GB2135611A

GB2135611A - In situ machine tool

Info

Publication number: GB2135611A
Application number: GB08303814A
Authority: GB
Inventors: William Gordon Cook; Arthur Edwin Kerr; Henry Blair
Original assignee: William G Cook Engineering
Current assignee: William G Cook Engineering
Priority date: 1983-02-11
Filing date: 1983-02-11
Publication date: 1984-09-05
Also published as: GB8303814D0

Abstract

The machine tool, for facing an annular surface, e.g. a race of a crane slewing mechanism, comprises a rotary table assembly itself comprising a stationary ring (1) having external gear teeth, and, rotatable within the ring (1) a circular table (2). A radial arm (6) is adjustably mounted on and extends diametrically of the table (2). The arm (6) carries a milling cutter assembly (7) which is adjustable along the arm (6) and can be mounted in different attitudes i.e. up, down or outwardly. The arm (6) also carries a driving unit (8) coupled to a pinion (9) in mesh with the teeth on the ring (1), the pinion (9) being rotatably mounted on the table (2). The milling cutter assembly (7) and the driving unit (8) have respective hydraulic motors (14 and 18), fed by circuits via a hydraulic coupling (5). <IMAGE>

Description

SPECIFICATION In Situ Facing Machine Tool This invention relates to an in situ facing machine tool particularly for use in refacing the surfaces of the races of a slewing mechanism of cranes and the like.

It is known to provide in situ facing machine tools wherein a single cutting point orbits about a gradually reducing diameter. This requires close monitoring since degradation of the single cutting point results in a poor finish of the surface being refaced. Furthermore, cutting time is protracted due to the high number of passes which require to be made.

An object of the invention is to obviate or mitigate the above disadvantages.

According to the invention there is provided an in situ facing machine tool comprising a rotary multipoint cutting tool mounted to orbit about a fixed axis, and means for adjusting the radius of the orbit.

Thus, in use, in refacing say a horizontal surface an annular surface of a finite width is machined. If it is necessary to increase the width of the annular surface machined this can be done easily by adjusting the radial position of the cutting tool and performing another pass.

Furthermore, since there is a plurality of cutting points there is less risk of a poor finish and consqeuently less need for close monitoring.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:~ Fig. 1 is a plan view of an in situ facing machine tool; Fig. 2 is a side view of the machine tool shown in Fig. 1; Fig. 3 is an end view to an enlarged scale of the machine tool shown in Fig. 1; and Fig. 4 is a diagram of a hydraulic circuit for use with the machine tool shown in Fig. 1.

In the drawings, a rotary table assembly comprises a stationary ring 1 having external gear teeth, and, rotatable within the ring 1 a circular table 2 presenting an upwardly-facing flat surface. A guide is mounted on the flat surface of the table 2 and comprises two angles 3 surmounted by an inverted U-shaped bracket 4 disposed centrally of the table 2. A rotary hydraulic coupling 5 is mounted atop the bracket 4.

A radial arm 6 of box section is mounted between the angles 3 and between the flat surface of the table 2 and the bracket 4 and extends diametrically relative to the table 2. The arm 6 may be either fixed or slidably adjustable.

For this latter purpose holes in the sides of the arm 6 may be alignable with holes in the angles 3 to receive screws. The arm 6 carries on one side at a radius remote from the table 2 a milling cutter assembly 7. The arm 6 also carries on the other side at a radius nearer the table 2 a driving unit 8 coupled to a pinion 9 in mesh with the external gear teeth on the fixed ring 1. The pinion 9 is journalled in a bracket 10 mounted on the flat surface of the table 2.

The milling cutter assembly 7 comprises a mounting plate 11 having holes alignable with holes in the side of the arm 6 to receive screws whereby the assembly 7 can be mounted at a desired position along the arm 6 and at desired height relative to the arm 6. Mounted on the mounting plate 11 is a hand-feed mechanism 12 and mounted on the mechanism 12 is a milling head 13. The milling head 13 carries a hydraulic motor 14 for driving a spindle 15 journalled in the milling head 13. On the lower end of the spindle 15 is push-fitted an exchangeable milling tool 16 provided on its bottom face with a ring of cutting points.

