RU2393038C1 - Method to produce tubes with end bulges - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to metal forming, particularly to production of sleeves with collars from tubular workpieces. Tubular workpiece is fitted inside circular mandrel, thrust against bearing bush and deformed by multistage tool from inside, said tool having toroidal working sections. Said tool is moved along workpiece axis towards bulge being formed, while bearing bust is thrust against workpiece face on the side of aforesaid bulge. ^ EFFECT: formed bulge diametre increases due to using metal pressed by tool out all along workpiece length. ^ 2 dwg

Description

The invention relates to methods for the manufacture of sleeves with a shoulder from a tubular workpiece.

A known method of planting the end thickenings on the pipes [1], in which the pipe is mounted on the mandrel and the end thickenings are planted by applying forces along the axis of the pipe, and oppositely directed support forces to the pipe end.

The disadvantage of this method is that it does not provide a transition of a given shape from a thickening to the pipe wall.

A known method of manufacturing bushings with an end thickening from a tubular billet [2], which is mounted on an annular mandrel and deform from the inside with a multi-stage tool, exerting forces directed along its axis, and oppositely directed support forces are applied to one of the ends of the billet. In this case, the workpiece is set so that its end face protrudes above the annular mandrel by an amount equal to the height of the thickening formed, the working sections of the tool are used in a conical shape, and the tool is moved from the protruding end to the opposite during processing.

The disadvantage of this method is the low value of the formed thickening, which is limited by the total amount of interference between the annular mandrel, the workpiece and the tool in the area of the protruding part of the workpiece. The metal extruded by the tool along the rest of the workpiece moves to the free end and therefore is used not to form a thickening, but to elongate the workpiece.

The task of the invention is to increase the possible diameter of the formed thickening due to the use of metal extruded by the tool along the entire length of the workpiece.

The problem is solved in that in the method of manufacturing bushings with an end thickening from a tubular billet, which is installed inside an annular mandrel, abut against a support sleeve and deform from the inside with a multi-stage tool, applying forces directed along its axis, the working sections of the tool use a torus shape, the tool in the processing process is moved along the axis of the workpiece in the direction of the formed thickening, and the support sleeve rests on the end face of the workpiece from the side of the formed thickening.

Since the tool during processing is moved towards the formed thickening, the metal extruded by the mandrel along the entire length of the workpiece is moved towards the formed thickening and used to form it. Due to this, the possible diameter of the formed thickening is significantly increased. The working sections of the tool are made in a toroidal shape, as this reduces the radial load in the metal deformation zone and limits the possibility of elongation of the workpiece, which also contributes to an increase in the diameter of the end thickening. The support sleeve is installed on the side of the formed thickening, as this allows you to direct the metal moved by the tool into the zone of formation of the end thickening and to form the end thickening of the required height.

The essence of the invention is illustrated by drawings, where figure 1 shows a diagram of the formation of the end thickening, and figure 2 is a diagram of the formation of a thickening in the middle of the sleeve.

The tubular billet 1 (Fig. 1) is installed in an annular mandrel 2, mounted on a support sleeve 3 based on a cylindrical centering belt. The support sleeve 3 is mounted on the stand 4. The workpiece 1 initially has a cylindrical shape (not shown). A cylindrical groove is made in the lower part of the annular mandrel 2, which, together with the cylindrical centering belt of the support sleeve 3, forms a cavity 5 intended for forming an end thickening on the blank 1. From the upper part of the workpiece 1, an ejector 6 is installed in the annular mandrel 2, which also limits the possible elongation of the workpiece 1 during processing.

A two-stage tool 7 having toroidal working sections with diameters dl and d2 and a peripheral radius r is installed in the opening of the workpiece 1 from the side opposite to the end thickening being formed. The diameter of the last stage is taken equal to the diameter of the obtained hole parts

and the diameter of the previous steps is less than the diameter of the next step by the required amount of interference. In this case:

where dν is the required hole diameter of the resulting part;

Δ2 - the required interference between the workpiece 1 and the second working stage of the tool 7.

