US3596409A

US3596409A - Methods and machines for grinding crankshafts

Info

Publication number: US3596409A
Application number: US849470A
Authority: US
Inventors: Eric Levesley
Original assignee: English Steel Corp Ltd
Current assignee: English Steel Corp Ltd
Priority date: 1968-08-27
Filing date: 1969-08-12
Publication date: 1971-08-03
Anticipated expiration: 1988-08-03

Abstract

A machine for grinding crankshafts has an annular carrier rotatable coaxially around a crankpin of a stationary crankshaft, and a pair of pulleys are mounted on the carrier in such a manner that one of them can be moved towards the axis of the carrier, and abrasive belt is trained around the pulleys with its abrasive surface facing outwards, and one of the pulleys is adapted to be driven, so that as the belt orbits with the pulleys around the crankpin the belt is driven in contact with the crankpin for the grinding operation. At the contact point, the back of the belt is in contact with one of the pulleys.

Description

United States Patent inventor Eric Levesley Sheffield, England Appl. No. 849.470 Filed Aug. 12, 1969 Patented Aug. 3, 1971 Assignee English Steel Corporation Limited Priority Aug. 27, 1968 Great Britain 40892/68 METHODS AND MACHINES FOR GRINDING CRANKSHAFI' S 9 Claims, 1 Drawing Fig.

U.S. Cl 51/135 B24b 21/00 Field of Search 51/135- [56] References Cited UNITED STATES PATENTS 3,124,908 3/1964 Wingetal 51/140 Primary Examiner-Othell M. Simpson Attorney-Lowe and King ABSTRACT: A machine for grinding crankshafts has an annular carrier rotatable coaxially around a crankpin of a stationary crankshaft, and a pair of pulleys are mounted on the carrier in such a manner that one of them can be moved towards the axis of the carrier, and abrasive belt is trained around the pulleys with its abrasive surface facing outwards, and one of the pulleys is adapted to be driven, so that as the belt orbits with the pulleys around the crankpin the belt is driven in contact with the crankpin for the grinding operation. At the contact point, the back of the belt is in contact with one of the pulleys.

METHODS AND MACHINES FOR GRINDING CRANKSI-IAFTS This invention relates to a machine for grinding crankshafts, more particularly with large diameter crankpins.

One object of the invention is to effect the grinding of a crankshaft with the crankshaft stationary and with a grinding device orbiting around the crankpin, thus avoiding any need to counterbalance the crankshaft.

Another object is to keep down the size of the grinding device, so as to keep down also the mass orbiting round the crankshaft.

A further object is to avoid the use of grinding wheels, because of their high cost, the. difficulties involved in handling them, and the difficulty of maintaining accurate grinding without frequent trueing or replacement of the grinding wheel.

Yet another object of the invention is to provide a grinding device with readily interchangeable grinding means so that optimum stock removal and optimum surface finish can be easily obtained.

According to the invention, a preferred embodiment of the machine for grinding crankshafts comprises abase, pedestals for supporting a crankshaft, interconnected saddles carrying the pedestals and reciprocable on the base in the direction parallel to the lengthwise direction of a crankshaft supported by the pedestals, cross-slides between the pedestals and the saddles, an upright frame across the base, an annular carrier rotatable on the frame with the axisof the carrier parallel to the lengthwise direction of said, crankshaft supported by the pedestals, power means for rotating the carrier about its axis, a pair of pulleys extending to one side of the carrier and parallel to its axis, a flexible abrasive belt trained around the pulleys with its abrasive surface facingoutwards, power means for driving one of the pulleys and means for moving one of the pulleys towards and away from the axis of the carrier to apply the belt in contact with the crankpin for the grinding operation.

With a crankshaft supported-by the pedestals, and with a crankpin to be operated on aligned .with the axis of the carrier and in the same general plane as thev abrasive belt and pulleys, the carrier is rotated around the crankpin to cause the belt to orbit the same and simultaneously the abrasive belt is driven around the pulleys; the one pulley being moved towards the axis of the carrier to bring the abrasive belt into grinding contact with the crankpin around which the belt orbits.

