US2200173A - Lapping machine - Google Patents

Description

May/7,1940. H. s. INDGE A2,200,173

LAPPING MACHINE Filed 061'.. 30. 1937 HERBERT SIA/DGE Patented May 7, 1940 UNITED STATES PATENT OFFICE LAPPING MACHINE Application October 30, 1937, Serial N0. 171,931

8 Claims.

The invention relates to lapping machines, and

with regard to its more specific features to a lapcylinder. Another object of the invention is to provide an attachment whereby shafts can be quickly lapped. Another object of the invention is to provide an apparatus and method for the efficient lapping of cylindrical bodies. Another object of the invention is to provide a high speed reciprocating mechanism for the lapping of metal parts involving a minimum of vibration or stresses set up'by inertia. Other objects will be y in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the several steps and relation and order of each of said steps to one or more of the others thereof, all as will be illustratively described herein, and the scope of the application of which will be indicated `1n the following claims.

In the accompanyingt drawing in which is illustrated one of many possible embodiments of the mechanical features of -this invention,

Figure 1 is a front elevation of a grinding machine having the lapping attachment incorporated thereon,

Figure 2 is an enlarged front elevation of the lapping attachment showing the wheels and mounting in axial section, and

Figure 3 is a side elevation on the same scale as Figure 2 of the lapping attachment and its mounting on the Wheel head, certain spindles being shown in section.

I provide a plain cylindrical shaft grinder of any preferred or desired form. Merely for purposes of illustration, I show in Figure 1 a cylindrical grinder comprising a base I0 supporting on the usual ways for longitudinal reciprocation a tableA or carriage II Which carries at one end a headstock I2 and at the otherend a tailstock K I3. The headstock journals a spindle, not shown, having on one end thereof a driving face plate I4 and a head center I5. By means ofthe usual lathe dog I6, the shaft I1 to be ground is rotated from the face plate I4. The face plate I4 may be driven by an electric motor 20 having an armature shaft 2| which drives the spindle for the-face plate by means of reduction gearing in the head I2, not shown, and a' belt or chain drive inthecasing 2l.

' Tailstock I3 may be of any usual or desiredconstruction, it being broken away in Figure 1 more clearly to show the lapping attachment. Both the headstock I2 and the tailstock I3 are adjustable on slideways 25 on the table or carriage II in order that the machine may grind different sized shafts I'I.

The machine may have the usual wheel head 30, Figure 3, journalling a shaft 3I upon which is mounted a grinding wheel 32, Figure 1. In such event there is preferably provided a motor 33 driving a pulley 34 which is connected by multiple belts 35 to a pulley 36 attached to the shaft 3|.

The usual cross slideways, not shown, for the wheel head 30. are also provided whereby to move the grinding wheel 32 towards and from the Shaft I'I.

For control of the cross feed there is provided a hand wheel 40 with a micrometer adjustment device 44I and a ratchet wheel, not shown, operated by a pawl 42 which is attached to a slide 43 operated by a connecting rod 44 eccentrically attached to a disk 45. Connected to the disk 45 is a small gear, not shown, which meshesA with a rack on the end of an arm 48 which is connected at 49 to an arm 50 attached to the main reversing lever 5I which is, positioned for contact with the usual table reversing dogs or stops 52 and 53 `adjustably secured to thetable or carriage Il. The reversing lever 5I operates a mechanical reversing mechanism, not shown, to traverse the table II first in one direction and then in the other, according to the position of the lever 5I. By means of a hand lever 55, the direction of travel of `the table I I can be reversed manually. I provide furthermmanually operated mechanism for moving the table or carriage I I comprising a hand Wheel 60 mounted on a shaft 6I to which is attached a pinion gear 62 meshing with a large gear 63 to which is attached a pinion gear 64 meshing with a rack 65 attached to the under side of the table or carriage II. For the mechanism thus indicated, hydraulic driving and reversing mechanism may be substituted, if desired. For a fuller description of one form of grinding machine embodying many of the features heretofore indicated, reference may be made to the patent to C. H. Norton No. 762,838 granted June 14, 1904.

