US2150561A - Shankless bit holder and clamp - Google Patents

Description

March 14, 1939. E. REANEY 2,150,561

SHANKLESS BIT HOLDER AND CLAMP Filed March 12, less if INVENTOR- Patented Mar. 14, 1939 UNITED STATES PATENT OFFICE SHANKLESS BIT HOLDER AND CLAMP Ernest Reaney, Stratford, Conn., assignor to The 0. K. Tool Company, Inc., New York, N. Y., a corporation of New York Application Marchl 12,

Claims.

5 ofi'set relation with the longitudinal axis or coincidental therewith.

A primary aim of the invention is to render available a holder in which shankless bits may readily be inserted, adjusted laterally, or removed, and in which a firm and rigid seating of the bit is provided in any position of lateral adjustment within the range of the tool.

A further object of the invention is to obtain such firm and rigid clamping of the bit in a man-- 7 ner whereby the stresses incident to the tooling operation that normally tend to overturn the bit or knock it from its seat in the holder, are transmitted directly to integrally formed portions of the body member.

Still a further object of the invention is to attain a secure clamping of a shankless L-shaped bit byforces applied across the top of the rearwardly extending portion and in a manner whereby the overturning forces are transmitted to the body member rather than to the clamp screw or other medium that initially effected the clamping action.

A further aim of the invention is to attain a firm clamping of tool bits of the shankless type with a minimum of parts or mechanism and compactly to arrange such parts entirely behind the upstanding portion of the L-shaped bit so as not to interfere with the work or freedom of chip removal and in a manner capable of subsequent manipulation and use with relative ease.

A further aim of the invention is to attain a firm clamping of a shankless bit in a recess at the end of a holder by forces acting generally downward and rearward in a direction substantially coincident with the direction of the forces reacting from the cutting operation thus relieving the clamping instrumentalities of counterstresses and promoting a high degree of rigidity to the assembled tool. A clamp means so designed will hold the bit against its lower and rear seating surfaces and simultaneously over its upper surface which in effect abuts against a rigid portion of the holder which overlies the bit. The initial clamping is effected by moving the bit in the same general direction that it is urged during actual cutting operation by forces that simultaneously clamp the bit between upper and lower portions of the holder body. With this construction the tool bit is positively restrained from overturning 1938, Serial No. 195,472

and the initial clamping element relieved of the shocks and strains incident to normal use.

In attaining the objectives of the invention it is proposed to use a body member having strong, tough characteristics, such as a forging, and to form therein a bit socket extending crosswise its forward end. The lower surface of the socket is rearwardly and downwardly inclined, to favorrearward movement of the bit under the action of the clamp means and the tooling forces, and which terminates in an upstanding rear abutment surface coextensive in Width. A complementally shaped tool bit, inserted in the recess, may thus be adjusted laterally without restriction.

To hold the bit in place it is proposed to extend a portion of the forged body member for- Ward into overlying relation with the tail portion of the bit but spaced therefrom a distance sufficient to permit the use of an intervening rearwardly and downwardly movable clamp piece. To promote the clamping action the space between the overlying portion of the body and the tail portion of the bit is wedge shaped (in a longitudinal vertical section), the wedge being formed in part by a upwardly sloping surface of the bit and a downwardly sloping of the under surface of the overlying portion of the body, and both surfaces are located to the rear of the upstanding portion of the bit.

A wedge block is interposed between the sloping surfaces and is arranged to be pushed rearwardly and downwardly as by means of a set screw. As the wedge piece is moved rearwardly it tends to pull the tool bit in the same direction, and as it moves downwardly, it tends to push the bit in that direction, with the result that the bit is urged firmly against the bottom and rear walls of the socket and simultaneously clamped along its upper surface. By this means a shankless tool bit may be clamped firmly in its seat in the end of a holder with the assurance that the bit will not be overturned or knocked out of its socket by reason of the clamp screw or the clamp element itself being cracked, bent, or forced out of position by a sudden downward blow at the end of the tool bit. In the present construction a portion of the solid body of the holder overlies the bit and in the intervening space a wedge block is inserted which transmits such overturning forces directly to the body so that the clamping element itself is not required to withstand any force but that of compression and the clamp screw relieved of substantially all stresses.

The actuating screw engages the wedge block preferably intermediate its ends, and to provide the necessary room for the screw, the wedge block is enlarged in that region and a corresponding cavity is made in the body member to receive it. This construction has the advantage that the wedging action and consequently, the clamping action is caused to occur most strongly at the sides of the assembly where the greatest clamping force is necessary. In prior constructions where a single screw or clamp element engaged the bit at a single point near its center, the clamping was effected at a point some distance removed from the outer edges of the bit and holder, and in consequence, left those outer portions unclamped and subject to yielding. Such disadvantages are entirely eliminated by a'tool constructed in accordance with this invention wherein the bit is clamped along its outer marginal edges.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawing.

To enable others skilled in the art so fully to apprehend the underlying'features hereof that they may embody the same in the various ways contemplated by this invention, a drawing depicting a preferred typical construction has been annexed as a part of this disclosure and, in such drawing, like characters of reference denote corthereof.

