US3548547A

US3548547A - Apparatus for microfinishing crankpins of crankshafts

Info

Publication number: US3548547A
Application number: US647866A
Authority: US
Inventors: Heinert Runge; Karl Wieck
Original assignee: Bremer Vulkan AG Schiffbau und Maschinenfabrik
Current assignee: Bremer Vulkan AG Schiffbau und Maschinenfabrik
Priority date: 1966-06-22
Filing date: 1967-06-21
Publication date: 1970-12-22
Anticipated expiration: 1987-12-22
Also published as: FR1549225A; GB1195283A; SE335687B

Description

De.22;;1970 H,RUNGE ETAL 3,548,547

APPARATUS FOR MICROFINISHING CRANKPINS OF CRANKSHAFTS Filed June 21, 196'? 5 Sheets-Sheet 1 s 0 25 4 21 a O Q a e /N VE N TORS ATTYJ.

- Dec. 22, 1970 1 RUNGE ETAL 3,548,547

APPARATUS FOR MICROFINISHING CRANKPINS CRANKSHAFTS Filed June 21, 1967 v Sheets-Sheet 2 INVENTORS: H. Ru/vaE 4- K. W/EC ATTY Dec. 22,1970 3,548,541

APPARATUS FOR MICROFINISHING CRANKPINS OF CRANKSHAFTS Filed June 21, 1967 HVRUNGE ETAL 5 Sheets-Sheet 3 Ian- INVENTORS: H. Ru/vaE 947K WIECK ATTY DEC. 22, 1970 RUNGE ET AL 3,548,547

APPARATUS FOR MICROFINISHING CRANKPINS OF GRANKSHAFTS Filed June 21, 1967 Sheets-Sheet 4 Fig.6 55 55 49 "14/9, o I 66 g 0 o o O 54 57 2 56 3 a EX 3 60 IN VE N TOPS H Ru/vcE 9" K. M'Ecn Q LMM Dec. 22,1970 H. @NG: ETAL 3,548,541

APPARATUS FOR MI CROFINISHING CRANKPINS OF CRANKSHAFTS Filed June 21, 1967 5 Sheets-Sheet 5 IN VE N TOPS H. Kali/05.5 K. W/ECK Z gfiww United States Patent, M

ABSTRACT OF THE DISCLOSURE A device for highly accurate microfinishing of the crankpins of crankshafts as the crankshaft is supported on a lathe which rotates the crankshaft about its axis of rotation The accurate microgrinding or microfinishing of crankpins has been a substantial problem in the art because the crankpins follow a circular path of movement about the crankashaft as the crankshaft is rotated about its axis. In the present apparatus, the microgrinding or microfinishing head, or appliance carrier, is mounted on a supporting arm means which is so constructed that the transverse working axis of the microfinishing head remains closely parallel to the axis of the crankshaft and its supporting lathe, while at the same time the microfinishing head freely follows the circular path of the crankpin. This accurate control of the microfinishing head insures that the crankpin will be ground to a desired precision not possible with prior known apparatus or methods for performing the same operation. The basic concept takes several alternate forms.

BACKGROUND OF THE INVENTION In order to achieve high precision in the manufacturing or repair of crankshafts, so that the crankshafts will rotate smoothly in their bearings without vibration, it has become desirable to microfinish the crankshafts in general, and particularly the bearing pins of the crankshafts. The smooth action of the piston rods and the durability of the engine are closely related to the quality of such microfinishing. The microfinishing of the bearing pins of crankshafts has not been particularly difficult, since the bearing pins during rotation of the crankshaft on the lathe rotate about a fixed axis, remaining in substantially the same position. Therefore, the microfinishing device for finishing the said bearing pins may be fixedly mounted and so held until the desired microfinishing is completed. However, microfinishing of the crankpins of the crankshafts has been substantially more difiicult, because the crankpin moves in a circular path around the bearing pins on the axis of rotation of the crankshaft. Grinding of the crankpins before assembly is not feasible, because the grinding must be done in situ on a completed crankshaft. Further, the microfinishing is often undertaken on crankshafts being repaired.

