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Crankpin lathe and tool head and work head therefor

Imported: 24 Feb '17 | Published: 06 Jan '04

Gen Ogawa, Satoru Senda

USPTO - Utility Patents

Abstract

A crankpin lath is improved in positioning a crankpin onto the axis of work spindles precisely and in a short period of time by the use of simple and low-cost mechanisms. Indexing a crankpin to be machined next onto the axis of the work spindles is initiated in the state that journals of a crankshaft are clamped on index members which are rotatably supported respectively on work spindles with the axes thereof being offset by an eccentricity of crankpins from the axis of the work spindles. First, a clutch device interposed between each of the work spindle and the index member carried thereon is brought into disengagement. Then, a pin pusher is advanced toward the axis of the work spindle as it pushes a machined crankpin of the crankshaft and is positioned to a position spaced by a predetermined distance from the axis of the work spindle while the work spindle is rotated by half an angle through which the crankshaft is to be indexed rotationally. Thereafter, the clutch device is brought into engagement to complete the indexing operation.

Description

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The foregoing and other objects and many of the attendant advantages of the present invention may readily be appreciated as the same becomes better understood by reference to the following detailed description of a preferred embodiment of the present invention when considered in connection with the accompanying drawings, wherein like reference numerals designate the same or corresponding parts throughout several views, and in which:

FIG. 1 is a plan view of a first embodiment of a crankpin lathe according to the present invention;

FIG. 2 is a longitudinal sectional view of a work head

FIG. 3 is an explanatory view showing the state that a crankshaft grasped by chucks on left and right work spindles is machined with a cutting tool;

FIG. 4 is a section of an indexing mechanism incorporated in a tool head;

FIG. 5 is a side view of an index body of the tool head, showing the state of cutting tools and a pin pusher being mounted on the index member;

FIG. 6 is a fragmentary front view of the index member;

FIG. 7 is a fragmentary front view of the index member, showing a cutting tool attached in a manner different from that shown in FIG. 6;

FIGS.

8(

a) and

8(

b) are explanatory views showing the turning operations with various cutting tools; and

FIGS.

9(

a) to

9(

c) are explanatory views showing the operation for rotationally indexing crankpins.

Claims

1. A crankpin lathe wherein work heads are mounted on a bed for supporting work spindles driven by work spindle drive devices, respectively; said work spindles are provided for clamping journals of a crankshaft thereon with a crankpin being on the rotational axis of said work spindles; and a tool head for attaching cutting tools is mounted on said bed to be moved by a tool head feed device relative to said work heads for turning said crankpin; said crankpin lathe further comprising: index members supported respectively on said work spindles for rotation about an axis which is parallel with, and offset by an eccentricity of said crankpins, from the axis of said work spindles; clutch mechanisms each interposed between said index member and said work spindle for restraining the relative rotation between said index member and said work spindle when brought into engagement, but for permitting the relative rotation when released from engagement; clamp devices provided respectively on said work spindles for removably clamping said journals; a pin pusher mounted on said bed and movable by a pin pusher feed device toward the axis of said work spindles for causing said pin pusher to push said crankpin; and a control device for positioning the machined crankpin to a position spaced by a predetermined distance from the axis of said work spindles by pushing with said pin pusher said machined crankpin with said clutch device being made disengagement and for rotating said work spindles by half an angle through which said crankshaft is to be indexed rotationally relative to said work spindles so as to position a crankpin to be machined next onto the axis of said work spindles before bringing said clutch device into engagement.

2. A crankpin lathe as set forth in claim 1, wherein said control device comprises a numerical controller; wherein said work spindle drive devices, said tool head feed device and said pin pusher feed device include servomotors each of which is controllable in accordance with commands from said numerical controller; and wherein said numerical controller is operable for bringing said clutch device into disengagement, then simultaneously controlling said pin pusher feed device and said work spindle drive devices so as to position said machined crankpin to said position spaced by a predetermined distance from the axis of said work spindles by pushing said machine crankpin with said pin pusher and so as to position a crankpin to be machined next onto the axis of said work spindles by rotating said work spindles by half said angle through which said crankshaft is to be indexed rotationally relative to said work spindles; and bringing said clutch device into engagement.

3. A crankpin lathe as set forth in claim 1, wherein said pin pusher is mounted on said tool head; and wherein said tool head feed device operates as said pin pusher feed device.

4. A crankpin lathe as set forth in claim 1, wherein said pin pusher is mounted on said tool head; wherein said tool head feed device operates as said pin pusher feed device; and wherein said tool head is further provided thereon with an extension device for positioning said pin pusher selectively to an operating position where said pin pusher extends toward said crankpin positioned on the axis of said work spindles and a retracted position to which said pin pusher is moved back from said operating position.

