrically installed relative to shaft middle.

EFFECT: improved quality.

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Description

The invention relates to mechanical engineering, and more particularly to dressing with simultaneous finishing and hardening by surface plastic deformation of non-rigid shafts.

The prototype of the proposed method is a method of processing non-rigid shafts, in which preliminary elastic deformation of a non-rigid shaft and straightening with simultaneous surface plastic deformation are carried out with constant force of a deforming tool moving along a non-rigid shaft [1].

The disadvantages of this method are the lack of productivity and effectiveness of the correction of warpage of non-rigid shafts. The low productivity of dressing due to the high complexity of the process of preliminary elastic deformation of the shaft, carried out by applying bending moments. The insufficient efficiency of correcting the warping of the shafts is due to a correction error arising due to a change in the depth of penetration of the deforming tool due to the radial runout of the part during its planetary rotation around the line of centers.

The objective of the invention is to improve the quality of non-rigid shafts.

The technical solution of the proposed method is to increase the productivity and accuracy of editing non-rigid shafts with simultaneous hardening of their surface.

The technical solution is achieved due to the fact that the shaft before processing is elastically deformed by applying a transverse force from the concave side of the product in the direction of the deforming tool by an amount

where f _total - the value of the total elastic deformation of the shaft, measured from the line of centers, mm;

f _Ref is the value of the initial deflection of the shaft in the middle of the part, mm;

ζ is the bending coefficient, which is selected in the range of 0.01-5.0,

and dressing with simultaneous surface plastic deformation is carried out in each cross section of a non-rigid shaft rotating around its central axis, ensuring its displacement by the value of f _total in the area that is symmetrically located relative to the middle of the shaft.

This combination of new features with the known allows, in comparison with the prototype, to increase the productivity and accuracy of dressing of non-rigid shafts while strengthening their surface. Improving dressing productivity is achieved by simplifying the process of preliminary elastic deformation of the shaft. Improving the accuracy of editing non-rigid shafts is achieved by locking the elastically deformed shaft between the tops of the smoothing rollers and the deforming tool, which allows the shaft to rotate around its central axis and eliminates the negative effect of radial runout on the depth of tool penetration, which is inherent in the prototype.

Figure 1 presents a diagram of the process of preliminary elastic deformation of the shaft, carried out before processing; figure 2 shows the editing scheme with simultaneous finishing and hardening processing of non-rigid shafts; figure 3 is a section aa in figure 2.

The method is as follows.

A pre-rolling device with a deforming tool 8 in the form of a ball or roller is fixed in the tool holder, and the mechanism for pre-loading the workpiece 1, consisting of a screw pair 4, a carriage 5 and a support element made in the form of a prism 6 with two smoothing rollers 7, on the caliper lathe.

The initial deflection of the shaft 1 f _{Ref is} measured and the value of the bending of the shaft f _total calculated from the line of centers is calculated using the formula (1). The bending coefficient is selected in the range of 0.01-5.0. This range is proposed on the basis of a practical choice when dressing non-rigid shafts with surface plastic deformation. Beyond the lower limit, the method is ineffective, because the unevenness of the intensity of plastic deformation along the contour of the cross section of the shaft, which is necessary to eliminate warping, is not provided, and beyond the upper limit, the method is not feasible due to the occurrence of plastic deformation during bending of the shaft.

The machined shaft 1 is installed in the front 2 and rear 3 centers of the lathe in the convex position to the deforming tool 8. From the concave side of the shaft 1, a transverse force P _{y is} applied from the side of the support element by moving the carriage 5 by means of a screw pair 4 (Fig. 1). Thus, pre-elastic deformation of the shaft 1 is carried out by the value of f _total in the warpage plane of the product 1 in the direction of the deforming tool 8. In this position, the pre-loading mechanism of the workpiece 1 and the rolling device are moved along the forming part 1 to the beginning of the machined section of the shaft 1. To the part 1 summarize the deforming tool 8 and set the pressure in the hydraulic cylinder 9 (figure 2). In this case, the deforming tool 8 is pressed against the workpiece surface 1 with the magnitude of the working force P, which is selected from the conditions for the optimal plastic deformation. Turn on the drive rotation of the product 1, and the rolling device and the pre-loading mechanism of the workpiece 1 is informed of the longitudinal movement of the feed. Detail 1 during processing rotates around its central axis, offset from the line of centers 2, 3 in each cross section of the treated area by the value of f _total (figure 3).