Referring now to Figure 3, on the wheel head 30 I provide an extension I0 having ways receiving a slide 1I which on its under side has a rack 12 meshing with a pinion 'I3 controlled by a hand wheel 'I4 whereby the slide' II may be moved parallel to the cross slide of the machine. I provide a screw 16 controlled by a hand wheel 11 for locking the slide "II in the desired position of adjustment. The slide 1| supports the lapping attachment which is more particularly the subject matter of this invention. As shown in Figures 2 and 3, an electric motor 80'of any usual or preferred kind is attached to an angle plate 8| which in turn is secured to the slide 1|. The motor has an armature shaft 82 on the front of which is located a face plate 83 with a vslot 84 in which is adjustably fastened a stud 85 to which is connected a link 86 secured in place by means of a nut 81. The other end of the link 88 is connected by a pin 88 to levers 89 pivoted on a pin 90 secured to a block 9| attached b y means of screw bolts 92 to the angle bracket 8|. As shown in Figure 3, an upper block 94 and a lower block 95 are held against the angle bracket 8| by means of clamping plates 96 and 91 respectively which are held in position by bolts 98 and 99. On the under side of the block 94 is a V groove |00 and on the upper side of the block 95 is a V groove |00. On each of the upper and lower sides of the block 9| is a V groove |00.

Still referring to Figures 2 and 3, I provide a pair of slides |0| and |02 which have V grooves |03 on their upper and lower surfaces. balls |04 t between the respective grooves4 |00 and |03, as shown in Figure 3. By means of pins |05 and |06 vthe slides |0| and |02 are connected to the levers 89. Y

It will be seen that as the armature shaft 82 of the motor 80 rotates, the levers 89 will be oscillated and this action will oscillate the slides '|0I and |02. The amplitude of oscillation is such that the slight looseness in the connection at the pins |05 and |06 will take care of the angular movement of the lever 89 and therefore the slides |0| and I 02 are given a true reciprocating motion. The link 86, the lever 89 and the slides |0| are of skeleton construction as shown, having holes therein clearly illustrated in Figure 2 to remove as much weight as possible. I have found that it is possible effectively to reciprocate the slides |0| and |02 twelve hundred complete reciprocations a minute with an amplitude of about a quarter of an inch. Furthermore, this reciprocation takes place without excessive vibration of the entire mechanism supported on the slide 1|, since the slides |0| and 02 are always moving oppositely. Friction is reduced to a minimumby means of the bearing balls |04 and inertia is reduced toa minimum by removing as much metal as possible from the various parts, as already pointed out.

Still referring to Figure 2, extending from the left hand end of the slides |0| and |02 respectively are integral spindles ||0 upon which are mounted anged sleeves having anges H2 and an interposed washer I3 abutting the shoulders |09 which comprise the ends of the slides |0| and |02. 'I'he left hand ends of the sleeves are threaded and by means of nuts H4 engaging these threaded portions abrasive wheels H5 are secured upon the sleeves |I| to the spindles ||0 having reduced threaded portions ||8 upon Which are nuts ||1 securing the sleeves Il in place. The spindles |I0 have a reduced diame ter cylindrical portion |20 extending from the left hand end thereof upon which 4are mounted cups 2| keyed to the, portions |20. The extreme left hand ends of the spindles H0 are threaded and nuts |22 hold the cups on the portions |20. Inside of the cups |2| are springs |23 exerting vtheir pressure against the cups at one end land against washers |24 at the other end, which washers engage the nuts I4.

Bearing It will thus be seen that the abrasive wheels H5 are thrust to the right by the springs |23 and the thrust is taken .by the aforesaid shoulders |09.` 'I'his constitutes friction means preventing free rotation of the abrasive wheels ||5.

The abrasive wheels ||5 may be made of any suitable abrasive such as fused aluminaor silicon carbide bonded with any suitable bond such as any one of the clay or resinous bonds, rubber,` or any other type. Furthermore for some purposes diamond abrasive may be used. I have found that an excellent finish may be achieved upon a shaft l1 Iby rapidly reciprocating the wheels ||5 which are held from free rotation as described. 'I'his produces a lapping action upon the work piece which peens the grooves produced by grinding. The cups and springs may be termedbraking means to restrain the rotation of the wheels ||5.

