GB2152416A

GB2152416A - Broaching machine tool

Info

Publication number: GB2152416A
Application number: GB08400708A
Authority: GB
Inventors: Alan Bryson Riach; Daniel Whitelaw Wright
Original assignee: FLEMING THERMODYNAMICS Ltd
Current assignee: FLEMING THERMODYNAMICS Ltd
Priority date: 1984-01-12
Filing date: 1984-01-12
Publication date: 1985-08-07
Also published as: WO1985003020A1; GB8400708D0; EP0168457A1

Abstract

A broaching machine tool has a tool (11) which can be rotated in a controlled manner whilst a non-rotating workpiece (10) is moved past its cutting edges. After passing through the tool the workpiece will have had a profile not parallel to the direction in which it was broached. Accurate electronic means (16/17, 18/19, 20) are provided for controlling the ratio of linear to rotational movement.

Description

SPECIFICATION Rotational profile broaching machine tool This invention relates to a rotational broaching machine tool.

Broaching machine tools are well known machines comprising a means by which a profile or profiles can be formed in a workpiece by forcing a shaped tool past or through the workpiece or inversely by passing the workpiece past a stationary tool in a linear manner. The shaped tool has a cutting edge or edges formed on it which cuts an inverted replica of its own shape in the workpiece.

Broaches are usually limited to cutting in a plane parallel to the direction in which the broach tool travels limiting their use to producing shapes of straight or linear form.

Broaches have been made to produce helical shapes. However the shape has been controlled simply by either producing helical tool forms or by controlling the relevant motions with a mechanical cam.

Typical examples of shapes formed by the currently known broaching process are shown in Figure I together with a diagrammatic representation of a broaching machine.

According to the present invention there is provided a rotational broaching machine tool comprising a frame containing a device for holding a workpiece, a tool holder and means of rotating and moving linearly one relative to the other in a predetermined and controlled manner using positional transducers giving an electronic and/or optical signal, electronic or optical signal processing and electronic control and actuation.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 2 shows in perspective the machine tool with a workpiece and cutting tool in place.

Figure 3 illustrates the cutting principle.

Figure 4 shows the means of control of the rotational movement of the tool in relation to the workpiece.

Referring to the drawing, the rotational broaching machine tool comprises a frame 9 into which is built a non-rotating actuating ram 14, a rotational tool holder 13 and a motive means 15 by which the tool holder 13 can be made to rotate on bearing 21.

The workpiece 10 is rigidly attached to the nonrotating actuation ram 14. The cutting tool 11 with cutting edges 12 is rigidly attached to the rotational tool holder 13.

In order to machine the workpiece 10, onto which in this case it is desired to form helical lobes, the actuation ram 14 is forced down by oil pressure or other means whilst the tool holder 13 is rotated in a predetermined way by the motor 15.

As the non-rotating workplace 10 is moved through the rotating cutting tool 11 a profile is cut on the workpiece of a non-iinear form. The exact curvature of inclination of the profile may be varied by varying the ratio of angular velocity of the tool to linear velocity of the workpiece.

This ratio can be conveniently predetermined and controlled by integrating the signals from angular measuring devices 16 & 17 and linear measuring devices 18 & 19. This integration can be achieved by means of a microprocessor 20, the signal from which can be used to actuate and control motor 15.

1. A rotational broaching machine tool comprising a frame containing a device for holding a workpiece, a tool holder and means of rotating and moving linearly one relative to the other, in a predetermined and controlled manner, using positional transducers giving an electronic andíor optical signal, electronic or optical signal processing and electronic control and actuation.

2. A rotational broaching machine tool as claimed in Claim i wherein the linearly moving member is moved by means of a motive device.

3. A rotational broaching machine tool as claimed in Claim 1 or Claim 2 wherein the rotating member is rotated by means of a motive device.

4. A rotational broaching machine tool as claimed in Claim 3 wherein the ratio of the linear to the rotational movement is varied by controlling the motive device driving the rotating member.

