US3660883A

US3660883A - Portable press

Info

Publication number: US3660883A
Application number: US16462A
Authority: US
Inventors: Max Hoeckele
Original assignee: Karl Pfisterer Elektrorechnische Spezialartikel GmbH and Co KG
Current assignee: Karl Pfisterer Elektrorechnische Spezialartikel GmbH and Co KG
Priority date: 1970-03-04
Filing date: 1970-03-04
Publication date: 1972-05-09
Anticipated expiration: 1989-05-09

Abstract

An inexpensive portable pneumatic press which is intended primarily for compressing mechanical or electric connecting elements of electric conductors, cables and the like, in which a ram is driven by one or two cylinder-and-piston units extending transverse to the ram by means of at least one pair of toggle arms which are moved with an equal force toward each other. When the ram approaches its final compressing position, the toggle arm acts upon a control member which shifts the control valve to its venting position.

Description

ill

mted States Patent [151 Hoeckele May 9, 1972 PORTABLE PRES 3,398,567 8/1968 Olsson ..29/203 DT 72 l nt Max Hoeckel St h, G 1 emac many FOREIGN PATENTS OR APPLICATIONS {73 1 Ass'gnee Karl. l Fabnk elektmtechmscl" 289,506 7 1953 Switzerland ..29/200 Spezmlarttkel, Stuttgart-UnterturkheIm, 427 944 7/1967 Switzerland 79/200 Germany [22] Filed: Primar i- E.\'aminer-Thomas H. Eager [211 App. No: 16,462 Atlorney-Arthur O. Klein 57 ABSTRA T [30] Foreign Application Priority Data 1 C An inexpensive portable pneumatic press which is intended Feb. 18, 1970 Germany ..P l9 12 908.9 primarily for Compressing mechanical or electric connecting elements of electric conductors, cables and the like, in which a U.S. ram i driven one or two cylinder.and piston units extend. [5 lnt. transverse to the'ram means of at least one pair of tog. Field of Search 13,203 203 gle arms which are moved with an equal force toward each 29/200 B other. When the ram approaches its final compressing position, the toggle arm acts upon a control member which shifts [56] References Cited the control valve to its venting position.

UNITED STATES PATENTS 13 Claims, 3 Drawing Figures 3,329,002 7/1967 Schwalm ..29/203 DT i 5 4/ E0 2/ 9 6 /9 /7'/6 40 I7 PATENTEDMAY 91972. 3,660,883

SHEET 1 OF 3 In ventor:

Max HOE 5M by: I tOII'IBV PATENTEDHAY 91972 V 3,660,883

SHEET 2 0F 3 Inventor Max HOEfKEL E by: M

Attornev FA'TE'NTEMY 91972 V 3,660,883

arm 3 0F 3 Inventor:

Max HOECKELE by: M4 AH ornev PORTABLE PRESS The present invention relates to a portable press, especially for compressing mechanical or electrical connecting elements of electric conductors, which comprises a ram which is movable toward a fixed abutment by means of a pair of arms which are pivotably connected at one end to the ram and at the other end to a cylinder-and-piston unit which is operated by compressed air so as to drive the ram.

In portable presses which should be capable of compressing connecting elements of conductors of small as well of large cross-sectional sizes it has always been a problem to provide suitable means for producing the different high pressures which are required for properly compressing the different connecting elements. In manually operated presses in which the force which the operator exerts upon a hand lever is transmitted to the ram by means of a bell crank, toggle lever or an eccentric, the compressive forces which may thus be produced are relatively small unless an additional transmission or a very long hand lever is provided. Such an additional transmission or such a long hand lever renders, however, the manipulation of such a press unnecessarily difficult if only small compressive forces are to be exerted. While such presses whichare driven hydraulically easily permit very high pressures to be produced, the pumping movement which has to be carried out by means of a hand'lever or the like requires, however, an excessive length of time if only small pressures have to be exerted upon small connecting elements since the ram of the press has to be moved in all cases along the entire distance which is necessary to close the tool. In order to overcome this and other disadvantages of a hydraulic drive of such a press, it has been proposed to employ a cylinder-and-piston unit in which the piston is driven by conducting gases into the pres sure chamber of the cylinder which are produced by the explosion of a cartridge. However, these explosion drives also have a series of disadvantages, chiefly among them the fact that the deformation of the connecting element occurs too suddenly and that the ratio between the power and distance of travel of the piston is very unfavorable inasmuch as the force of the piston which is produced by the expansion of the explosion gases diminishes the farther the piston has to travel. It is therefore necessary to employ cartridges with different propellant charges in accordance with the different cross-sectional sizes of the connecting elements which are to be compressed. This involves the danger that a cartridge of an improper strength might be employed and that the connecting element may either be mashed or insufficiently compressed. Finally, there have also been presses of this type which were operated by compressed air by means of cylinder-and-piston units. These known pneumatic presses were, however, of an expensive construction and also very uneconomical because they required very large amounts of compressed air.