The other pulley is preferably a driven one and said one pulley for applying the abrasive belt to a crankpin is an idle pulley. The idle pulley maybe mounted for movement towards and away from the driven pulley for adjusting the tension in the belt and for facilitating changing of belts. In addition, an idler jockey pulley may be provided for tensioning the belt. The idle pulley is preferably very;largejrt'f diametegas ompared with the driven pulley, and preferably has a serrated or otherwise treated periphery enhancing thedriving grip of the belt. The means for driving the driven pulley is conveniently an electric motor also mounted on the carrier, with power supplied through pickup rings and sliding contacts at the interface between the carrier and the upright frame.

The belt-applying or idle pulley is preferably carried by a swinging plate with its axis the same'as the driven pulley, for withdrawal of the beltwell clear of a crankshaft when transferring from one crankpin to another.

Another and separate electricmotor may provide both for rotation of the carrier and, when required, reciprocation of the saddles.

The pedestals are preferably provided with aligned bearings for the journals of a crankshaft, the bearings being split lengthwise for insertion and removal of the crankshaft jour nals and provided with clamping bolts or studsfor gripping the journals in the bearings, so that a crankpin to be ground can be brought into coaxial alignment with the carrier.

The preferred embodiment of machine according to the invention will now be described, by way of example only, with reference to the accompanying drawing, which is a perspective view of the machine with a crankshaft in position for the grinding of one of its crankpins.

The machine comprises a base i, pedestals 2 for supporting a crankshaft 3, a pair of saddles 4 interconnected by a shaft 5 and reciprocable on the base in a direction parallel to the lengthwise direction of the crankshaft, cross-slides 6 supporting the pedestals on the saddles, an upright frame 7 across the base, and an annular carrier 8 rotatably mounted on the frame in bearings (not visible). The axis of the carrier 8 parallel to the lengthwise direction of the crankshaft, and an electric motor 9 is provided for driving the carrier 8 through a reduction gear 10 and a gearbox 11 preferably incorporated in the frame 7). The motor 9 also effects reciprocation of the saddles 4 through a lead screw 12.

The cross-slides 6, on which the pedestals 2 are bolted, are traversed by usual lead screws (not visible). These lead screws may be provided with square-ends l3 engageable by any suitable handle, and with positioning dials 14. The pedestals are provided with split bearings 15 and cooperating clamping bolts or studs 16 for gripping the journals 1? of the crankshaft 3. As shown, a crankpin 18 to be ground is positioned in coaxial alignment with the carrier 8.

The carrier is provided with parallel guides 19 for a radially adjustable slide 20A carrying a pair of pulleys 21A, 2113 extending parallel to the crankpin 18. A flexible abrasive belt 22 is trained around the pulleys with its abrasive surface facing outwards. A jockey pulley 23 is provided for tensioning the belt, and an electric motor 24 drives the pulley 213 through a gearbox 25. Power is supplied to the motor 24 at the interface between the carrier 8 and the frame through pickup rings '26 extending around the periphery of the carrier 8 and sliding contacts (not visible) housed in a box 27 on the frame 7. The pulley 21A is an idle pulley, and has a serrated periphery 28 enhancing the driving grip of the belt 22 therewith. The

pulleys

21A and 23 are carried by a plate 29 mounted to swing about the axis of the driven pulley 213 to permit withdrawal of the belt 22 well clear of the crankshaft when transferring from one crankpin to another. The plate 29 being shown in its innermost position in which it is secured by a bolt 30 passing through an arcuate slot 311 in the swinging plate. The jockey pulley 23 is mounted on a bolt 32 adjustable along a slot 33 in the plate 29, but a screw adjustment could be provided alternatively. The slide 20A is movable along the guides 19 by screws (not visible), said screws being recessed into the carrier 8 and rotatable manually. However, a further motor (with gearbox) for driving the screws could be provided on the carrier with power supplied through further pickup rings on the periphery of the carrier and cooperating sliding contacts in the box 27.

The position of each of the crankpins 18 to be ground is adjusted until it is coaxially aligned with the outer or operative face of the carrier 8. Then, with the abrasive belt 22 in contact with the crankpin and the back of the belt in contact with the pulley 21A, the carrier is rotated around the crankpin and the belt is simultaneously driven around the

pulleys

21A, 21B, 23, to effect grinding of the crankpin.