Fig. 3 is a front view of the bit socket.

Fig. 4 is a side View detail of the bit clamp.

Fig. 5 is a vertical section through the clamp means. 7

Fig. 6 is a partial sectional view along lines 6- -6 of Fig. 5.

.The tool illustrated in Fig. 1 comprises an elongated body member ID having formed at its forward end a bit receiving recess I I within which a tool bit I2 is adapted to be seated and clamped. The body Ill has a portion II! underlying the tool bit, and a portion Ill overlying the tool bit, and between the two portions a wedge block I3 and the bit I2 are mounted. As shown more clearly in Figs. 2 and 4, the lower bit seating surface I4 is inclined rearwardly and terminates an upstanding abutment surface I5. Both surfaces extend crosswise the holder so that the tool bit may be inserted from either side and adjusted laterally to the right or to the left.

The tool bit I2 is generally L-shaped in character and provides an upstanding cutting portion IZ and a rearwardly extending base and tail portion I2 The upstanding portion gives body and strength and provides material for regrinding, and the base portion which has its lowerand end seating surfaces I2 and I 2 complemental to the cooperating surfaces of the bit socket, pro vides relatively wide and flat seating surfaces and a means for clamping. The'upper surface I2 of the tool bit'slopes forwardly relative to the bottom surface I2 so that the tool bit is wider at its rear end than at a point immediately adjacent the upstanding portion I2 The purpose for an enlarged end is to provide an abutment effective to resist inadvertent forward movement of the bit when clamped, and also to afford a semipositive abutment for urging the bit rearwardly anddownwardly during the manual operation of clamping the bit in its socket.

Inorder to efiect a firm clamping over relatively large areas or surfaces of the bit without risking snapping or bending of the clamping instrumentality, the portion "l of the body is formed to extend forward as to overlie the tail portion of the bit. The under surface of the overlying portion is disposed at a relatively wide, forwardly divergent, angle relative to the top surface I2 of the bit. Within the space I6 thus formed, a wedge shaped compression member I3 is inserted. The lower surface of the wedge engages the clamping surface l2 of the bit and the upper surfaces engages the sloping surface I! of the overhanging portion of the body.

The wedge member I3 is coextensive in width to the body member as shown in Fig. 3 and is provided intermediate its ends with screw clamp means -I 8. To receive the screw, the member I3 is enlarged as at I9, and a corresponding recess 20 is formed in the body to receive it. This method of construction leaves two forwardly projecting portions 2| and 22 of the body member overlying the tool bit and bit seat, and two laterally extending wedge portions 23 and 24 at opposite ends of the wedge; member, with an intermediate portion definitely interlocked and positively preventing any side slip of the wedge relative to the body. The construction is such that during the clamping action the end portions of the wedge block have a firm bearing or backing directly against portions 2| and 22 of the body. If desired, a slight clearance may be provided between the center portion I9 and recess 20, and between the clamp screw I8 and the wedge member I3 to simplify manufacture.

As illustrated in Figs. 4 and 5, the path of movement of the wedge block is in a downward and rearward direction approximating the same direction as the resultant of the tooling forces acting at the front end of the bit. By reason of the gradual enlargement of the tail portion of the tail bit, movement of the wedge downwardly and rearwardly exerts a semi-positive force on the tool bit, thus also moving it downwardly and rearwardly until clamping is attained over the surfaces I4 and I5.

As previously mentioned the upper and lower sides of the wedge block diverge at a relatively wide angle. This is necessary in order to insure the semi-positive pushing as well as pulling action in the tool bit, in elfecting clamping thereof on the three sides with due regard, of course, to the slope of the lower seating surface I4. By making the included angle on the wedge piece approximately 30 and the included angle of the tail portion of the bit approximately 10, a good clamping action is obtained.

' The included angle of the wedge piece should, however, be greater than the angle of friction but less than 90 to obtain the best results within the space limitations in that particular region of tools of this character. For example, if a very low angle is used, too great a longitudinal movement of the wedge piece is necessary to secure adequate clamping or free releasing for adjusting purposes and space limitations in that particular region in holders for tool bits of this character prohibit such large movements. Also, with a low angle diiiiculties in releasing for regrinding and readjustment purposes are encountered. If an unduly wide angle is used the objectives of a three surface clamping without the risk of bending or breaking one or more of the clamp parts incident to the act of clamping or resulting from a sudden blow at the end of the tool bit, are defeated.

It' will further be seen that with the present invention the actual clamping-force is exerted toward the outer edges of the bit, so whether the assembly be used for cutting on the right or on the left, the bit is clamped on the side nearest the cutting action and also on the side opposite where greater lever action is obtained. In this invention the disadvantages found in earlier devices in which clamping was effected at a single central point and the outer margins of the bit left unclamped and subject to springing and yielding tendencies resulting in rocking effects of the bit, have effectively been eliminated.

