RU2332290C1 - Method of burnishing spur gears - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention pertains to the technology of machine building and particularly to processing spur gears by surface plastic deformation. A deforming instrument is brought into intimate contact with the processed tooth gear. The deforming instrument is rotated while the processed tooth gear moves longitudinally back-and-forth and radially. The deforming instrument is in form of a hob with radial arms on its peripheral surface, on which wire rings, curved on the shape of the tooth, are rigidly fixed. The wire rings form a helical toothed ring. The arms are on the summits and depressions of the teeth of the helical toothed ring. In that case, there is crossing of the axes of the instrument and the work piece at an angle β=15°, which is equal to the angle of inclination of the teeth of the helical toothed ring.

EFFECT: increased efficiency and quality of processing tooth gears.

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Description

The invention relates to mechanical engineering technology, namely to the finishing of gears by surface plastic deformation.

Known final processing of the profile of the teeth, carried out without removing chips by plastic deformation of the metal in the cold state [1].

In the process of rolling, usually with two knurls made in the form of gears, a workpiece with pre-machined teeth located on parallel axes is run in. The rotating knurl, moving to the workpiece, when it reaches clearance-free engagement, starts the rolling process under a certain force. The distance between the axles of the knurl and the part is gradually reduced to obtain the required size of the teeth of the wheel.

During rolling, mutual sliding occurs on the teeth of the machined wheel and the knurl, which causes a metal shift on the sides of the teeth of the wheel.

The disadvantages of rolling with two knurls made in the form of gears are the limited possibilities in creating and managing heterogeneous hardened layers and regular microrelief of the treated surface, low efficiency, insufficiently deep hardened layer and insufficiently high degree of hardening of the treated surface - all this reduces productivity, accuracy and quality of the processing process.

The objective of the invention is to increase productivity and quality of processing by using elastic deforming elements that allow you to create and control the size of heterogeneous hardened layers and regular microrelief of the treated surface, characterized by high efficiency, providing a sufficiently large depth of the hardened layer and a high degree of hardening of the processed surface due to the crossing axes of the proposed tool and the gear being machined and sliding deforming elements along the tooth agotovki.

The problem is achieved by using the method of rolling in spur gears, including introducing into the clearance-free gearing with the work gear the deforming tool for performing an interference fit, communicating rotational movement to the work tool and reciprocating longitudinal and radial movement of the work gear, using a deforming tool in in the form of a hub with racks radially located on its peripheral surface on a cat bent wire rings made from the conditions for the formation of a helical gear rim are rigidly fixed, the racks are located at the vertices and depressions of the teeth of the helical gear, while the axes of the tool and the workpiece are crossed at an angle β = 15 °, which is equal to the angle of inclination of the teeth a helical gear, and the parameters of the teeth of the helical gear having a profile angle α _t , deg, modulus m _t , mm, pitch diameter d ₀ , mm, main circle diameter d _bo , mm, the tooth thickness in an arc divides of a solid circle in the end section S _t0 , mm, is taken equal to: tan α _t = tan α / cos β; m _t = m / cos β; d _o = m _t z; d _bo = d _o cos α _t ; S _to = π m _t / 2 + 2h; where α = 20 ° is the profile angle of the producing rail; m is the module of the gear being machined, mm; h - interference, mm.

In Fig.1 shows a diagram of the helical rolling of the proposed deforming tool spur gear; figure 2 is a view of the tool from the right end in figure 1; figure 3 is a top view of a figure 2; figure 4 - section B - B in figure 3; figure 5 - deforming element is a wire ring, curved in the shape of the ring gear; figure 6 is a variant of the deforming element in the form of a tooth, curved in the shape of the latter; in Fig.7 is a view of the tool from the right end in Fig.1, the working part of which is assembled from individual deforming elements shown in Fig.6; in Fig.8 is an option for mounting deforming elements on racks, section B - B in Fig.3; figure 9 is an element of the gearing of the tool with the machined wheel, to determine the magnitude of the interference fit h.

The proposed method is intended for the finish machining of the teeth of spur gears of external gearing. The final processing of the tooth profile is carried out without removing chips by plastic deformation of the metal in the cold state.

The tool that implements the method is made in the form of a gear wheel and is equipped with a hub 1 with racks radially located on the peripheral surface at the places of the tops and troughs of the teeth, while at the places of the tops of the teeth there are higher struts 2 than the racks 3 in the places of the troughs.

On the outer surface of the uprights 2 and 3 are formed grooves in which are rigidly fixed wire ring 4, the curved shape of the tooth and form a ring gear required width _VI.

Figure 5 conventionally shows three teeth of a gear wire ring 4.

Number toothed wire rings 4 depends from the tool _U and the width B in the processed wheel _W, the wire diameter and the design features of fastening and sealing rings on the racks.

Figures 4 and 8 show two options for mounting rings on racks in which the grooves are made: embossed and a tightening bolt 5, respectively. For large-modular wheels, a tool with deforming elements in the form of a tooth 6 is used (see Fig. 6) with their fastening in grooves using clamping strips 7 and bolts 8 (see Fig.7).

