US2889422A - Switch for a press - Google Patents

Description

June 2, 1959 D, DIBNER 2,889,422

SWITCH FOR A PRESS Filed May 27, 1955 INVENTOR.

DAVID Duma@ Mz Unite States Patent O SWITCH FOR A PRESS David Dibner, Wilton, Conn., assignor to Burndy Corporation, a corporation of New York Application May 27, 1955, Serial No. 511,659 6 Claims. (Cl. Zim-61.59)

My invention relates to a device for closing the electric circuit which controls the movement of the dies in a press.

A simple, inexpensive and instantaneously operated automatic tripping device is required, for example, to operate a high speed, strip terminal installation machine. Todays requirements for low cost, high volume solderless terminals require automatic installation machines which accept solderless terminals in strip form and which crimp these terminals around pre-stripped wires when the wires are inserted in the crimping portion of the machine -by the operator. Because these terminals are consumed in huge quantities, and because speed of installation is a prime factor in the acceptance of such terminals and installation tooling by high production manufacturers, it is of utmost importance that the installation machines perform the operation of assembling the terminal to the wire in a minimum amount of time. The most common type of terminal employed in high production, low cost applications are the so-called open 'barrel terminals, Where the barrel of the terminal consists of a U-shaped piece which is curled and closed around the conductor by the installation die. As a method of increasing the speed of operation of installation machines used with open barrel terminals, the stripped wire is inserted inside the die and against a stop plate, after which the press is engaged and the movable section of the die carries the wire down into the barrel and closes the barrel around it. The fact that the operator doesnt have to insert the wire in the barrel initially, but can simply place the wire within a considerably larger area and have the die carry the wire into its proper location, means a considerable increase in the speed of operation of such installation machines.

One method of operating the dies employs a foot switch which requires the openator to step on the switch to trip the press as soon as he has inserted the wire into the terminal. In speeding production with this method, even skilled operators frequently close the switch before a wire is fully inserted into the terminal, thereby making a faulty connection diliicult to detect.

A second method employs a pressure plate at the rear of the terminal which is attached to a micro switch. When the operator inserts the wire into the terminal and presses the plate, the switch is closed, tripping the press. This method avoids the limitations of the foot switch but has one of its own, namely that in View of small diameters, insufficient strength exists to permit the firm pressure against the plate required to operate the switch.

rl`he third method requires an electric circuit between the terminal, the inserted wire, and a contact plate placed at the rear of the terminal. When the wire is inserted into the terminal, it closes the circuit between the terminal and the contact plate. Closing the circuit activates a relay which in turn closes the switch controlling the movement of the dies. This method is unsuited for some types of terminals.

The principal object of my invention is to provide a simple, inexpensive and instantaneously operated automatic tripping device for operating a high speed press, especially in the forming of terminal connections.

2,889,422 Patented June 2, 1959 lCC Other objects are to provide a tripping device which is sutiiciently large to permit contact anywhere on the device rather than in a speciiic position, that is foolproof, that does not require irm pressure, 'and that will not operate before the wire is fully inserted.

I accomplish these and other objects and obtain my new results as will be apparent from the device described in the following specification, particularly pointed out in the claims, and illustrated in the accompanying drawing in which:

Fig. l shows diagrammatically a side elevation of a typical die installation incorporating my invention with the die parts opened to receive a conductor for indentation to a connector.

Fig. 2 is a front view thereof with the conductor shown in section.

Fig. 3 is a fragmentary side elevation of a form of contact plate.

Figs. 4, 5, 6 and 7 are front views of various types of contact plates forming my invention.

Fig. 1 shows a typical press 10 provided with crimping dies used to install open barrel strip terminals. The die consists of the top half l2 which performs the crimping and the bottom half 14 which supports the strip terminals 16 during crimping. An electrified contact pad 18 constructed in accordance with my invention is located just behind the crimping portion 20 and in front of the shear blade 22. The specific terminal being crimped is located over the anvil 24. Slot 26 receives the shear knife when the dies 4are closed.

Normally used and not shown is a clutch which activates the press operated by an electric solenoid whose circuit is closed by the electrified contact pad. Wires 28 carry the potential from the connections 29 and 31 of the electrilied contact pad 18 to the solenoid. Screws 30 hold the electrified contact pad against the support bracket 32.

In the normal, open position of the die, the wire 34 is inserted inside the die through the large opening 36 provided above the terminal and underneath the terminal crimping portion Ztl. The operator places the Wire against the electrified Contact pad 18. This pad, as shown in Figs. 2 and 3, consists of alternate spaced apart conductors 38 and 40. The conductors 38 and 40 are positioned almost liush with the surface of the pad 18, the representation in Fig. 3 lbeing exaggerated. A smooth surface on the contact pad is desirable so as to provide the least resistance against the end of the conductor when it is carried by the crimping die down into the terminal.

As soon as the Wire 34 touches electrified contact pad 18, it closes the circuit between any two or more of the electried strips, thereby closing the circuit and tripping the press. Therefore .the operator need only to touch the wire to any portion of the contact pad in order to activate the press.

The position of the installation dies during the closed, or crimping, portion of the cycle is shown in Fig. 2. Her-e the crimping portion 2l) has moved down with the ram 42 against the base 44 and anvil 24 carrying the wire 34 with it and forcing it into the open barrel terminal 16. The crimping die portion 2li has folded the U-shaped lbarrel 46 around the conductor 34 forming the iinal, crimped connection 48. Simultaneous with the crimping stroke of the die the shear blade 22 has severed the first terminal and has entered the groove in the base which received it and the portion of the terminal strip which has been sheared free. The circuit between wires 3S and 40 becomes open again. When the die returns to its original position, as shown in Fig. l, the terminal which has been crimped around the wire is now free from the original strip and is removed with the wire from the die. The strip is then automatically advanced by a mechanism, not shown, so that the next terminal is in position over the anvil Z4 and is ready for another wire.

