GB2041805A - Tool for Working Holes by Plastic Deformation - Google Patents

Abstract

A tool for smoothing holes by rolling comprises a head (1) having deforming elements with working surfaces which lie on an imaginary sphere, the head being mounted on a holder (5) for rotation about an axis inclined to the longitudinal axis about which the tool is rotated. The deforming elements (7) may be integral with the head (1) or mounted on it rigidly or resiliently. The head may comprise a stack of independently rotatable discs and is preferably capable of limited radial movement. <IMAGE>

Description

SPECIFICATION Tool for Working Holes by Plastic Deformation The present invention relates to tools for working holes and, more particularly, it relates to tools for working holes by plastic deformation.

This invention can be utilized most advantageously for finishing deep (1/do10) holes and for working holes with the required surface roughness of Ra < 0.1 6-1 .25jot.

According to the invention there is provided a tool for machining holes in workpieces by plastic deformation, comprising a holder having an axis about which the holder is rotated relative to the workpiece in use of the tool and a head mounted on the holder for rotation about an axis inclined with respect to the holder axis, the head including deforming elements with working surfaces which lie on an imaginary sphere.

In the course of working a hole, the summation of the rotary motions of the workpiece and of the head, when the head is rotatable about an axis inclined at an angle t to the holder axis, results in a rocking motion of the deforming elements relative to the hole being worked with a rocking angle of 2a. Thanks to said rocking motion, the working portions of the deforming elements are continuous!y replaced and the wear of the deforming elements is reduced by a factor equal to the number of lengths of the working portions fitted into the length of each deforming element within a spherical band with a central angle equal to 2a The arrangement of the working surfaces of deforming elements on an imaginary sphere provides for the maximum length of each deforming element which, in turn, ensures their minimum wear.

The head makes it possible to combine the working of holes by rolling with simultaneous smoothing of their surfaces.

The deforming elements may comprise projections on the surface of the head.

The provision of projections on the head surface serves to reduce the area of contact of the head with the hole surface and increase contact stresses in the course of working, which allows simultaneous rolling and smoothing with the minimum work and power consumption.

The projections can be located in plane sections of the head to simplify the tool manufacture, and they can be arranged at an angle to axial sections of the head so that the hole under treatment can be worked over the entire perimeter or part thereof, depending on the selected angle of the projections, rotation of the head as a result of interaction with the hole being worked, which obviates the need for a special head rotation drive. In so doing, the tool capabilities are extended since, for example, faceted holes can be worked.

The projections can be arranged to extend along a spiral so that the elements have increased length and reduced wear. In addition conditions of the tool operation are improved and, in particular, its entry into the hole being worked becomes smoother.

When working precision holes, it is expedient that the deforming elements should be rigidly connected with the head in order to simplify the tool design. This also allows the calibration of holes.

When working holes with relatively large tolerances on the order of tenths of a millimeter and more, it is expedient that the deforming elements should be resiliently connected to the head.

With a view to simplifying the tool design and improving its efficiency when working small diameter holes, it is expedient that the deforming elements be constituted by an annular surface portion of the head itself which is coincident with the imaginary sphere.

It is possible for the head to be made up of a set of disks mounted on the holder with a possibility of rotating independently of each other.

This helps ensure, in the course of the tool operation, the optimum speed of rotation of each one of the disks as a result of interaction with the hole being worked, and improved working conditions, as well as reduced wear of the deforming elements owing to the reduction of the working sliding speeds.

In order to provide for self-setting of the tool relative to the hole in the course of working the latter, the head can be mounted on the holder with a possibility of moving in a radial direction relative to the holder axis.

The present invention will be made apparent upon considering the following detailed description of an exemplary embodiment thereof, with due reference to the accompanying drawings in which: Figure 1 is a general axonometric view of the tool for working holes, according to the invention, with deforming elements in the form of projections on the head; Figure 2 is a general view of the tool of the invention, wherein a surface fashioned as a smooth spherical belt is used as a deforming element; Figure 3 is a general view of the tool of the invention, on whose head projections are arranged on a spiral; Figure 4 is a diagrammatic cross-sectional view of the head of the tool according to the invention, featuring the various versions of deforming elements; and Figure 5 is a longitudinal sectional view of the tool of the invention, wherein the head is made up of a set of disks.

Disclosure is made of a tool for working holes by plastic deformation, comprising a head 1 (Fig.

1 ) carrying deforming elements.

The head 1 has a body 2 made as a body of revolution with a central opening 3 (Fig. 2) for mounting it in a journal 4 of a holder 5.

By means of the holder 5 the tool is secured in a spindle (not shown in the drawing), tailstock spindle or in some other device designed for the purpose.

According to the invention, the head 1 is mounted in the journal 4 of the holder 5 for rotation about axis 0--0 inclined with respect to axis L-L of the holder 5 at an angle cr. Rotation is made possible by the provision of bearings 6 (Fig.

1).

The head 1 carries deforming elements whose working surfaces lie in an imaginary sphere shown with dot-and-dash line in Figs. 1, 2, 3.

The deforming elements are made as projections 7 (Fig. 1) on the surface of the head, which serve to reduce the area of contact of the head with the surface of hole 8 being worked and increase contact stresses in the course of working.

As shown in Fig. 3, the projections 7 are arranged at an angle p of up to 900 to axial sections of the head 1, in particular, those coinciding with the plane of the drawing in Fig. 3.

For simplifying the head design, the projections 7 are located in plane sections thereof, as shown in Fig. 1.