5. A rotational broaching machine tool as claimed in Claim 4 wherein the motive device is controlled by the signal from an electronic processor.

6. A rotational broaching machine tool as claimed in Claim 5 wherein the electronic processor derives signals defining the relative positions of the moving parts from linear and rotational position measuring transducers mounted on the parts travelling in a linear and rotational manner respectively.

7. A rotational broaching machine tool as claimed in Claims 1-6 wherein the actuation ram moves linearly, is non-rotating and holds the work piece and the tool holder is r rotated, S. A rotational broaching machine tool as claimed in Claims 1-6 wherein the tool holder is stationary and the actuation ram moves linearly and rotates and holds the workpiece.

9. A rotational broaching machine tool as claimed in Claims 1-6 wherein the actuation ram moves linearly, is non-rotating and holds the cutting tool, and wherein the workpiece is mounted in a rotating holder.

10. A rotational broaching machine tool as claimed in Claims 1-6 wherein the actuation ram moves linearly and rotates and holds the cutting tool and wherein the workpiece is stationary and fixed rigidly to the frame.

11. A rotational broaching machine tool substantially as described herein with reference to Figures 2-4 of the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Rotational profile broaching machine tool This invention relates to a rotational broaching machine tool. Broaching machine tools are well known machines comprising a means by which a profile or profiles can be formed in a workpiece by forcing a shaped tool past or through the workpiece or inversely by passing the workpiece past a stationary tool in a linear manner. The shaped tool has a cutting edge or edges formed on it which cuts an inverted replica of its own shape in the workpiece. Broaches are usually limited to cutting in a plane parallel to the direction in which the broach tool travels limiting their use to producing shapes of straight or linear form. Broaches have been made to produce helical shapes. However the shape has been controlled simply by either producing helical tool forms or by controlling the relevant motions with a mechanical cam. Typical examples of shapes formed by the currently known broaching process are shown in Figure I together with a diagrammatic representation of a broaching machine. According to the present invention there is provided a rotational broaching machine tool comprising a frame containing a device for holding a workpiece, a tool holder and means of rotating and moving linearly one relative to the other in a predetermined and controlled manner using positional transducers giving an electronic and/or optical signal, electronic or optical signal processing and electronic control and actuation. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 2 shows in perspective the machine tool with a workpiece and cutting tool in place. Figure 3 illustrates the cutting principle. Figure 4 shows the means of control of the rotational movement of the tool in relation to the workpiece. Referring to the drawing, the rotational broaching machine tool comprises a frame 9 into which is built a non-rotating actuating ram 14, a rotational tool holder 13 and a motive means 15 by which the tool holder 13 can be made to rotate on bearing 21. The workpiece 10 is rigidly attached to the nonrotating actuation ram 14. The cutting tool 11 with cutting edges 12 is rigidly attached to the rotational tool holder 13. In order to machine the workpiece 10, onto which in this case it is desired to form helical lobes, the actuation ram 14 is forced down by oil pressure or other means whilst the tool holder 13 is rotated in a predetermined way by the motor 15. As the non-rotating workplace 10 is moved through the rotating cutting tool 11 a profile is cut on the workpiece of a non-iinear form. The exact curvature of inclination of the profile may be varied by varying the ratio of angular velocity of the tool to linear velocity of the workpiece. This ratio can be conveniently predetermined and controlled by integrating the signals from angular measuring devices 16 & 17 and linear measuring devices 18 & 19. This integration can be achieved by means of a microprocessor 20, the signal from which can be used to actuate and control motor 15. CLAIMS

7. A rotational broaching machine tool as claimed in Claims 1-6 wherein the actuation ram moves linearly, is non-rotating and holds the work piece and the tool holder is r rotated,

S. A rotational broaching machine tool as claimed in Claims 1-6 wherein the tool holder is stationary and the actuation ram moves linearly and rotates and holds the workpiece.