GB2145429A

GB2145429A - Treating a workpiece in situ

Info

Publication number: GB2145429A
Application number: GB08419378A
Authority: GB
Inventors: Robert Lawson Sharkey
Original assignee: HONES Ltd ANDREW MASTER; ANDREW MASTER HONES Ltd
Current assignee: HONES Ltd ANDREW MASTER; ANDREW MASTER HONES Ltd
Priority date: 1983-07-29
Filing date: 1984-07-30
Publication date: 1985-03-27
Also published as: GB8320527D0; GB8419378D0

Abstract

Apparatus for treating in situ a surface of a workpiece comprises a base member which carries clamping means for engaging the workpiece, a rotatable member mounted on the base member and continuously rotatable thereon so as to orbit the workpiece surface (either externally or internally) a treatment head (eg a plating head, a grinding wheel or a tool bit) on the rotatable member and means for rotating the rotatable member. In the embodiment of Figs. 1-3 the apparatus includes a fixed section comprising a thrust ring 4 which clamps the workpiece, and a rotatable section comprising driven rings 8, 9. Ring 9 has connected to it four anode holders 11 on which anodes (12, Fig. 1) are mounted. Plating fluid is supplied via an inlet passage (13), chamber (14), outlet (16) and bores (17) in the anodes (12). In the embodiment of Fig. 4 a central rotatable shaft (31) having a through bore carries an operating head (33) on which are mounted anodes (34). Plating solution is fed via pipe (35) and gland (37). Brass ring (36) receives current for powering anoes (34). <IMAGE>

Description

SPECIFICATION A method and apparatus for treating a workpiece This invention relates to a method and apparatus for treating a workpiece.

In building up the surface of a worn workpiece by plating, for example nickel and/or chromium plating, it has generally been necessary to remove the workpiece from its inuse situation and conduct the plating operation in a plating bath. This is time-consuming and can cause considerable problems in having the workpiece removed and out of action for long periods.

It has also been proposed to build up the surface by plating in situ by applying a handheld plating head to the workpiece and rotating the workpiece. Plating solution is pumped through the plating head onto the workpiece surface and an electric current is passed through it. The plating head is then moved along the rotating workpiece and a deposit builds up on the workpiece surface.

The problem of in-situ treatment of workpieces has also been met in the field of grinding, where it is known to mount a portable grinding machine, through bearing pads, on a workpiece such as a crankshaft bearing and rotating the workpiece against a grinding wheel on the machine. This makes it necessary for the workpiece to be rotatable.

In situations where the workpiece is fixed it has hitherto been possible to grind only a portion of the surface at each operation, as portable grinding machines in which the grinding wheel itself is rotatable around the workpiece have been capable of so doing through less than 360 degrees. Thus a reciprocal rotation of the wheel was all that was possible, resulting in incomplete surface grinding in a single operation.

According to the present invention there is provided apparatus for use in treating in situ a surface of a workpiece, comprising a base member which carries clamping means for engaging a workpiece, a rotatable member mounted on the base member and continuously rotatable thereon so as to orbit around the workpiece, a treatment head on the rotatable member for treating the workpiece surface, and drive means for rotating the rotatable member.

The treatment head is preferably rotatable continuously through successive 260 degree rotations and may be movable along the workpiece during rotation, so that a cylindrical workpiece can be treated from one end to the other over at least part of its surface in a single operation.

The treatment head may be an anodic plating head through which electrical current is passed. The workpiece acts as a cathode, so that the current flows from one to the other through plating fluid supplied between the anode and the workpiece.

Passageway means are preferably provided through the base member and the rotatable member for supply of plating fluid, for example, electrolyte, to the plating head. The passageway means may include an annular chamber into which a passage opens from the base member for supply of the plating fluid.

The chamber preferably has an outlet leading to the plating head. Thus, on rotation of the plating head, plating fluid is supplied through the static base member to the annular chamber, and thence through the outlet to the plating head as the outlet moves with the plating head around the chamber. A continuous supply of plating fluid to the head is thus obtained.

The apparatus may be adapted for use in treating either an internal or an external surface of the workpiece. In the former case the workpiece may be held in a clamp while the plating head enters an aperture in the workpiece and is mounted on a fixed support which may be the same as or different from a support on which the clamp is mounted; thus the base member may be formed as a number of component parts.

The treatment head can be for example a plating head, a grinding wheel or a tool bit, and preferably two or more of these can be interchanged on the apparatus depending on the particular treatment required.