In another variation of this type of strip-terminal crimping die, the terminals may be positioned side-by-side instead of extending end-to-end in line as shown in Fig. 1. The same electrified contact pad can be applied with equal effectiveness with this type of arrangement.

Various methods for fabricating the contact pad are possible. A printed circuit contact pad 18a is shown in Fig. 4. The two circuits which comprise the electrified part of the contact pad are made up by printing patterns 38a and 40a which are interspaced strips of electro-deposited metal. Each two adjacent strips therefore have an electrical potential between them. Lead wires are attached to the contact pad at connections 29a and 31a. The screw holes 50a are for the attachment screws 30.

A sandwich or laminate Contact pad 1817 is shown in Eig. 5. Here the alternate contact strips are made by cementing or bonding alternate strips of metal 38b and 40b with plastic spacers 52 in between so that every succeeding metal strip protrudes from opposite sides of the laminate where the strips of the same electrical circuit are joined together and attached to the respective lead wire terminals 29h and 3111. The metal strips may be made of copper or brass and the spacer strips can be made of any suitable dielectric material.

The wire wound contact pad 18e shown in Fig. 6, is provided with sets of small parallel grooves S4 and 56 machined or molded on the front side and between the two lateral edges of the pad. Two separate wires 38C and 40e are then wound around 4the pad in alternate grooves in such a. manner that the two wires provide the alternate potential contacts required. One end of each wire is attached to the lead wire contacts 29e and 31, respectively, and the other ends are terminated separately at the right side of the contact pad.

In the folded laminant contact pad 18d of Fig. 7, potential strips are formed by folding and refolding a thin plastic strip 58 which has been coated with a metal film 38d and 40d on its two sides. The folded strip is then cemented together so as not to unfold. Thus by making contact to both of the two separated metallic surfaces of the strip, the two alternate potential strips can be attached to the lead wire contacts 29d and 31d.

The electrified Contact pad forming my invention permits instantaneous electrical tripping of the press when the wire being installed in a terminal is placed anywhere on the large Contact pad surface, thus permitting an Operator far greater speed than if the wire had to be placed in one specific position before crimping.

In addition, the electrified contact pad permits instantaneous operation of the press involving the use of open barrel terminals and stop plates. The electrified contact pad permits fool-proof, instantaneous, automatic installation dies even when wires as line as AWG # 22 and 24 are used, where previously such fine wires would not perform satisfactorily with other methods of automatic tripping.

The electrified contact pad has no moving parts which can wear, go out of adjustment, or require maintenance.

With the electrified contact pad of my invention, perfect connections are assured in that the installed wires must be inserted to the proper distance before the press can be tripped.

I have thus described my invention, but I desire it understood that it is not confined to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of my invention, and, therefore, I claim broadly the right to employ all equivalent instrumentalities coming within the scope of the appended claims, and by means of which objects of my invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to attain these objects and accomplish these results.

I claim:

l. A press having upper and lower die parts for pressing a metal part thereto and operating means to cause the die parts to press the metal part, an electrical circuit connected to said operating means, a switch in said circuit positioned adjacent the die parts and supported thereto, comprising an insulating base member and a pair of electrical conductors having exposed surfaces projecting above the insulation of the base member, said conductors being positioned sufficiently apart to prevent contact with each other, whereby a metal part extending through the die parts may directly engage adjacent conductors and cause a flow of current in the circuit to operate the press.

2. The press of claim 1, wherein the pair of conductors in the switch extend over an area substantially larger than the end of the metal part to enable the metal part to close the circuit by striking any portion of the area.

3. A switch for closing a circuit comprising a supporting rigid base, a pair of electrical connections and a pair of printed electrical conductors mounted on said base and leading to said connections, said conductors having exposed surfaces and being positioned just suliiciently apart to prevent contact with each other and projected above the level of the base to permit direct contact therewith, whereby the circuit is closed by any metallic object touching the electrical conductors.

4. A switch for closing a circuit comprising a supporting rigid base, a pair of electrical connections and a pair of electrical conductors wound about said base and leading to said connections, said conductors having exposed surfaces and being positioned just suthciently apart to prevent Contact with each other and projected above the level of the base to permit direct contact therewith, whereby the circuit is closed by any metallic object touching the electrical conductors,

5. A switch for closing a circuit comprising a supporting rigid base, a pair of electrical connections and a pair of electrical conductors mounted on said base and leading to said connections, said conductors having exposed surfaces and being positioned just sutiiciently apart, by a plurality of layers of insulating material, to prevent contact with each other and projected above the level of the base to permit direct Contact therewith, whereby the circuit is closed by any metallic object touching the electrical conductors.

6. A switch for closing a circuit comprising a supporting rigid base, a pair of electrical connections and a pair of electrical conductors mounted on a sheet of flexible insulation material folded to produce a laminate structure with the electrical conductors extending therefrom and leading to said connections, said conductors substantially transversing said base a plurality of times and having exposed surfaces and being positioned just sufliciently apart to prevent contact with each other, projected above the level of the base to permit direct contact therewith, whereby the circuit is closed by any metallic object touching the electrical conductors.

References Cited in the file of this patent UNITED STATES PATENTS 1,285,986 Gralford Nov. 26, 1918 1,582,217 Henry Apr. 27, 1926 1,950,518 Read Mar. 13, 1934 2,127,538 Seiger Aug. 23, 1938 2,420,177 Krall May 6, 1947 2,556,390 Harrison .Tune 12, 1951 2,587,775 Sheldon et al Mar. 4, 1952 2,735,907 Inman Feb. 21, 1956 2,831,959 Jefferson Apr, 22, 1958

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