Prior grinding devices have been known in which the microfinishing head, sometimes called the appliance carrier, is guided by and held on the crankpin itself. In this apparatus, the microfinishing head must completely surround the crankpin. It is aligned on the crankpin in such a way that the microfinishing head, as a multiple part frame, engages on the transition rods between the crankpin and the cheeks of the crankshaft by means of adjust ing screws or spring-loaded bolts. In this structure, rota tion of the frame around the axis of the pin is possible. Grinding is effected in that either the microfinishing head frame rotates around the crankpin of the crankshaft while Patented Dec. 22, 1970 l-CG it is at rest, or the frame is held while the crankshaft is rotated about its axis of rotation. In neither case does the microfinishing head have any rigid support or fixed position relative to a stationary base. The centering of the frame on the crankpin is not accurate because the necessary spring adjustment of the frame permits undesirable movement. Irregularities on the transition rods of the pin in this case may be transferred to the microfinishing head, and thus to the microfinishing tools. In this known apparatus, only relatively coarse aftergrinding may be undertaken and real microgrinding or superfinishing with any accuracy or precision is not possible.

SUMMARY 'OF THE INVENTION It is an object of the invention to make a device for microfinishing crankpins of crankshafts, in which despite the circular path of movement of the crankpin around the axis of rotation of the crankshaft, the microfinishing head may be easily adjusted and then maintained in accurate position during use. This device for microfinishing crankpins of crankshafts, in which there is relative rotation between the microfinishing tools and the crankpin is characterized in that the appliance carrier or microfinishing head is carried by a mounting which is so formed as to maintain the transverse working axis of the microfinishing head accurately parallel to the axis of rotation of the crankshaft while the said microfinishing head follows the circular path of movement of the crankpin about the crankshaft.

In the construction of the present invention, the setting up and alignment of the microfinishing device is independent of the form and nature of the transition rods of the crankshaft relative to the checks of the crankshaft. The microfinishing head is supported on a stable and accurate mount which permits the microfinishing head to follow the crankpin without affecting the fineness and accuracy of the working process. Guidance of the microfinishing device is considerably more exact than if the microfinishig head is carried by and supported directly on the crankpin. The working accuracy of the microfinishing head is considerably increased, and there is less apparatus Wear.

The construction of the mounting means having the noted capability may be carried out in various ways. In the preferred embodiment, there is a parallel arm guide means made up of two sets of parallel arms or rails, the microfinishing head being supported at the free end of a pair of parallel rails. This parallel linkage arrangement makes possible a uniform relative speed between the microfinishing tools and the crankpin so that no additional shaping error is introduced into the grinding process and a correction of any eccentricity or irregularity of the crankpin is achieved. The device may be used equally well on new crankashafts or upon those under repair.

It is an object of the invention to provide other embodiments involving the general concept and which may be used for the purpose described.

DESCRIPTION OF THE DRAWINGS FIGURE 1 shows a side elevational view, partly schematic, of a preferred embodiment of the present inven tion.

FIG. 2 is a top plan view, partly diagrammatic, of the transport slide for the microfinishing head.

FIG. 3 is an end view, partly diagrammatic, of a microfinishing head.

FIG. 4 is a cross-sectional view taken on the line IV-IV of FIG. 2.

FIG. 5 is a longitudinal sectional view taken on the line V-V of FIG. 3.

FIG. 6 is a side elevational view, partly diagrammatic, of a second embodiment of the invention.

FIG. 7 is a side elevational view, partly diagrammatic, showing still another embodiment of the invention.

FIG. 7a is a top fragmentary view of a portion of the structure shown in FIG. 7.

FIG. 8 discloses a final modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment for the microfinishing of crankshafts is shown in FIGS. 1 to 5. A crankshaft 3 having crankpin 2 is shown diagrammatically, this crankshaft being mounted in a well-known manner, not shown, in a lathe or like rotating device which turns the crankshaft about a fixed axis of rotation. The apparatus 4 of the present invention is adapted to follow continuously a circular movement of the crankpin 2 about the axial center of bearing pin 3 of the crankshaft. On a stationary frame F, the details of which do not form a part of the invention, is mounted a support 5 which carries a parallel guide linkage. This linkage comprises two sets of parallel rails 6 and 7, respectively. The parallel rails 6 are pivoted at 8 and 9 on the frame 5 and at 10 and 11 on an intermediate plate 12, while parallel rails 7 are pivoted at 13 ant 14 on the intermediate plate 12 and at 15 and 16 on a holding plate 17. A microfinishing head or appliance carrier 18 is mounted on the holding plate 17. Thus, the microfinishing head is guided by the parallel guide linkage in a circular path with crankpin 2 about bearing pin 3 in such a way that the transverse working axis of the microfinishing head and the axis of rotation of the crankshaft always remain parallel one to the other. The pivotal joints of rails 6 and 7 are preferably guided by ball bearings.