In the operation ofthe machine, the operator may rst advance the lcross slide and grind the shaft l1 in the usual manner. At this time the slide 1| will be back so that the abrasive wheels as .by means of the hand Wheel 60, to Ibring the abrasive wheels H5 opposite the portion of the shaft |1 which was ground. The operator then turns the hand Wheel 14 to adjust the Wheels I I5 into contact with the shaft. In certain embodiments of the invention, the wheels I5 may be 4made of cast iron or the like and loose abrasive powder may be used to perform the lapping operation. Forthe lapping a rm contact between the abrasive wheels land the work piece is preferred but not such a pressure as will materially slow down the motor 80. The motor 80 is then energized and operated at an' angular velocity of from six hundred to eighteen hundred R. P. M.

which causes the wheels ||5 to reciprocate at from six to eighteen hundred times a minute, with an amplitude' of any amount up to threeeighths of an inch. It should be understood that so far as certain features of the invention are concerned, other rates of recipro'cation at other amplitudes may be employed. During the lapping operation, the work piece |1 is rotating in the usual manner, which tends to rotate the wheels H5, but the slight slippage due to the friction against the wheels I I5 materially assists in the lapping action.

It will vthus Ibe seen that there has been provided -by this invention an apparatus in which 1. A grinding-machine comprising a base, a

table or carriage mounted on said Ibase, a headstock and tailstockrmounted on said carriage, a cross slide, a second slide" mounted on said cross slide, and a lapping attachment on said second slide comprising a pair of additional slides mounted to reciprocate, means to reciprocate said last named slides, anda small grinding wheel mounted on each of said last named slides.

2. A highI speed lapping attachment comprising a pair of abrasive wheels, spindles mounting said abrasive wheels close together and in parallel relation, said abrasive wheels being free to rotate on said spindles, means retading the rotaweight slide, a spindle on said slide, a slideway supporting said slide, a grinding wheel mounted to revolve on said spindle, means retarding the rotation of said grinding wheel, and means to reciprocate said slide rapidly.

4. In apparatus of the class described, a bracket, an electric motor mounted on said bracket, a

plate mounted on the armature of said motor, a 'pin radially adjustable on said plate, a link mounted on lsaid pin, a lever to which said link is connected, a pivot pin on the bracket for the lever, a pair of pins at equal distances above and below said last named pin, a pair of slides mounted in parallel relation, each connected to one of said last named pins, abrasive wheels in coaidal relation mounted on said slides, and,

means to retardthe revolutions of said abrasive wheels.

5. In a grinding machine, means to hold and rotate a generally cylindrical work piece, a grinding wheel to grind said work piece, a pair of lapping wheels to lap said work piece mounted on axes parallel to each other and parallel to the grinding Wheel, means to reciprocate said lapping wheels oppositely, and means retarding rotation of said lapping wheels, whereby al1 portions of the work piece may be lapped to the same extent by grinding and lapping the work piece without removing it from the holding and rotating means.

6. In a machine of the class described, a pair of grinding Wheels, means mounting said grinding Wheels on parallel axes', means to reciprocate the grinding wheels axially and oppositely, and means restraining rotation of the grinding Wheels, whereby to achieve a ilne lapping action on a work piece.

'7. An attachment comprising a pair of parallel slideways, a pair of slides mounted in said slideways, bearing balls interposed between the slides and the slideways, reciprocating means for reciprocating the slides oppositely, an abrasive wheel rotatably mounted on each slide, and means to restrain the rotation of each abrasive wheel, whereby to achieve a ne lapping action on a Work piece, the lapping lines .being broken up -by the reciprocation.

8. Method of lapping a work piece which is a surface of revolution which comprises rapidly reciprocating an abrasive Iwheel in contact with the Work piece, the line of recprocation being parallel to the axis of the work piece, and the abrasive wheel .being rotated by its contact with the work piece and retarded from free rotation, thus producing a dragging actionA on the work piece to effect a fine lapping, the reciprocation breaking up the lapping lines. A

HERBERT S. INDGE.

Images