A lead screw or other means may be provided for traversing the treatment head along the workpiece.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a front view of apparatus of this invention; Figure 2 is a part-sectional view of the apparatus of Fig. 1; Figure 3 is a rear view of the apparatus of Fig. 1; and Figure 4 is a schematic side view of a further embodiment of the invention for use in plating an internal face of a workpiece.

Referring to the drawings, the apparatus of the embodiment of the invention shown in Figs. 1 to 3 is in the form of a machine for plating, grinding or turning a workpiece in situ, although the drawings show the machine in its plating mode.

The machine is made in an upper portion 1 and a lower portion 2 which is secured to the upper portion 1 in use by means of bolts 3 (Fig. 3) at each side. The machine has a fixed, non-rotating section for clamping to a workpiece, and a rotatable section carrying treatment heads for orbiting around the workpiece.

The fixed section has a Polypenco baffle and thrust ring 4 which on joining of the upper and lower portions 1, 2 of the machine clamps around the workpiece to hold the machine rigidly on the workpiece. Also on the fixed section are an annular brush holder 5 whose inner diameter is the same as that of the ring 4, an electrical supply brush 6 mounted on the holder 5, and a further baffle ring 7.

The rotatable section of the machine has a pair of driven rings 8, 9 each having a Vshaped groove 29 around its periphery for receiving a drive belt, the ring 8 having projecting from its inner face four bearing pads 10 of Tuffnol, being material which is acid resistant, electrically non-conducting and rigid. The pads 10 bear in use against the workpiece to hold the rotating section of the machine in accurate relationship thereto.

The ring 9 carries similar bearing pads 10 and also has connected to it four anode holders 11 on which anodes 1 2 are mounted.

Each anode holder 11 has an inlet passage 1 3 leading to a chamber 14 through which a bolt 1 5 extends, being screwed into the body of the holder 11. The chamber 14 has an outlet 1 6 which leads to the anode 1 2 through which bores 1 7 are formed which open on the anode's outer face. A spring 1 8 extends around the bolt 1 5 and acts to push the anode towards the workpiece passing through the centre of the machine, the action of the spring 18 being controlled by the bolt 1 5. The bolt 1 5 carries a stop member 1 9 which closes off the outlet 16 when the bolt is fully inserted.

A pair of shafts 20 pass through the anode holder 11 and are held in the holder by a detent mechanism (not shown). The other end of the shafts 20 are connected by a handle 21 which is held against a side face of the ring 8 by a cam lever (not shown). This allows for easy and quick removal of the holder 11 by releasing the cam and withdrawing the shafts 20 from the detent in the holder; the holder 11 is then free to be lifted from the machine.

The inlet passage 1 3 of the holder communicates with a system of passageways for supply of plating solution to the anode 1 2.

The passageways comprise a bore 22 through the ring 9, an annular passage 23 between the ring 9 and a fixed guide bar 24, and a duct 25 through the guide bar 24. The duct 25 opens at the periphery of the machine for connection to an external supply of solution.

Four guide bars 24 are provided, each being set into Polypenco holders 26 which are thrust against the rings 8, 9 by springs 27 to provide an effective seal.

The annular passage 23 ensures continuous communication between the duct 25 in the static guide bar 24 and the bore 22 in the rotating ring 9.

The ring 8 carries on its side face a brass slip ring 28 which engages the brush 6 to provide electrical power for the anodes.

In use, the machine is fitted over a cylindrical workpiece by bolting together the upper and lower portions 1 and 2 around the workpiece. The inside diameter of the machine is preset according to the outside diameter of the workpiece by selecting the appropriate thickness of the baffle and thrust rings 4, 7.

The machine is thus firmly clamped on the workpiece.

Continuous drive belts are engaged in the V-grooves 29 and connected to a motor to rotate the rings 8, 9 and other parts of the rotatable section of the machine.

The anodes 1 2 are moved against the workpiece by unscrewing the bolts 15, thus opening access to the outlet 1 6 and allowing the spring 18 to push the anode 1 2 positively towards the workpiece.

The duct 25 is connected to a supply of plating solution, for example nickel plating solution, and the machine is started up by actuating the drive belts. This causes the anodes to orbit around the workpiece while plating solution passes through the duct 25, annular passage 23, bore 22 and into the anode holder through the inlet passage 1 3.

The solution then passes from the chamber 1 4 past the stop member 1 9 to the anode and thence through the bores 1 7 to the workpiece.