The belt 22 is light and the

pulleys

21A, 21B, 23 and the other orbiting parts can be made light in weight as compared with a grinding wheel of sufficient diameter for guiding crankshafts of comparable size. Furthermore, the belt 22 is readily replaceable and interchangeable, and is relatively inexpensive, regardless of the grit and grade, as compared with a grinding wheel. The belt 22 and pulley 21A are narrow enough to suit the shortest crankpin likely to be encountered in a crankshaft of comparable size, and the crankshaft 3 may be moved axially, by moving the saddles 4 (and with them the cross-slide 6 and the pedestals 2) by means of the lead screw 12 to grind the whole length of each crankpin. Greater movement of the crankshaft provides for transfer from one crankpin to another, after the plate 29 has been swung to bring the pulley 21A and belt 22 clear of the intervening crankwebs.

' pump, supply pipes and rains (not shown) circulate coolant,

which is cleaned by a centrifuge or a magnetic separator.

Additional operational attachments may be provided on the carrier 8, e.g., means carried by another slide 208 between the guides 19, for grinding and polishing the faces of the crankweb and the fillet between said crankwebs and the crankpins. Advantageously, this additional operation can be carried out simultaneously with grinding and polishing of the crankpin in accordance with the teaching.

l claim:

1. A machine for grinding the crankpins of crankshafts comprising:

a base,

pedestals for supporting a crankshaft,

interconnected saddles carrying the pedestals and reciprocable on the base in the direction parallel to the lengthwise direction of a crankshaft supported by the pedestals cross-slides between the pedestals and the saddles,

an upright frame across the base,

an annular carrier rotatable on the frame with the axis of the carrier parallel to the lengthwise direction of a crankshaft supported by the pedestals,

power means for rotating the carrier about its axis,

a pair of pulleys extending to one side of the carrier and parallel to its axis,

a flexible abrasive belt trained around the pulleys with its abrasive surface facing outwards to engage the crankpins,

power means for driving one of the pulleys and means for moving one of the pulleys towards and away from the axis of the carrier to applythe belt in contact with the crankpin for the grinding operation.

2. A machine as in claim 1, wherein the other pulley is a driven one and the pulley for applying the abrasive belt to a crankpin is an idle pulley.

3. A machine as in claim 1, wherein a jockey pulley is provided for tensioning the belt.

4. A machine as in claim 2, wherein the idle pulley is very large in diameter as compared with the driven pulley.

5. A machine as in claim 2, wherein the idle pulley has a serrated periphery.

6. A machine as in claim 1, wherein the means for driving the driven pulley is an electric motor also mounted on the carrier, pickup rings and sliding contacts being provided at the interface between the annular carrier and frame to supply power to said motor.

7. A machine as in claim 2, wherein the belt-applying pulley is carried by a swinging plate with its axis being the same as the driven pulley to permit withdrawal of said belt well clear of a crankshaft when transferring from one crankpin to another.

8. A machine as in claim 6, wherein a separate motor provides power both for rotation of the carrier and reciprocation of the saddles.

9. A machine as in claim 1, wherein the pedestals are provided with aligned bearings for receiving the journals of a crankshaft, the bearings being split lengthwise for insertion and removal of the crankshaft journals and clamping bolts or studs for gripping the journals in the bearings.

Claims

1. A machine for grinding the crankpins of crankshafts comprising: a base, pedestals for supporting a crankshaft, interconnected saddles carrying the pedestals and reciprocable on the base in the direction parallel to the lengthwise direction of a crankshaft supported by the pedestals cross-slides between the pedestals and the saddles, an upright frame across the base, an annular carrier rotatable on the frame with the axis of the carrier parallel to the lengthwise direction of a crankshaft supported by the pedestals, power means for rotating the carrier about its axis, a pair of pulleys extending to one side of the carrier and parallel to its axis, a flexible abrasive belt trained around the pulleys with its abrasive surface facing outwards to engage the crankpins, power means for driving one of the pulleys and means for moving one of the pulleys towards and away from the axis of the carrier to apply the belt in contact with the crankpin for the grinding operation.

5. A machine as in claim 2, wherein the idle pulley has a serrated periphery.