US2248502A - Lapping machine - Google Patents

Description

M 1941. H. s. INDGE ETA'L LAPPING MACHINE Filed Feb. 28, 1939 S Sheets-Sheet 2 1:21-22 27 2" d: wemo e C60a E Q H f? 1941- I H. s. INDGE ETAL 2,248,502v

LAPPING MACHINE Filed Feb. 28, 1939 3 Sheets-Sheet 3 Wdace Fm W5; C em L l Gnomeg Patented July 8, 1941 'Herbert S. Indge, Westboro, and Wallace H.

Wood, Worcester, Mass, assignors to Norton Company, Worcester;-Mass., a corporation of Massachusetts Application February 28, 1939, Serial No. 258,916

8 Claims.

and more particularly to a machine usedfor lap: ping the surface of a cylindrical work piece.

The requirements of the machine tool industry are such that after a cylindrical work piece, such as a shaft, has been ground by.a standard cylindrical grinding operation, it is often necessary toprovide the workwith a smoother finish by treatment in a separate lapping machine. Some types of work which are large or awkward to handle are not readily lappedby the machines of standard equipment. It, moreover, is desirable to lap such work pieces while still mounted on the cylindrical grinding machine where they have been ground to shape.

It is accordingly a primary object of this invention to provide an attachment for a grinding machine which will serve for lappinga cylindrical work piece while still mounted in grinding position. p

A further object is to provide a lapping device capable of use with various types of machines adapted for rotating a cylindrical work piece which will lap the work surface properly to so move a lapping stick as to, give a satisfactory finish to a work piece. Other objects will be apparent in the following disclosure.

In accordance with this invention,. we have provided a device for lapping a rotating cylin-,- drical work piece which comprises a lapping stick so supported and controlled in its motion that it will move in a rectilinear path across the surface of a work piece to be lapped.

A further object of the invention is to provide a construction which will reciprocate a lapping stick parallel with the work axis and in a rectilinear path and which may be readily controlled and operated.

Referring to the drawings which illustrate a preferred embodiment of this invention:

Fig. 1 is a front elevation, partly broken away, of a grinding machine carrying this lapping device as an attachment thereon;

Fig. 2 is a front elevation, partly in section, looking in the direction of the arrow 2 of Fig. 1;

Fig. 3 is a section on the line 33of Fig. 2;

Fig. 4 is a fragmentary detailon the line 4--4 of Fig. 2; v V

Fig. 5 is an enlarged fragmentary view of the lapping head and associated parts; i

Fig. 6 is a detail of the lapping stick mount looking in the direction of the arrow 6 of Fig. 5;

Fig- 7 is a plan view, partly in section, looking in the direction of the arorw l in Fig. 6; and

Fig. 8 is an enlarged sectional detail on the line 8-8 of Fig. 7., p I H p This device is illustrated in the drawings as an attachment for a cylindrical grinding machine, but the lapping mechanism may be built into a separate or other types of machine and used independently of the grinding operation. The work piece It shown in the drawings as mounted on the centers II and [2 of a standard grinding machine may be rotated by suitable mechanism including a driving plate I3 on a head stock I4, where it is normally intended to be ground by means of a grinding wheel I suitably mounted on a wheel slide I6 and arranged,

as shown in various constructions of the prior art, such as in the prior patent to Wood No. 2,071,677. After the work has been groundto a required size, the grinding wheel is withdrawn and the lapping head of the present invention is brought into play. Y The lapping mechanism comprises in general two lapping sticks which'are so mounted that they may be reciprocated in a rectilinear path or parallel with the axis of the rotating cylindrical work piece. As shown in Figs. 5 to 8, the lapping sticks are suitably mounted on a block 22 and. held in place by cement or by clamping blocks 23. The block 22 is provided with two spaced ears 24 which are pivotally suspended on two pins 25 projecting laterally from a block 26. This block is in turn provided with two outwardly extending pins 27 which are pivotally mounted in two spaced arms 28. The two sets of pivots thus enable the lapping sticks to rock in all directions and thus line up properly with the work during the lapping operation. A set of springs 30 are mounted in holes in the plate 22 and block 26 and held in place by a set screw 3|. The arms 28 are removably mounted on the ends of a cross bolt 32 and locked in place there} on by latches 33 on the arms engaging grooves in the ends of the pin 32. The pin 32 passes through two spaced members 36 forming the reciprocating and rocking frame of the lapping head; and the arms 28 engage and are held in place by shoulder 31 on the frame.

