Center punch

Aug. 22, 1950

2,519,908

A. HOWARD ET AL

CENTER PUNCH

Filed March 29, 1949

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INVENTORS

ARCHIE HOWARD

WALTERL. MORRISON =4 T //J'HNEY

Patented Aug. 22, 1950

2,519,908

F UNITED STATES PATENT OFFICE

2,519,908

CENTER PUNCH

Archie Howard and Walter L. Morrison, Richmond, Ind.

Application March 29,1949, Serial No. 84,035

Claims.

This invetitioii relates to cehtef punches for use in pattern plate transfers, and has for its object to provide a device of this type whereby the center· markings upon a work piece from a pattern having holes of different diameters can be rapidly and easily accomplished in a simple manner.

Another object of this invention is to provide a marking device in which the operation of entering it into the pattern hole ahd applying pressure will automatically adjust it to its Ce'ht'ering position with respect to the work material.

Other objects of the invention relate to the structural features resulting in a simple device of the fewest possible parts, economically produced, easily assembled and convenient to use.

Our invention is illustrated in the accompanying drawing, in which

Fig. 1 is a fragmentary side elevational view of the device in normal position.

Fig. 2 is an end view of Fig. 1.

Fig. 3 is a cross-sectional view taken upon line 3—3 of Fig. 1.

Fig. 4 is a fragmentary side elevational view of the device in operated position.

Fig. 5 is an end view of the parts as shown in Fig. 4.

Fig. 6 is a fragmentary view with parts in section showing a modification of the device of the invention in normal position in a hole of a pattern plate, and

Fig. 7 is a view of the parts shown in Fig. 6 with the device expanded.

As shown in the drawings, a tubular member of resilient metal is divided at one end into a plurality of resilient arms 6 by means of slits 7 extending for a distance longitudinally of the tube 5. In its portion beyond the ends of the slits, the tubular member 5 is provided with a knurled portion 8.

Located in the tubular member 5, and longitudinally movable therein, is a punch rod 10 of hardened steel. Upon its lower end, the punch rod IB is formed with an enlarged tapered collar member 11, and a prick punch extension 12.

At its upper end, the punch rod IB extends beyond the end of the tubular member 5, and is screw-threaded, as at 13, to receive a screwthreaded head i 4, which provides a tapping surface for a hammer. The head is provided with a knurled surface 15 for easy handling.

At their lower ends, each of the resilient arms is provided on its inner surface with a bevel or chamfer as indicated at 16 (Fig. 3). This bevel is of the same taper as the taper on the (Cl. 33—191) collar ί ί so that it Will fide easily OVef the collar when the tubular member and the punch rod are moved relative to each other, th the smaller sizes of punches, the outside di- ametef of the tubular member 5 may be substantially the same aS the greatest diameter of the collar 11 Oii the punch fed, as sMwn in Fig, 6. This relation of the parts insures that the lower ends Of the resilient members, may be entered in 10 a hole of sufficient diameter to receive the largest diameter of the tapered collar, thus adapting it to smaller holes.

In the modification shown in Figs. 6 and 7, a work plate 2B, which is to be marked, is shown 15 below a pattern plate 2 f, which is provided with a hole 22, to be centered upon the work plate 20. In Fig. 6, the device is shown in its normal position in the hole 22 of the pattern plate 21, in which position there will be a clearance between 20 the peripheral portions of the arms 6 and the inner diameter of the hole 22. By applying downward pressure to the tubular member 5, the ends of the resilient arms will be expanded over the tapered portion 11 of the punch rod 10 until the 25 outer surfaces of the resilient arms 6 will engage the inner surface of the pattern hole 22. In the position of the parts, a hammer tap on the head 14 will produce the desired drilling center.

In the modification illustrated in Figs. 6 and 7, ₃₀ the outside diameter of the tubular member 5, with the resilient member 6 in normal position, is the same as the largest diameter of the tapered collar 11 on the punch rod 10. This provides a structure which will accommodate itself ₃₅ to holes of less diameter than will the structure shown in Figs. 1 to 5.

The punch rod IB fits snugly in the upper end of the tubular member 5, but slides easily therein so that it is always accurately centered within ₄₀ the tube.

The device is characterized by its simplicity of operation, which adapts it to rapid and accurate transfer work.

It is apparent from the construction that the 45 simple acts of inserting the device into a hole until the lower end of the punch rod rests upon the work plate, followed by sliding the tubular member 5 downwardly upon the punch rod to expand the ends of the arms 6 to engage the periph50 ery of the hole of the pattern, will accurately determine the location for the punch mark.

This obviously is a one handed operation and may be performed as rapidly as the tool can be moved from one hole to the other and struck with the hammer.

2,518,908

A single punch may be made to handle holes of different diameters. For example, a tool which will center for a hole one-eighth of an inch in diameter, may center for all sizes of holes between one-eighth and three-sixteenths of an g inch. Larger punches will have a wider range. For example, a punch with a minimum of one inch may also serve to center a hole one and onehalf inches in diameter.

The punch rod may be easily replaced in case 10 the marker point becomes dulled or broken.

Although we have shown and described our invention with respect to certain details of construction, it is to be understood that we do not wish to be unduly limited thereto, certain varia- 15 tions from the disclosure being possible without departing from the spirit or scope of our invention.