GB2268109A - Machine tool cutter head - Google Patents

Abstract

The machine tool for mounting a laser or plasma cutter head (10) comprises a member (12) for connecting the head (10) thereto via a connecting piece (14). This piece (14) terminates in a portion (16) that can be gripped by the jaws of a machine tool robot arm (not shown). The cutter (10) is mounted on the member (12) for movement in linear directions, laterally of the axis of rotation of the member, the movement is actuated by an electric motor (18), a drive shaft (20) to a motor driver gear (22). This enables fine positioning of the cutter head (10) with respect to a workpiece without the necessity for moving the robot arm. It further enables complicated two dimensional forms to be cut without necessarily moving the robot arm. <IMAGE>

Description

MACHINE TOOL CUTTER HEAD The present invention relates to a cutter head of the kind which supports a cutter which can be moved with and relative to the head and a machine tool on which the head is mounted for use.

The invention has particular efficacy when used to support a cutter of the kind which melts and/or vaporises metal, as opposed to removing metal by paring.

Thus it is eminently suitable for use with plasma and laser cutters.

Modern machine tools have greater -flexibility in the machining of metals than ever before. Such flexibility has proved necessary, to enable rore rapid mass production of objects for markets such as the motor car industry, whilst maintaining accuracy of the machining process.

An example of flexibility is in the forming of holes in sheet metal components. Where previously, holes were produced by stamping or punching with dies preshaped to the desired hole profile, those holes are now produced by trepanning with laser or plasma cutters.

It is known to employ robot machines, ie computer operated machines which have articulated arms. The free end of the arm carries a cutter head, which has a cutter mounted therein.

Most such machines are restricted to moving the cutter head and cutter together, there being no facility for achieving relative positioning of head and cutter.

It is known however, to position a cutter coaxially of the head and, using the axis of the head as a datum, offset the cutter therefrom. On rotating the head about its axis, the cutter trepans a circular disc from a workpiece, the radius of the circle being equal to the offset distance, plus a half beam thickness. Further, the machine tool is capable of trepanning more complex shapes, eg elliptical and rectangular, the latter having individual radiussed corners.

A particular construction of this latter machine tool is described and claimed in US patent specification 4,884,189. That construction comprises a plethora of shafts and gear connections.

The present invention seeks to provide a much simplified construction, without loss of efficiency.

According to the present invention a machine tool cutter head comprises a member rotatably connectable to a machine tool and including a cutter which cuts with energy derived from light or a gas and which is mounted on said member for movement bodily relative thereto in linear directions laterally of the axis of rotation of said member, said movement being effected by linearly movable force applying means which are connected to a pair of motor driven gears for activation.

The invention will now be described, by way of example and with reference to the accompanying drawings in which: Fig 1 is a part cross sectional view of a machine tool cutter head in accordance with one embodiment of the present invention.

Fig 2 is a part cross sectional view on line 2-2 of Fig 1.

Fig 3 is a view in the direction of arrow 3.

Referring to Figs 1 to 3. In Fig 1 a cutter head 10 is comprised as follows: A member 12 in the form of a flat plate has a connecting piece 14 affixed thereto for the purpose of connecting the cutter head 10 to a machine tool (not shown) for rotation thereby. The piece 14 terminates in a cylindrical portion 16 which in a preferred use, is gripped by the jaws of a machine tool robot arm (not shown).

The member 12 supports an electric motor 18 a drive shaft 20 of which passes through the member 12 and terminates in a gear wheel 22 which is vertically spaced from the underside of the member 22. The member 12 includes a pair of linear bill races 24, 26.

A block 28 is positioned beneath the member 12 and includes linear ball races 30, 32 which respectively cooperate with linear ball races 24, 2 and thus enable linear movement of the block 28 relative to the member 12 in a direction into and out of the plave of the drawing as viewed in Fig 1.

The block 28 also carries a toothed rack 34 which is engaged by the gearwheel 22. When the motor 18 rotates the gear wheel 22, the linear movement of block 28 is effected, in a direction dependent on he direction of rotation of the gearwheel 22.

Referring now to Fig 2. The bloc 28 carries an electric motor 18a. A drive shaft 20a passes through the block 28 and terminates in a gearwheel 22a which is vertically spaced from the underside cf the block 28. A further block 36 is provided underneat block 28 and is supported therefrom by further linear ^all race devices 38, 40. These devices are arranged so as to lie normal to the races 24, 26, 30 and 32. Thus, the further block 36 can move in directions normal to the directions of movement of the block 28.

The gearwheel 22a engages a toothed rack 34a and an operation of the motor 18a the linear ovement of block 36 is effected, again in directions irTa an out of the plan of the drawing as viewed in Fig 2.