The driving unit 8 comprises an angled mounting bracket 17 having holes alignable with holes in the side of the arm 6 to receive screws whereby the unit 8 can be mounted at a desired position along the arm 6. Mounted on the bracket 17 is a hydraulic motor 18. The shaft of the motor 18 has a worm in mesh with a worm wheel on a spindle 19. These items are journalled in a casing 20 mounted on the bracket 17. At the lower end of the spindle there is a sprocket 21 about which is entrained a driving chain 22. The chain 22 is also entrained about a larger sprocket 23 fast on a shaft carrying the pinion 9. A thrust screw (not shown) is mounted on the bracket 17 to take up slack in the chain 22. Other means for taking up the slack could also be used.

The machine tool is mounted between the upper and lower races of a slewing mechanism of a crane, the upper race and the structure thereabove having previously been jacked up and the rolling bearing elements having been removed. The rotary table assembly is mounted centrally within the lower race. Referring to Fig. 4, the lines 23, 24, 25 and 26 extend from the hydraulic motors 14 and 18 to the coupling 5 and the remaining items of the hydraulic circuit are at fixed locations remote from the machine tool, hoses leading from the coupling 5 to two manually-operative directional control valves 27 and 28. The hydraulic circuit comprises a pneumatic motor 29 driving a hydraulic pump 30 via a coupling 31. The pump 30 draws hydraulic fluid from a reservoir 32 via a filter 33 and a shutoff valve 34 and delivers hydraulic fluid through a line 35.The delivery line 35 branches into two lines 36 and 37 leading, via flow regulators 38 and 39 to the valves 27 and 28. Two return lines from the valves 27 and 28, lead back to the reservoir 32 via a line 40 parallel connected filter 41 and check valve 42. The delivery line 35 is also connected to the reservoir 32 via a pressure relief valve 43. Each one of the valves 27 and 28 has a detest 44 for releasably retaining the valve in a central position where the pump 30 merely returns hydraulic fluid to the reservoir 32 via the pressure relief valve 43 and both sides of the associated hydraulic motor 14, 1 8 are connected to the line 40.

One motor 14 serves to drive the milling tool 16 while the other motor 18 serves to orbit the tool 16. In so doing, the tool 16 describes a rosetting cut on the horizontal surface of lower race so as to reface the same. It is also possible to reface the horizontal surface of the upper race or to reface an inwardly-facing cylindrical surface of either race by inverting the assembly 7 or positioning it at 900 to that as shown. It is also possible to invert the whole machine tool. Thus for each setting of the machine tool an annular surface of a finite width can be refaced. This is to be distinguished from known in situ facing machine tool wherein a single cutting point orbits about a gradually reducing diameter.

Claims

1. An in situ facing machine tool comprising a rotary multipoint cutting tool mounted to orbit about a fixed axis, and means for adjusting the radius of the orbit.

2. A machine tool according to claim 1, wherein the cutting tool is mounted on a radial arm which itself is mounted on a table rotatable about the fixed axis.

3. A machine tool according to claim 2, wherein the cutting tool and arm have alignable holes for selectively positioning the cutting tool along the arm.

4. A machine tool according to claim 2 or 3, wherein the arm and the table have alignable holes for selectively positioning the arm along a diameter of the table.

5. A machine tool according to claim 2, 3 or 4, wherein the cutting tool can be mounted on the arm in different attitudes.

6. A machine tool according to claim 2, 3, 4 or 5, wherein the table is rotatable within a stationary ring having gear teeth and in a pinion rotatably mounted on the table is in mesh with the teeth of the ring.

7. An in situ machine tool substantially as hereinbefore described with reference to the accompanying drawings.