The microfinishing head 18 serves to support and house the

superfinishing devices

19 and 20 with their

transport slides

21 and 22. The superfinishing head consists of

end plates

23 and 24, which are connected together by elon gated spacing rods 25. The support and guidance of the microfinishing head 18 on the crankpin 2 to be ground is provided by rollers 26 and 27 journaled in suitable bearings. These rollers are supported only at their ends, and engage the curved surface of the crankpin 2.

Transport slides 21 and 22 support the

superfinishing devices

19 and 20 and give these devices a gradual advance along or transverse of the length of the crankpin 2. The advance of the transport slides is provided by a stepping mechanism 28 (FIGS. 4 and 5) incorporated in each

transport slide

21 or 22. This stepping mechanism is preferably pneumatically operated.

Each transport slide is guided on two

hardened guide rods

29 and 30, and is provided with

suitable bearings

31 and 32. The stepping mechanism 28 moves the

transport rods

29 and 30, and is provided with suitable barings 31 slide by means of a nut 33, set in each slide, which is threadedly engaged with a threaded spindle 34, attached between the

side plates

23 and 24 of the superfinishing head. A cam or toothed wheel 35 is keyed to the nut 33, so that rotation of the toothed wheel will cause rotation of the nut. Each transport slide has pitsons 38 and 39 movable in

cylinders

36 and 37, respectively. These cylinders are preferably operated pneumatically. The pistons are attached to

piston rods

40 and 41 respectively and these carry ratchets 43 and 44 respectively. Each ratchet is biased inwardly by a spring 42. These ratchets 43 and 44 have outer projections which engage the spaces between the teeth 35a of the toothed wheel 35. The piston cylinder unit 36-38 serves to move toothed wheel 35 and the nut 33 in one direction of rotation, while the piston cylinder unit 37-39 serves to move wheel 35 in the opposite direction. When the ratchet 43 is engaged, the ratchet 44 is retracted, as shown in FIG. 4. Reversal of the direction of the transport slide takes place at the end position of the transport slide by selective pneumatic activation of one or the other of the two cylinders. Nut 33 is provided with ball bearings 47. The number of steps 4 permitted in the stepping device is related to the revolutions per minute of the lathe. The number of switching steps is dependent upon the diameter of the crankpin to be ground.

The

superfinishing devices

19 and 20, which are well known and the details of which are not a part of the present invention, hang on the transport slides 21 and 22, respectively. The tools on the

superfinishing devices

19 and 20 may be advanced toward or withdrawn from the work pneumatically by manually operated control rods, not shown. The surface pressure of the tools on the work may be regulated by a pressure-relief valve, these details not being part of the invention herein described and claimed.

As the crankpin 2 describes a circular path about the axis 3 of the crankshaft, the superfinishing head is supported by rollers 26 and 27 on the whirling and rotating crankpin 2. The parallel linkage maintains the axis of the superfinishing head parallel to the axis of the crankshaft 3. The holding plate 17 accurately positions the microfinishing head as the transport slides 21 and 22 move the tools along the work.

In the embodiment in FIG. 6, the parallel linkage is replaced by a guide arm rod 50 which supports the microfinishing head 48 and the microgrinding device 49. The arm 50 is made up of

sections

51 and 52 which are pivotally joined together at 53. The microfinishing head 48 is attached to the free end of the forward section 51. The microfinishing head is guided and supported on the crankpin 2 by means of the fork 54 and projecting arm 55, which carry

rollers

56 and 57, respectively. The guide arm section 52 is pivotally attached at 59 to the frame 60, which, in turn, is carried by the cross-slide 61, the latter forming no part of the invention. The crankpin is sup ported at its bearing pins 3 in the block 62 which has adjustable supporting parts 63. The guide arm 50, when the microfinishing device is not in actual use on a crankpin 2, may 'be supported by a fluid operated ram 64. Similarly, the guide arm section 51 is held in stopped position by means of a bolt 0r pin 65. When the device is used, the bolt connection 66 for the ram 64 and the bolt or pin 65 should be released. A conduit 67 shown only in fragmentary manner serves for conducting a power supply to the microfinishing head.