With a view to increasing the working length of the deforming elements, in Fig. 3 are shown projections 7 arranged on a spiral.

For simplifying the tool design, the deforming elements are rigidly connected with the head 1.

Such elements can be provided by projections 7a (Fig. 4) made integral with the body 2 of the head 1, or detachable projections 7b, as well as by projections 7c in the form of rolling bodies mounted for movement in races provided in the body 2 of the head 1.

When working holes with large tolerances, the deforming elements in the form of projections 7d are resiliently connected with the head 1 through the intermediary of, say, a spring 9.

When working smail-diameter (up to 50 mm) holes or holes in parts made of soft materials, a surface 10 of the head 1 (Fig. 2) fashioned as a smooth spherical belt is used as the deforming element.

The tool head 1 shown in Fig. 5 is made up of a set of disks 1 1 having a rounded profile to provide for the smoothing of holes being worked. The disks 11 are mounted on the holder 5 with a possibility of rotating independently of each other.

This helps ensure, in the course of operation, the minimum sliding speeds of the deforming elements relative to the hole 8 being worked, thereby reducing the wear of the deforming elements.

Fig. 2 shows the head 1 mounted on the holder 5 with a possibility of moving in a radial direction relative to the axis of the holder 5. To this end, the head 1 is mounted on the holder 5 with a gap 12 provided over the central opening 3 of the body 2.

The possibility of radial movement can also be provided through the use of floating tool heads of any design known to those skilled in the art.

The possibility of radial movement facilitates considerably the tool adjustment.

The tool of the present invention operates in the following manner.

The tool holder 5 is secured with its shank or flange in the faceplate, spindle, tailstock or support of the machine coaxially with the hole 8 being worked of a blank mounted on the machine spindle support or table. The machine drive motor imparts rotation to the blank and/or tool about a common axis L-L, together with longitudinal feed movement (in the direction of arrow). The tool is introduced in the blank hole 8 being worked in which the tool head 1 is self-set owing to the provision of the gap 12 of the central opening 3 or thanks to radial movement (floating) of the head 1 relative to the axis L-L of the holder 5.The blank sets the head 1 to rotation in the journal 4 whose axis 0--0 is arranged at an acute angle a to the axis L-L of the holder 5, with the portions deforming elements of the head 1 in contact with the blank hole 8 being worked at each moment of time alternating continuously within the limits of the surface of an imaginary spherical band ABCD (Fig. 2) thanks to their rocking motion relative to the surface of the hole 8 through an angle of 2a. Thus, in the position shown in Fig. 2, the portions of deforming elements of the head 1 having a length I, and adjoining points B and C are operative, while a turn of the head 1 through 1800 about the axis 0--0 makes operative the portions adjoining points A and D, and so on.In so doing, the wear of the deforming elements of the tool is reduced, as compared with the prototype, by a factor at least equal to the number of working portions of the length I, fitted into the length of arc AB and CD of each deforming element within the spherical band ABCD of the head 1. This continuous alternation of the working portions of the deforming elements further results in a considerable temperature decrease in the working zone owing to short duration of contact of the deforming elements with the blank hole 8 befngworked and subsequent prolonged cooling. All this makes for an improved efficiency, accuracy and quality of working.

The provision of projections makes for the concentration of deformation stresses in the zone of contact with the hole being worked, which results in a considerable reduction of the force of working and power consumed in the course of working. In addition, the provision of projections presumes the presence of recesses therebetween which, in turn, makes for a free flow of the blank material in the course of its being deformed by the projections. The free flow of material improves the conditions of plastic deformation and, consequently, makes for improved quality and accuracy of working.

The proper choice of the angle of inclination of the projections to axial sections of the head provides for the possibility of working the hole under treatment over the entire perimeter or part thereof and, consequently, for extended capabilities of the tool.

The wear of the deforming elements can be further reduced through the use of the head 1 made up of a set of disks mounted on the holder with a possibility of rotating independently of each other. In so doing, the disks rotated by the blank independently of each other attain the mode of the minimum sliding speed between the deforming elements and the hole.

Claims (10)

Claims

1. A tool for machining holes in workpieces by plastic deformation, comprising a holder having an axis about which the holder is rotated relative to the workpiece in use of the tool, and a head mounted on the holder for rotation about an axis inclined with respect to the holder axis, the head including deforming elements with working surfaces which lie on an imaginary sphere.

2. A tool as set forth in claim 1, wherein the deforming elements comprise projections on the head.

3. A tool as set forth in claim 2, wherein the projections are inclined to the axial plane of the head.

4. A tool as set forth in claim 2 or 3, wherein the projections lie in planar sections of the head.

5. A tool as set forth in claim 4, wherein the projections are arranged to extend along a spiral path.

6. A tool as set forth in any one of claims 1 to 5, wherein the deforming elements are rigidly connected to the head.

7. A tool as set forth in any one of claims 1 to 5, wherein the deforming elements are resiliently connected to the head.

8. A tool as set forth in claim 1, wherein the deforming elements are formed by a portion of the head having an annular surface coincident with the imaginary sphere.

9. A tool as set forth in claim 1, wherein the head comprises a set of disks mounted on the holder for rotation about the inclined axis independently of each other.

10. A tool as set forth in any one of the preceding claims, wherein the head is capable of limited movement relative to the holder radially of the inclined axis.

1 A tool for machining holes by plastic deformation, substantially as herein described with reference to the accompanying drawings.