The block 36 is bored to receive a tube 38 and has a screwed spigot 41 on which to receive he cutter 42. The tube 38 contains the wiring and/or piping (not shown) from the machine tool (not shown) to ta cutter 42.

Referring now to Fig 3. The member 12 has a slot 44 formed therein, which is open at one ed 45. The block 28 has a rectangular aperture 46 former through it. Both the slot 44 and aperture 46 are shown n Figs 1 and 2.

On first assembly of the cutter head 10, block 28 is positioned under the member 12 such that the ends of the aperture 46 coincides with the sides cf the slot 44. The block 36 is positioned under block 28 such the tube 38 extends upwardly and its axis coincides with the centre of the aperture 46 in clock 28. The final positioning is effected to make the distance between the tube 38 and the closed end of the slot 44 identical with that between the tube 38 and the sidewalls of the slot 44.Thereafter the gearwheels 22 and 22a are put in engagement with their respective toothed racks 34, 34a which then extend equi-distant either side of tefr respective gearwheels 22, 22a, so that block 36 along with tubes 38 and the cutter 42 are confined to move lengthwise of and only within the aperture 46 and block 28 along with motor 18a, can move lengthwise of the sio 44. Any known suitable stop means (not shown) can be tilised for the purpose of preventing the rack 34a from running out of contact with the associated gearwheel 22a.

The cutter 42 may be a pasma cutter. Alternatively it could be a laser cutter. However, within limitations which the man skilled in the fetid will recognise after reading this specification, metal parers as opposed to metal vapourisers can be used, eg an end mill cutter.

The machine tool (not shown) to which the cutter head of the present invention 111 be fitted, is suitable for trepanning and/or profile cutting operations wherein shaped panels are cut from sheet metal.

In operation, where cuts are to be taken in straight lines, the machine tool will have the cutter head bodily.

However, where say, two strait lines are to be cut at some angle to each other, eg as the two sides of a square, and it is desired that they be joined by a radiussed line, then the cutter head is pre set by operating an appropriate one cf the motors 18, 18a, to displace the cutter 42 from its original position where its axis coincides with the axis of the cutter head 10.

The magnitude of displacement Will equal the magnitude of the desired radius.

The machine tool (not sh m) positions the cutter head 10 so that the axis of the cutter 42 is over a point from which it is desired to start cutting a line, and the axis of the cutter head 10 is directly behind the axis of the cutter 10, ie a line connecting the axes will be normal to the direction of the line to be cut. Movement bodily is continued until the cut reaches the point where the radius is to be started, whereupon the bodily movement is stopped and the cutter head 10 is rotated about its axis. The cutter 42 is thus caused to orbit about the head axis over a distance which causes the required arcuate length to be cut. Thereafter movement of the head 10 bodily is resumed to cause cutting of the next straight portion of the profile.

It is clear from the foregoing description of how blocks 28 and 36 are connected, that they can be roved relative to each other, ie by one remaining static and the other being moved, cr by being moved simultanecusly.

Thus by appropriate actuation of motors 18 and 18a multiple curvature paths may be traversed by the utter 42, by itself or in conjunction with bodily movement of the cutter head 10. Such diversity of movement is best achieved by computer control.

Claims (7)

Claims:

1. A machine tool cutter head comprising a member rotatably connectable to a machine tool and including a cutter which cuts with energy derived from light or a gas and which is mounted on said member for movement bodily relative thereto in linear directions laterally of the axis of rotation of said member, said movement being effected by linearly moveable force applying means which are connected to a pair of motor driven gears for actuation.

2. A machine tool cutter head as claimed in claim 1 wherein said directions of linear movement of the cutter are on paths normal to each other.

3. A machine tool cutter head as claimed in claim 1 or claim 2 wherein the force applying means comprises a pair of toothed racks, each of which is engaged by a respective one of said gears.

4. A machine tool cutter head as claimed in claim 3 and including a flat member surmounting a first block which is connected thereto via first linear ball ball races and a second block surmounted by said first block and which is connected thereto via linear ball races which are orientated such that their lengths are normal to the lengths of said first linear ball races, the arrangement being such that the first and second blocks can move linearly relative to the flat member and to each other.

5. A machine tool cutter head as claimed in claim 4 wherein said cutter is supported by the second block for movement therewith simultaneously with or relative to the first block and the flat member.

6. A machine tool cutting head as claimed in any previous claim wherein said cutter head is adapted for gripping by the jaws of a robot arm which is connected to said machine tool.

7. A machine tool cutting head as claimed in any previous claim adapted for use on a computer controlled machine tool.