The frame 36 is pivotally mounted on two sliding blocks 38 (Fig. 3) by means of a pin 39 passing freely through the two spaced frame members 36 and the blocks 38. These blocks are slidably mounted in short slideways 40 cut in the lugs 4| projecting inwardly from the housing 42 of the lapping head. i

The frame 42 (Fig. 3) slides on a dovetailed slideway 45 which projects laterally from a piston casing or cylinder 46 and the latter is in turn connected with an elongated plate 48, which is provided with slots 49 through which clamping bolts 59 are passed. These bolts tap into a further plate 52 which is attached to a member 53 integral with the slide 54 (Fig. l) which in turnis mounted on a dovetailed slideway 55 and held against ready movement by a friction key 56. The slideway 55 is suitably secured on the housing of the grinding wheel I 5. The slide 54 may be adjusted by means of a gear 58 pivotally mounted on the wheel housing meshing with a rack bar 59 on the slide 54. The gear is turned by a hand wheel 69 and thus serves to adjust the lapping sticks towards and from the work piece. The other adjustment may be made manually by sliding the plate 48 relative to the plate 52 and then securing the parts in position by tightening up on the bolt and nut 59. I

A primary feature of this invention involves so moving the lapping sticks 20 that they will move in contact with the work under substantially a uniform pressure. To this end, the frame 36 is rockedpivotally and moved up and down so that the lapping sticks will move along the work surface in a straight line path. The frame may be rocked by suitable mechanism, such as an electric motor 6| or an hydraulic motor, suitably controlled by manually operated control devices, which is mounted on the top of the cross head 12. On the end of the armature shaft is a plate 62 having a block 63 adjustably positioned in a slot therein and pivotally attached to the connecting arm 64 which in turn connects with the top 65 of the rocking frame 36. A screw 66 suitably mounted on the plate 62 serves to position the pivotal block 63 in any desired eccentricity relative to the axis of the motor armature. Thus the throw or the degree of rocking of frame 36 and the sticks on the bottom thereof may be widely adjusted.

In order to provide the rectilinear motion, a cam 10 is mounted on the underside of the cross head I2 which carries the motor; and the cam face 13 of this cam is so shaped that as the roller 14, pivotally mounted between the frame members 36, rocks back and forth, it will cause the frame to move up and down. The cam roller is mounted on a pin secured in two inwardly projecting hubs 16 on the frame 36. The roller is held up against the underside of the cam by means of a spring 18 secured to an adjustable screw 80 mounted on a suitable stationary portion of the housing 42 and connected at its other end tot the cross pivot 39. The cam face 13 is accurately shaped so that as the frame swings, the under faces of the abrasive sticks will be held in linear contact with the work and will move in a given plane. Hence, they will be pressed against the work with a uniform pressure throughout their entire reciprocatory movement. The length of travel may be short and only enough to provide a satisfactory break-up motion and cause the abrasive grains to cut ina crisscross fashion on the rotating work surface.

The cross head 72 is shaped, as indicated in Fig. 4, to provide two cut-out portions separated by a tongue 8| which supports the cam ill. The cut-out slots provide two surfaces 82 and 8.3 which serve as slideways for plane sides formed on the rocking frame 36, so that the top of the frame may be guided as it rocks and slides up and down. The slide blocks 36 at the lower end of the frame are held from lateral movement bytheir guide channels 40, and the frame is therefore so held that it may rock while its pivotal supporting pin 39 moves freely vertically.

The cross head 12, which supports the motor and carries the housing and sliding frame 36, is so mounted that it may be raised and lowered by suitable mechanism. One form as illustrated in Fig. 1 comprises a piston chamber in the cylinder 46 within which slides a piston rod 9| having a piston 92 thereon. The piston rod passes through the cylinder head 93 and is connected at its upper end to the cross head 12 and thus serves to move the same. Oil or fluid may be admitted under pressure to the opposite ends of the piston chamber by means of the pipes 94 and 95 and controlled by a suitable reversing valve comprising a casing 96 (Fig. 1) having two valves 91 and 98 therein mounted on a stem 99. A hand lever I00 is connected to the stem and suitably arranged to move the valves into either of two desired positions. Oil admitted through pipe I02 enters the space between pistons 91 and 98 and then passes. through pipe 94 to move the piston 92 downwardly so that the lapping ticks will engage the work. When the valve is moved to. the other position, then oil is admitted into the pipe 95 and the lower part of the piston chamber to raise the lapping head. The oil is exhausted from either position of the piston 92 through the pipes I94.