Thus, an elastically deformed shaft is run-in in a section of length l (Fig. 2), which is symmetrically located relative to the middle of the part (L / 2), where L is the shaft length.

Achieving a positive effect of editing is explained by the following.

During rotation, the shaft 1 experiences alternating loading, which is caused by preliminary elastic deformation and warping of the part 1. When the initial concave side of the shaft 1 is rotated to the deforming tool 8, elastic tensile deformation always occurs in its surface layer, which is larger in magnitude than when the initial convex side is rotated. This deformation is combined with an elastoplastic deformation, which develops in the surface layer of the shaft 1 under the force action P of the deforming tool 8 in the process of surface hardening. In this case, the smoothing rollers 7, having the shape of a cylinder with a rectilinear generatrix, during processing do not carry out plastic deformation of the material of the surface layer of the part. As a result of the addition of deformations caused by the action P of the tool 8 and the transverse force P _y from the side of the support element, the surface layer along the contour of the cross section of the shaft receives different intensities of plastic deformation of the material. In this case, the surface layer from the concave side of the shaft receives a greater intensity of plastic deformation than from the convex side. The uneven distribution along the contour of the cross section of the shaft 1 of the intensity of plastic deformation of the material ensures its straightening. Thus, simultaneously with the rolling surface of the shaft 1 is the process of editing it strictly in the plane of warpage.

Example. According to the proposed method, a non-rigid shaft of steel 20 was processed with a radius of r = 7.5 mm and a length of L = 400 mm. The product had an initial deflection f _ref = 0.3 mm. Processing modes were assigned for which bending coefficient was determined from practical experience. So, when running the shaft with a deforming tool in the form of a ball with a diameter of 15 mm with a force of P = 1000 N, a longitudinal feed of S = 0.07 mm / rev and a rolling speed of v = 44 m / min, the bending coefficient was ζ = 2.0. By the formula (1), the total elastic bending deformation f _total = 0.9 mm was determined. The shaft was installed in the centers of the lathe and bent in the direction of the deforming ball by a value of f _total = 0.9 mm, counted from the line of centers. A section of the shaft with a length of l = 300 mm, which is symmetrically located relative to the middle of the shaft (L / 2), was processed in the indicated modes. After processing and unfastening the shaft, the value of the residual deflection was f _ost = 0.015 mm In addition, the running-in of the shaft made it possible to increase the surface hardness from HB 170 to HB 198 and reduce the roughness from R _a = 2.35 μm to R _a = 0.28 μm.

The use of the invention in comparison with the prototype allows you to more efficiently and effectively eliminate warpage of non-rigid shafts during the finishing and hardening of the surface treatment of products. This will reduce the number of defective products and reduce the cost of their manufacture.

Information sources

1. Patent 2021098 of the Russian Federation, B24B 39/04, B21D 3/16, 1994, BI No. 19 (prototype).

Claims (1)

A method of processing non-rigid shafts, including pre-elastic deformation of a non-rigid shaft, straightening with simultaneous surface plastic deformation, carried out with a constant force of a deforming tool moving along a generatrix of a non-rigid shaft rotating around its central axis, characterized in that the preliminary elastic deformation of the non-rigid shaft is carried out by applying transverse force from the concave side of the product in the direction of the deforming tool, by
f _total = (1 + ζ) f _out ,
where f _total - the value of the total elastic deformation of the shaft, measured from the line of centers, mm;
f _Ref is the value of the initial deflection of the shaft in the middle of the part, mm;
ζ is the bending coefficient, which is selected in the range of 0.01-5.0, and dressing with simultaneous surface plastic deformation is carried out in each cross section of the non-rigid shaft with the offset of its central axis of rotation by f _total in the area that is symmetrically located relative to the middle shaft.

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