FIG. 7 shows a further embodiment of the device in which the support for the microfinishing head 69 consists of a rod 68. A microgrinding device 70 is carried by the microfinishing head, and likewise a guide part 71 provided with rollers 72. The inner end of rod 68 is pivotally attached as at 73 on slide elements 74 which move along the slide tracks 75 of a support 76. The slide tracks 75 are perpendicular to the axis of rotation of the crankshaft 3. Rod 68 may, if desired, be formed of telescopic sections. The slides 74, as shown in FIG. 7a, are spaced apart but are connected together by the pin or bolt 73, so that the rod 68 may swing freely between the said; slide elements.

In the embodiment of FIG. 8, a telescopic rod 77 is provided which is pivoted at 77a to a stationary base B. On the outer end of the telescopic rod 77, a microfinishing head 78 is pivotally supported as at 79. The microfinishing head 78 consists of at least two separable parts which when joined embrace the crankpin 2. The grinding stones 80 are radially directed and biased toward the crankpin 2 by the springs 81.

What is claimed is:

1. Apparatus for microfinishing a crankpin of a crankshaft as said crankshaft is rotated about its axis and said crankpin moves in a circular path about said crankshaft, comprising microfinishing tool means for engagement with the surface of said crankpin and means to support said microfinishing too], said support means comprising a stationary frame member adjacent said crankshaft, at least two sets of parallel links, an intermediate connecting means, and a tool head, one end of the first set of parallel links being pivotally connected to said frame, one end of the second set of parallel links being pivotally connected to said tool head means, said microfinishing tool means being secured to said tool head means, and the opposite ends of both said first and second sets of parallel links being pivotally connected to an intermediate con necting means, whereby said microfinishing tool means is free to move with respect to said crankpin as it rotates about said crankshaft to provide a substantially uniform speed between said crankpin surface and said microfinishing tool means.

2. Apparatus for microfinishing a crankpin of a crankshaft as said crankshaft is rotated about its axis and said crankpin moves in a circular path about said crankshaft, comprising microfinishing tool means for engagement with the surface of said crankpin and means to support said microfinishing tool, said support means including means to move said tool head means with respect to said crankpin as it rotates about said crankshaft to provide a substantially uniform feed between said crankpin surface and said microfinishing tool means and means to provide reciprocal movement to said microfinishing tool means in a path parallel to said crankshaft axis along said crankpin surface, said reciprocal movement providing means including a pair of spaced end plates, parallel guide rods connecting said plates, a transport slide guided by said rods and carrying said microfinishing tool means thereon, and means for controlling movement of said transport slide along said rods.

3. An apparatus as defined in claim 1 wherein said tool head means include roller members mounted thereon to engage said crankpin surface.

4. An apparatus as defined in claim 3 wherein said tool head means includes a U-shaped frame providing leg working members which straddle said crankpin,

said roller members being located adjacent the bight of said U-shaped frame.

5. An apparatus as degned in claim 1 wherein said means for controlling movement of said transport slide comprises a step-by-step actuator means.

6. An apparatus as defined in claim 5 wherein said actuator means includes a threaded rod extending between said end plates, nut means on said transport slide in threaded engagement with said rod, and ratchet means for step-by-step rotation of said nut means. 7. An apparatus as defined in claim 5 wherein said actuator means includes means to reverse said transport slide when it reaches each end of a desired path of movement.

8. An apparatus as defined in claim 1 wherein said means for controlling movement of said slide comprises a threaded rod extending between said end plates, a nut means on said transport slide in threaded engagement with said rods, ratchet means for step-by-step rotation of said nut in either direction of rotation and control means for actuating the ratchet means in the selected direction of rotation.

References Cited UNITED STATES PATENTS LESTER M. SWINGLE, Primary Examiner