US 1797987 A
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Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE FLOYD C. KING, 0F BIRMINGHAM, MICHIGAN, ASSIGNOR T0 GUARDIAN TRUST COM- PANY, OF DETROIT, MICHIGAN, A CORPORATION 0F MICHIGAN, TRUSTEE PUNCH Application led June 10, 1929. Serial No. 369,905.
This invention relates generally to punches and refers more particularly to the type of.
punch set forth in my applicationfiled February 11, 1929, bearing Serial No. 339,145.
One of the essential objects of the invention is to provide a punch that will be effectively held in, but may be easily and quickly released from a holder such as that set forth in the application above mentioned.
the invention consists of certain novel features of construction that will be hereinafter more fully described and particularly pointed out inthe appended claims.
In the accompanying drawing: Figure 1 is a vertical sectional View through a retainer and showing a punch embodying my invention in operative position in said retainer;
Figure 2 is a detail view of the punch; Figure 3 is a sectional vieWt-aken on the line 3-3 of Figure 2.
Referring now to the drawings, 1 is a punch having suitable shank and Work engaging head portions, 2 and 3 respectively, 4 is a retainer body having a bore 5 for receiving the shank 2 of the punch and having a pocket or recess 6 at one side ofthe bore containing means for retaining the'shank 2 in the bore 5. As shown the means in the recess 6 in the holder 4 for retaining the punch shank 2 in the bore 5 comprises a lever y 14' having a rounded or spherical end portion 15 pivotally engaging a rounded portion 16 of the recess 6 and preferably having an arcuate end portion 17 engageable With the longitudinally curved base 18 of an arcuate recess 19 in one side of the punch shank 2, a coil spring 20 engaging the lever 14 and normally holding the arcuate end portion 17 thereof in the bore 5, and a shell 21 that constitutes a housing for the spring 2O and for the spherical end portion 15 of the lever and that prevents accidental displacement of the said spherical portion 15 y from-the rounded portion 16 of the recess 6.
The rounded portion 16 of the recess 6 is concentric with the center 22 of the spherical portion 15 and constitutesv a hacker or bearing for said spherical portion in all positions of pivotal adjustment of the lever. In fact, the arrangement of the spherical end rounded portions 15 and 16 respectively is such that the spherical portion 15 slidably engages the rounded portion 16, and the outer free end of With the above andother objects in View;
the lever is so fashioned With respect to the base 18 of the recess 19 in the punch that the longitudinal thrust imparted to the lever when the free end thereof is engaged With the base 18 of said recess is transmitted directly from the spherical portion 15 to the rounded portion 16.. Therefore, as the lever swings in an arc the spherical portion! 15 Will transmit this thrust or load to correspondingly dierent points of the rounded portion 16. Moreover, due to this arrangement of the spherical androunded portions, the outer free end of the lever may be so fashioned that the punch will be effectively held by the lever acting as a prop or brace and may be easily and quickly released from the lever and removed from thev body 4 as Will be hereinafter more fully set forth. p
Preferably the arcuate endl portion 17 of the lever is eccentric to the center 22, said arcuate end portion 17 being concentric with an eccentric point 22 of the spherical portion 15. Moreover, When the parts are in the position illustrated in Figure 1, the longitudinally curved base 18 of the recess 19 in the shank 2 is also eccentric to the center 22, but concentric with the arcuate end portion 17, the dotted line in Figure 1 representing an arc concentric With the center 22. As shown the recess 19 is adjacent to the upper end of the shank 5, hence when the arcuate end portion 17 engages Vthe base 18 of the recess in the tool shank 2, a propping or bracing action in contradistinction to a Wedging action, and an area contact instead of a point contact is obtained. Likewise when the lever is'raised the end portion 17 is released from the base 18 and is therefore readily re- 17 of the lever will automatically engage the` base 18 of the recess 19 in the shank 2 and position. However, any suitable means such as the shank. 50 of a. tool 51 may be inserted through a bore 25 into the recess 6 to disengage the lever 14 from the shank .2.
readily removed from a holder without the necessity of taking apart the holder or separating it from the usual backing plate 40. Moreover, a better gripping action is obtained 20 and there is no tendency of the parts to wedge.
In the preferred embodimentof my invention, the recess 19 in the shank 2 is transverselv curved in arcuate form as indicated at 18A. The recess may be described as having a surface formed bv the intersection of a tore with the cylindrical shank 2. In the preferred construction the tore defining the curvature of the recess has anvoutside diameter' substantiallv three times the diameter of the generating circle which defines the transverse curvature. The depth of the recess is preferablv 1/3 of the diameter of the generating circle.
It is desirable that the recess 19 be main-I tained cuite accurately within certain limits of tolerance Aand one specific construction that has proved to have exceptional merit has a generating circle corresponding to the following formula:
In this Ycase the depth of the recess corresponds to the following formula:
MA=.333 MC- .0104i .010
In the above formulas MA represents the depth of the recess, MC the diameter of the generating circle and MB the outside diameter of the tore. 5 What I claim as my invention is:
1. A punch having a longitudinally extending groove, theJ surface of said groove corresponding to a" tore in which the gengroove having a depth approximately 1/3 of the diameter of the generating circle of said tore.
2. A punch having a longitudinally extending groove arcuately curved both longitudinally and transversely, the diameter of the transverse curvature being substantially U5 and the depth ofthe groove being substanwill effectively hold the punch in assembledL Thus, withmv construction a tool may be erating circle is substantially l the diame- 1,45 the diameter of the longitudinal curvature tially 1/3 the diameter of the transverse arcuate curve.
3. A punch having a longitudinally extending groove having a sur ace such as is formed by the intersection of a cylinder with a tore in which the tore has a generating circle substantially equal to 1%; of the outside diameter of the tore minus 315 of an inch, said groove having a depth-approximatel 1/3 -the iameter of the generating circle o sald tore.
In testimony whereof I aiiix my signature.
FLOYD C. KING.