As is apparent from the foregoing, the strong and rigid clamping of the tool bit in the present invention, is effected in all positions of lateral adjustment within the range of the tool. And so that such lateral adjustment may be effected in unit increments of definite amounts, a series of interlocking formations are provided between the seating surfaces of the bit and holder. In Figs. 5 and 6, the formations are indicated as serrations 25 and 26 extending downward and rearward in the direction of the clamping movement of the bit. Hence, the serrations serve as a guide during the clamping action and as positive means for preventing twisting or pivoting of the bit on its seat.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various utilizations by retaining one or more of the features that, from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention, I claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of the United States:

1. A shankless tool bit and holder combining a body member having a bit receiving recess across its forward end, said recess being defined by a lower fiat bit seating surface and a rear abutment wall inclined slightly forward as to overlie a portion of the seating surface, said abutment wall being a plane surface coextensive in width with said seating surface; a shankless tool bit having a lower and a rear surface, complemental to the said surfaces defining the recess, adapted to be fitted in said recess, said bit having an upper clamp engaging surface inclined generally downward in a forward direction and extending crosswise the tool bit; a clamp element having a portion thereof engageable with said upper surface of the bit and an opposite portion engageable with the under surface of an overlying portion of the body member, said upper clamp surface of the bit and said under surface of said overlying portion of the body member being disposed at an angle of not less than 25 converging rearwardly; and means for urging said clamp element rearwardly to effect a clamping of the bit upon said seating surface and simultaneously against said rear abutment wall.

2. A shankless tool bit and holder therefor combining a body member having a bit receiving recess across its forward end, defined by a lower fiat bit seating surface terminating in an upstanding rear abutment surface; a shankless tool bit having a lower surface and a rear surface complemental to the surfaces defining the bit recess adapted to be fitted in said recess, said bitalso having an upper clamp engaging surface inclined generally downward and forward and extending crosswise the tool bit; said body also having a portion thereof overlying said recess and spaced from the top of the inserted bit; a clamp element in said space between said bit and the overlying portion of the body and having a portion thereof engageable with said upper surface of the bit and an opposite portion engageable with the under surface of the overlying portion of the body member, said upper clamp surface of the bit and said under surface of said overlying portion of the body member and the correspond-ing surfaces of said clamp element being disposed at an angle greater than the angle of friction but not exceeding 90 and converging rearwardly; and means for urging said clamp element rearwardly and downwardly to effect a clamping of the bit upon said seating surface and simultaneously against said rear abutment wall.

3. A shankless tool bit and holder therefor combining a body member having a bit receiving recess at its forward end, said recess being defined by a lower fiat bit seating surface and a rear abutment surface, said abutment surface being coextensive in width with said seating surface; a shankless L-shaped tool bit having a lower surface and a rear surface complemental to the said surfaces defining the recess adapted to be fitted in said recess, said L-shaped bit having an upper clamp engaging surface extending crosswise the tool bit disposed to the rear of the upstanding portion thereof; said body member also having a portion overlying the rear portions of said bit and bit recess with its under surface disposed at an angle to the clamp surface of the inserted bit and spaced therefrom; a clamping wedge insertable in said space and having a portion thereof engageable with said upper surface of the bit and an opposite portion engageable with the under surface of said overlying portion of the body member, said wedge thereby transmitting directly to the body member the forces incident to the tooling operation tend ing to overturn said bit; interfitting means between said bit and body member affording lateral adjustment of the bit relative thereto in positive unit increments; and means for urging said clamping wedge rearwardly to effect a clamping of the bit upon said seating surface and simultaneously against said rear abutment surface.

4. A shankless tool bit and holder combining a body member having a bit receiving recess extending across its forward end, a shankless tool bit adapted to be fitted in said recess and laterally adjusted therein, saidbit having an upper clamp engaging surface extending crosswise the tool bit; said body also having two projecting portions overlying said recess and spaced from the said upper surface of the inserted bit; a clamp element in said space having a portion thereof engageable with said upper surface of the bit and two opposite portions respectively engageable with the under surface of the projecting portions of the body member, said upper clamp surface of the bit and said under surfaces of said projecting portions of the body member being disposed at an angle of less than 90 and converging rearwardly; means for urging said clamp element rearwardly to effect a clamping of the bit upon said seating surface and simultaneously against said rear abutment wall; and interlocking means between said clamp element and said body restraining relative lateral movement therebetween.

5. A shankless tool bit and holder therefore combining a body member having a bit receiving recess at its forward end, said recess being defined by a lower flat bit seating surface and a rear abutment surface, said abutment surface being coextensive in width with said seating surface; a shankless L-shaped tool bit having lower and rear surfaces complemental to the surfaces defining the recess adapted to be fitted in said recess and to be adjusted laterally therein to various positions, said bit having at its rear an upper clamp engaging surface extending crosswise the tool bit; said body member also having a portion overlying said bit and bit recess with its under surface disposed at a relatively wide angle to the clamp surface of the inserted bit and spaced therefrom; a clamping wedge insertable in said space and having a portion thereof engageable with said upper surface of the bit and an opposite portion engageable with the under surface of said overlying portion of the body member, whereby said wedge is caused to transmit directly to the body member the forces tending to overturn said bit incident to the tooling operation; and means for urging said clamping wedge downwardly and rearwardly toeifect a clamping of the bit upon said seating surface and simultaneously against said rear abutment wall in any laterally adjusted position.

ERNEST REANEY.

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