The operation of the above described mechanism has been fully set forth above. Also, the advantages inherent in the construction will be apparent. to one skilled in the art. In particular, the mechanism is one wherein the motor for oscillating the abrasive sticks may be located at a point remote from the work and where there is ample room therefor. Also, a pivotal mount for the abrasive sticks provides a simple mechanical element for transmitting motion from the remote motor to the lapping element; hence the swinging frame 36 is especially useful in a machine of this type.

It will now be appreciated that many modifications may be made in the above described construction, and that one may substitute equivalent mechanisms for those illustrated. For example, the motor employed for reciprocating the abrasive sticks may. be operated hydraulically and constructed and arrangedas shown in the companion application to which reference is made herein. Such a motor may be controlled by suitable valve mechanism which is coordinated with the other parts of the machine. It will also be appreciated that one may substitute for the hydraulic lifting device, employed to move the abrasive sticks towards and from the work, any other type of mechanism whether operated by hand or by power which will serve this purpose. The hydraulic mechanism as shown in the drawings is preferred because of its simplicity of structure and the ease of operation and control. It will, therefore, be appreciated that the above description is to be considered as illustrating the principles of the invention and a preferred embodiment, but not as limiting the scope of the claims appended hereto.

The mechanism which controls and coordinates the movement of a grinding wheel for sizing the work with the operation of the lapping device for finishing the work surface is described and claimed in the copending application of Indge and Hulbert Serial No. 260,676 filed on March 9, 1939.

We claim:

1. A lapping machine comprising a support for rotating a cylindrical work piece, a lapping abrasive stick, a rocking support for the abrasive stick and means for moving said support as it rocks so as to cause the abrasive stick to travel in a rectilinear path and maintain contact with the rotating work.

2. A lapping machine comprising means for rotating a cylindrical work piece about its axis, an abrasive stick, a pivotal support therefor, means for rocking the abrasive stick about its support and means including a cam for moving the pivotal support during the rocking movement so that the operative face of the abrasive stick travels in a plane and maintains contact with the work surface.

3. A lapping machine comprising means for supporting and rotating a cylindrical work piece about its axis, a lapping stick, a swinging frame carrying said stick, a motor connected to swing the frame, means including a cam arranged to move the frame as it swings, so that the operative face of the abrasive stick travels in a plane, and. means for moving the frame towards or from the work piece.

4. A lapping machine comprising a swinging frame, a lapping stick resiliently and pivotally supported on the frame, a sliding support for this frame, a motor for swinging the frame and means for moving the frame and its support so that as the frame swings the abrasive stick may travel substantially parallel with the work axis and maintain contact with the Work under a substantially uniform pressure throughout its stroke.

5. A lapping machine comprising a support for rotating a cylindrical work piece, a lapping abrasive stick, a rocking support for the abrasive stick, means for moving said support as it rocks so as to cause the abrasive stick to travel in a rectilinear path and maintain contact with the rotating work and mechanism for moving the stick towards and from contact with the work.

6. A lapping machine comprising means for rotating about its axis a cylindrical work piece, a non-rotatable abrasive stick, a rocking frame supporting the stick for a swinging movement in an axial plane of the work and about an axis spaced from the work axis, a slide carrying the rocking frame, means for rocking the frame and means for moving its supporting slide so that the operative face of the abrasive stick moves in a rectilinear path in contact with the rotating work and parallel with the work axis.

7. A lapping machine comprising means for supporting and rotating a cylindrical work piece about its axis, a lapping stick, a pivoted rocking support for the stick, means for rocking the support, means for moving the support as it rocks and causing the operative face of the lapping stick to lap the work and travel in a rectilinear path parallel with the work axis, and means for varying the extent of reciprocation of the lapping stick.

8. A lapping machine comprising means for supporting and rotating a cylindrical work piece about its axis, a rocking frame, means to rock the frame in a plane of the work axis, a lapping stick movably mounted on the frame for self alignment with the work surface, pivotal bearings for the frame mounted for movement towards and from the work axis, and means including a cam arranged to move the bearings and cause the operative face of the stick to move in a rectilinear path in contact with the work and parallel with the work axis.

' HERBERT S. INDGE.

WALLACE I-I. WOOD.

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