Electric current is applied through the brush 6 and slip ring 28 to the anodes 1 2, and with the workpiece connected to render it cathodic the current flows between the anodes and workpiece through the plating solution. As the anodes 1 2 move round the workpiece therefore nickel or other deposit builds up on the workpiece surface.

When the deposit has reached a desired depth the electric current is switched off and the machine is stopped. The anodes 1 2 and anode holders 11 can then be removed as previously described and replaced with one or more grinding wheels or tool holders which can be similarly mounted on the machine. The machine can then be used to grind or turn the workpiece.

In its grinding or machining mode the operating head can be traversed along the workpiece by means of a lead screw 30.

Instead of having the anode holders 11 mounted to one side of the machine (Fig. 2) which is useful for treating up to the extreme end of a workpiece, they can be mounted centrally of the machine between the baffle and thrust rings 4 and 7.

The machine in the embodiment illustrated in Fig. 4 has a central rotatable shaft 31 having a through bore. At its extreme end the shaft 31 carries an operating head 33 on which are mounted peripherally a number of anodes 34 rotatable with the shaft and radially movable on it. The anodes 34 have through ducts which communicate with the bore in the shaft 31.

At its other end the shaft 31 has a brass ring 36 which receives an electric current for powering the anodes 34. A gland 37 has a through passage connecting with the bore 32 and into this is fed plating solution through a pipe 35.

The operation of the Fig. 4 machine is as follows. The shaft 31 and anodes 34 are rotated by an external drive, and plating solution is pumped to the anodes 34 through the passage, bore and ducts, and with the workpiece cathodic electric current passes through the solution between the anodes 34 and workpiece to deposit metal on the workpiece surface.

Alternatively, the plating solution can simply be pumped to the anodes 34 externally of the machine, and subsequently drained off; this is usually practicable only when the machine is not used in situ.

Modifications and improvements may be made without departing from the scope of the invention.

Claims

1. Apparatus for use in treating in situ a surface of a workpiece, comprising a base member which carries clamping means for engaging a workpiece, a rotatable member mounted on the base member and continuously rotatable thereon so as to orbit around the workpiece, a treatment head on the rotatable member for treating the workpiece surface, and drive means for rotating the rotatable member.

2. Apparatus according to Claim 1, wherein the treatment head is selected from a plating head, a grinding wheel and a tool bit.

3. Apparatus according to Claim 2, wherein the treatment head is interchangeable.

4. Apparatus according to Claim 2 or 3, wherein the treatment head includes an anode.

5. Apparatus according to Claim 4, wherein passageway means are provided through the base member and the rotatable member for supply of plating fluid to the anode.

6. Apparatus according to Claim 5, wherein the passageway means includes an annular chamber of which a first wall portion is formed by part of the base member and has through it an inlet for plating fluid and a second wall portion is formed by part of the rotatable member and has through it an outlet for plating fluid.

7. Apparatus according to claim 6, wherein a fluid-tight seal is provided between the first and second wall portions.

8. Apparatus according to any one of Claims 5 to 7, wherein the anode has apertures therethrough, the apertures being in fluid communication with the passageway means.

9. Apparatus according to any one of the preceding Claims, wherein the clamping means is adapted to engage an internal face of a workpiece and the treatment head is arranged to orbit within the workpiece around said internal face.

10. Apparatus according to any one of Claims 1 to 8, wherein the base member has a through bore within which the workpiece may pass and the treatment head is arranged to orbit around an external face of the workpiece.

11. Apparatus according to Claim 10, wherein the base member has first and second relatively movable portions which can be moved apart to receive the workpiece between them and locked together to form said through bore.

1 2. Apparatus according to any of the preceding Claims, wherein the treatment head extends beyond an end face of the base member.

1 3. Apparatus according to any one of Claims 1 to 11, wherein the treatment head is disposed between the opposite ends of the base member.

1 4. Apparatus according to any one of the preceding Claims, wherein the treatment head is movable relative to the clamping means towards and away from the workpiece.

1 5. Apparatus according to any one of the preceding Claims, wherein the treatment head is movable relative to the clamping means along the workpiece.

1 6. Apparatus for use in treating in situ a surface of a workpiece, substantially as hereinbefore described with reference to and as shown in Figs. 1, 2 and 3 of the accompanying drawings.

1 7. Apparatus for use in treating in situ a surface of a workpiece, substantially as hereinbefore described with reference to and as shown in Fig. 4 of the accompanying drawings.