The peripheral radius of the profile of the working sections of the tool r for workpieces of small diameter is usually used more than half the diameter of the hole of the workpiece, for workpieces of large diameter the peripheral radius r can be more than half the diameter of the hole of the workpiece. In practice, more often the peripheral radius of the tool r is taken equal to half of the formed diameter of the billet hole so that the working sections of the tool have the shape of spheres.

An axial load P is applied to the upper part of the two-stage tool 7, under the action of which the tool 7 is tightly moved along the axis of the workpiece 1. At the same time, the metal extruded from the surface of the workpiece opening moves the working sections of the tool toward the thickening formed and when the tool reaches a cylindrical groove 5 of the annular mandrel 2 the extruded metal fills the cylindrical groove 5. An end thickening of the workpiece is thereby formed.

Example. It is required to make the inner ring of the roller bearing 42205 with an outer diameter dd = 31.7 mm, an inner diameter dν = 24.75 mm, a height hd = 15.2, and at the end of the part, form a shoulder with a height of hb = 3.35 mm and a diameter of db = 34 , 6 mm. We take a tubular billet 1 with an outer diameter of Dz = 31.5 mm and a height of hz = 15.2 mm. The diameter of the annular mandrel 2 D = 31.7 mm At the end of the annular mandrel 2 a cylindrical groove with a diameter of 35.2 mm and a length of 7 mm is made. A cylindrical centering belt 3.65 mm high is made on the support sleeve 3. Thus, when installing the annular mandrel 2 on the supporting sleeve 3, they form a cavity 5 with a diameter of dp = 35.2 mm and a height of hp = 3.35 mm.

The outer diameter of the ejector 6 is 31.65 mm, and the inner is equal to the diameter of the hole of the received part 24.75 mm. As a tool, we use a cylindrical mandrel with a diameter of 24.70 mm. The tool has two working steps. The diameter of the second stage according to (1) is taken equal to the required diameter of the billet hole d2 = 24.75 mm.

From the conditions of the need for the formation of the required collar volume, we determine the inner diameter of the workpiece:

where k _c is a coefficient that takes into account the loss of metal when cutting a burr at the exit of the tool from the workpiece.

Substituting the known parameter values into equality (3), we determine:

Preloads for the first Δ1 and second Δ2 steps are assumed to be the same. Then

where Δ is the total required amount of interference required to form the end thickening.

From (4) we determine:

The peripheral radius r of the torus surfaces of the working parts of the mandrel, on the one hand, should have a value that prevents the possibility of elongation of the workpiece during processing, and, on the other hand, a value that prevents the possibility of cutting the metal. The first value of the radius is determined from the relation:

From equality (5) we determine:

The second value is determined from the condition:

where k is a coefficient varying from 2 to 5 depending on the degree of lubrication of the contacting surfaces of the tool and the surface to be treated. From equality (6) we find:

We accept r = 6 mm.

When treating the surface with a tool with a conical working part, an excessively large contact strip appears, which leads to the loss of a significant part of the deformable metal to elongate the workpiece.

Various embodiments of the method are possible. For example, instead of a solid tool in the form of a mandrel, balls with successively increasing diameters can be pushed alternately into the billet hole. The thickening of the workpiece by the proposed method can be carried out not only on the extreme surface, but also in the middle of the workpiece. To do this, it is necessary to process the surface of the workpiece by the proposed method alternately from two sides, directing the metal on both sides to the place of thickening of the workpiece.

Technical and economic effectiveness of the proposed method is as follows.

1. The ability to form thickenings of larger diameter.

2. The possibility of increasing the accuracy of the machined part by preventing the elongation of the workpiece during processing.

Information sources

1. The method of planting thickenings mainly conical shape on the pipe blanks and a stamp for its implementation. A.S. No. 1502153 A1, B21j 5/08.

2. A method of manufacturing bushings with end thickening. A.S. No. 295591, B21d 22/06.

Claims (1)

A method of manufacturing bushings with an end thickening from a tubular workpiece, comprising installing a tubular workpiece inside an annular mandrel with abutting its end face in the support sleeve and deforming the tubular workpiece from the inside with a multistage tool by applying forces directed along its axis, characterized in that they use a multistage tool with torus working sections forms, and during deformation it is moved along the axis of the workpiece in the direction of the resulting end thickening, while the supporting sleeve is abutted against the end face Preparations formed by thickening.

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