5. A crankpin lathe as set forth in claim 3, wherein a plate-like index body is mounted on said tool head rotationally indexably about an axis parallel with the axis of said work spindles; wherein said cutting tools and said pin pusher are attached to the circumferential portion of said index body; and wherein an index device is provided on said tool head for rotationally indexing said index body so as to selectively index said cutting tools and said pin pusher to a position where they face with said crankpin positioned on the axis of said work spindles.

6. A crankpin lathe wherein a work head is mounted on a bed for supporting a work spindle driven by a work spindle drive device; said work spindle is provided for clamping a journal of a crankshaft thereon with a crankpin being positioned on the rotational axis of said work spindle; and a tool head for attaching at least one cutting tool is mounted on said bed to be moved by a tool head feed device relative to said work head for turning said crankpin; said crankpin lathe further comprising: an index member supported on said work spindle for rotation about an axis which is parallel with, and offset by an eccentricity of said crankpin, from the axis of said work spindle; a clutch mechanism interposed between said index member and said work spindle for restraining the relative rotation between said index member and said work spindle when brought into engagement, but for permitting the relative rotation when released from engagement; a clamp device provided on said work spindle for removably clamping said journal; a pin pusher mounted on said bed and movable by a pin pusher feed device toward the axis of said work spindle for causing said pin pusher to push said crankpin; and a control device for positioning the machined crankpin to a position spaced by a predetermined distance from the axis of said work spindle by pushing with said pin pusher said machined crankpin with said clutch device being made disengagement and for rotating said work spindle by half an angle through which said crankshaft is to be indexed rotationally relative to said work spindle so as to position a crankpin to be machined next onto the axis of said work spindle before bringing said clutch device into engagement.

7. A tool head for a crankpin lathe wherein a crankshaft is clamped on at least one work spindle rotatably carried on a work head, with a crankpin to be machined next being in axial alignment with the axis of the work spindle so that said crankpin is machined with a cutting tool moved radially thereof while being rotated about the axis of said work spindle; said tool head comprising a tool head body mounted to be movable in a first direction parallel with the axis of said work spindle and a second direction transverse to the axis of said work spindle; first and second feed devices drivingly connected with said tool head body for moving the same respectively in said first and second directions, a plate-like index body carried on said tool head body and rotationally indexable about an axis parallel with the axis of said work spindle, said index body having a thickness larger than the distance between a pair of shoulder surfaces formed on axial opposite ends of said crankpin to be machined; an index drive device provided on the tool head body for rotationally indexing said index body; and a plurality of tool attaching portions arranged on the circumferential portion of said index body for respectively attaching cutting tools thereon and formed as locally thin portions whose width is narrower than said distance between said pair of shoulders, so that each of said locally thin portions is able to advance between said pair of said shoulder surfaces without interfering with the same.

8. A tool head as set forth in claim 7, wherein some of said locally thin portions are surrounded by a thick wall except for the circumferential surface of said index body.

9. A work head for a crankpin lathe wherein a work spindle clamping thereon a crankshaft is rotated with a crankpin to be machined being in axial alignment with the axis of said work spindle; said work head comprising said work spindle rotatably supported in a housing thereof; a chuck body connected with one end of said work spindle; an index member mounted in said chuck body with the axis thereof being offset by an eccentricity of said crankpin from the axis of said work spindle and rotatably indexable about the axis thereof; a collect chuck co-axially received in said index member and rotatable bodily with said index member; an operating mechanism received in said work spindle and connected with said collet chuck for operating the same so as to clamp a journal of said crankshaft on said work spindle; a clutch mechanism interposed between said chuck body and said index member for selectively making the same freely rotatable or restrained from free rotation; and a servomotor for rotating said work spindle with said clutch mechanism being disengaged whereby relative rotation between said work spindle and said crankshaft is brought about thereby to rotationally index a crankpin onto the axis of said work spindle.

10. A work head as set forth in claim 9, wherein said clutch mechanism comprises first and second toothed rings coaxially arranged on the axis of said index member and secured respectively to said chuck body and said index member, each of said first and second toothed rings having an array of gear teeth on one lateral surface thereof; a third toothed ring provided in axial alignment and in face-to-face relation with the gear teethes on said first and second toothed rings; and actuation means for axially moving said third toothed ring relative to said first and second toothed rings so as to bring gearing engagement between said first and second toothed rings by way of said third toothed ring.

11. A work head as set forth in claim 10, further comprising a support member secured to said chuck body and incorporating therein said index member, said first to third toothed rings and said actuation means, said support member being adjustable in a radial direction of the axis of said work spindle; and a spacer removably interposed between said chuck body and said support member for establishing the position of said support member relative to the axis of said work spindle in the radial direction thereof whereby the position of said support member is adjusted in adaptation to another kind of crankshafts which are different from said crankshaft in the eccentricity of said crankpins.