When processing spur gears, the angle of inclination of the teeth of the tool is β = 15 ° the angle of intersection of the axes of the tool and the workpiece, and the profile angle α _t , module m _t , mm, pitch diameter d _o , mm, diameter of the main circle d _bo , mm, thickness the tooth along the arc of the pitch circle S _to , mm, in the end section are determined by the formulas:

tan α _t = tan α / cos β; m _t = m / cos β, mm; d _o = m _t z, mm; d _bo = d _o cos α _t , mm;

S _to = π m _t / 2 + 2h, mm,

where α = 20 ° is the profile angle of the producing rail;

m is the module of the gear being machined;

S _o - the thickness of the tooth along the arc of the pitch circle in the end section;

h - interference.

In the process of processing the proposed method using a deforming tool, which is made in the form of a gear wheel, run in the workpiece with pre-machined teeth, while the axes of the tool and the workpiece are crossed straight. A rotating tool, moving to a workpiece with a radial feed S _P , when reaching clearance-free engagement, the rolling process begins under a certain force. The distance between the axes of the tool and the workpiece is gradually reduced to obtain the required size of the teeth of the wheel. During the running-in on the teeth of the machined wheel and the tool, there is mutual sliding, which causes a metal shift on the sides of the teeth of the wheel.

The main technological parameter of the process is interference h (see Fig. 9), created due to the radial feed S _P. Processing is carried out with an interference fit h = 0.5 ... 1.5 mm. The tightness is limited by the ductility of the material of the part. When processing with small tightness, shape deviations are reduced, dimensional accuracy is increased, and surface roughness parameters are also reduced. With small interference, workpieces are also treated after heat treatment.

During processing, the tool and the workpiece are introduced into the buzz gap engagement. The tool is driven in rotation with a frequency of V _AND and drives the gear being machined, mounted on a mandrel freely mounted in the centers.

Contact points observed at different points in time form a line on the tooth surface running on the side surface from the bottom of the cavity to the top of the tooth. This contact line will be processed by the tool with a constant relative position of the axes of the tool and the gear. Therefore, in order to process the completely lateral surface of the teeth, the reciprocating wheel is informed of the reciprocating movement S _pr along its axis.

After each double wheel stroke, there is a radial feed S _P , i.e. the axes of the tool and the workpiece come together until the thickness of the teeth of the machined wheel is equal to the required.

Example. A spur gear (z = 32: m = 4 mm) was rolled from steel 45 on a horizontal gear-shaving machine mod. 5702 In the present method flow forming tool: helical, crossing angle of axes of tool and workpiece β = 15 °, the diameter of the arbor hole of 63.5 mm, _and the width B = 50 mm, the nominal pitch diameter of 240 mm, the number of teeth of the tool 58.

The fixed force action is 400 ... 800 N. The hardness of the workpiece material is 32 ... 36 HRC. The deforming ring spring was made of an alloy of 38KhMYuA grade and after nitriding had a hardness of 60 ... 64 HRC. Then its surface was polished to Ra = 0.04 ... 0.08 μm.

Compared to shaving, rolling around with the rolling tool of the proposed method made it possible to increase productivity by 4.5 times, reduce the surface roughness parameter on the tooth profiles to Ra = 0.32 μm, reduce the sound pressure level by 3 ... 4 dB, increase the stability of gear mesh sizes and quality. The tool life was 300 thousand parts, the wheel break-in time was 24 s. During heat treatment, the teeth of the run-in wheels, due to the more uniform structure of the surface layers, were deformed less than the sheaved ones. The accuracy of the gears before running in should be higher, and the allowance on the side of the tooth is less than half before shewing.

During processing, industrial oil 20 was used as a cutting fluid.

The proposed method, carried out by a spring tool, has practical utility, is technologically advanced, relatively simple and cheap to manufacture, easy to maintain, expands technological capabilities and provides high efficiency of finishing and hardening processing of spur gears of both external and internal gearing.

The proposed method improves the productivity and quality of processing by using elastic deforming elements that allow you to create and control the size of heterogeneous hardened layers and regular microrelief of the treated surface, characterized by high efficiency, provides a sufficiently large depth of the hardened layer and a high degree of hardening of the treated surface due to the intersecting axes of the tool and the machined gear wheel and sliding deforming elements along the tooth of the workpiece.

Information sources

1. Reference technologist-machine builder. In 2 vols. T.1 / Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering, 1986. S.352-353 - prototype.

Claims (1)

A method of rolling in spur gears, including introducing into the clearance-free gearing with a workable gear wheel a deforming tool for performing an interference fit, communicating rotational movement to the deforming tool and reciprocating longitudinal and radial movement of the workable gear wheel, characterized in that they use a deforming tool in the form of a hub with racks radially located on its peripheral surface, on which curved about the shape of the tooth, wire rings made from the conditions for the formation of a helical gear, the racks are located at the tops and valleys of the teeth of the helical gear, while the axes of the tool and the work are crossed at an angle β = 15 °, which is equal to the angle of inclination of the teeth of the helical gear, and the parameters of the teeth of the helical gear teeth having the profile angle α _t , deg, modulus m _t , mm, the diameter of the pitch circle d _o , mm, the diameter of the main circle d _bo , mm, the thickness of the tooth along the arc of the pitch circle in the end section nii S _to , mm, take equal to: tgα _t = tgα / cosβ; m _t = m / cosβ; d _bo = d _o cosα _t ; S _to = πm _t / 2 + 2h, where α = 20 ° is the profile angle of the producing rail; m is the module of the gear being machined, mm; h - interference, mm.

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