It is an object of the present invention to provide a portable press of the type as described at the beginning which is operated pneumatically, is of a simple and inexpensive construction, may be easily manipulated to compress connecting elements and the like of different cross-sectional sizes, and is capable of producing high pressures and of being operated very economically. According to the invention, this object is attained by moving the ram of the press by means of at least one pair of arms which are pivotably connected at one end to the ram and at the other end to two connecting elements which are movable in opposite directions to each other and transverse to the direction of movement of the ram. At least one of these'connecting elements is formed by a piston rod of a pneumatically operated cylinder-and-piston unit. Further features of the invention for attaining the above-mentioned object consist in the provision of a throttle member in the compressed-air line leading to the cylinder of this unit, in

providing a control valve which by the manual actuation of a trigger is movable from a position in which it vents the compressed-air line leading from this valve to the cylinder to the operating position in which it connects the supply line of the compressed air to the cylinder so that the piston in this cylinder will be driven and the ram will carry out a compressing stroke, and in further providing the movable member of this control valve with a control member which, when the trigger is actuated, projects into the path of travel of the mentioned connecting elements so that, when the piston arrives at a point near the end of its driving stroke, these connecting elements will engage upon this control member and thereby shift the valve member to its venting position so that the ram and piston may then be retracted by at least one return spring.

Due to the provision of the togglelike connecting arms intermediate the piston rod and the ram, the ration between the distance of travel and the force exerted by the ram is very favorable since at first the ram carries out very quickly a relatively long part of its stroke and near the end of its entire stroke exerts an increased pressure. It is therefore possible by means of a relatively small cylinder-and-piston unit and a pressure as supplied by a conventional source of compressed air to produce the required ram pressure for compressing connecting or other elements of large cross-sectional sizes. A very important feature of the invention also consists in the provision of the throttle member which retards the build-up of pressure in the pressure chamber of the cylinder of the pneumatic unit. This prevents the compressionv of the connecting or other elements from being carried out too quickly and it also reduces the required amount of compressed air to a minimum since the movement of the piston is carried out in accordance with the pressure which the ram has to exert, and therefore only such a pressure has to be produced in the cylinder as is actually required. A further increase in pressure in the cylinder and thus an unnecessary consumption of compressed air is avoided according to the invention by the provision of the control member which automatically interrupts the supply of compressed air when the ram reaches its final compressive position. In order to carry out a compressing operation, the operator therefore needs to do no more than to actuate the trigger. This fact and the low weight of the entire press which is due to its simple construction permit the press to be very easily manipulated.

According to one preferred embodiment of the invention, the press needs to be provided only with a single cylinder-andpiston unit. While in this embodiment, one of the two connecting elements is, of course, pivotably connected to the piston rod, the other connecting element is pivotably connected to the cylinder. This is insofar of advantage as the forces which are exerted by the connecting elements upon the two arms will necessarily be of exactly the same strength and no force of reaction will occur which may have to be taken up by a housing or other supporting elements of the press. Since in this case not only the piston but also the cylinder carries out a movement, provision has to be made to permit the air supply line leading to the cylinder not to interfere with this movement of the cylinder. Although this supply line could, of course, consist of a flexible tube, it has been found to be of advantage to make it of two sections which are telescopically slidable within each other but are tightly sealed relative to each other and extend parallel to the longitudinal axis of the cylinderand-piston unit.

According to another preferred embodiment of the invention, the press is provided with two cylinder-and-piston units which are preferably coaxial and the pistons of which are movable in opposite directions to each other, while their cylinders are rigidly connected to each other. The two connecting elements may in this case consist of the two piston rods.

Regardless of whether the press is equipped with a single cylinder-and-piston unit or with two of such units, it is of advantage to connect one end of at least one further arm pivotally to each connecting element in a position coaxially to the pivot axis of the arm which connects this element to the ram and to connect the other end of this further arm pivotably to a tool supporting head in which the ram is slidable and which also carries the fixed tool and takes up directly the force of reaction of the ram.

The throttle member may be of a very simple type which consists of a threaded pin which is loosely inserted with play into a tapped bore. It has been found to operate very reliably.

The control valve may consist of a slide valve which is provided with connecting bores and is axially slidable in a connecting block, while the control member for returning this slide valve to a position in which it shuts ofi the compressed air supply line and vents the cylinder may simply consist of one or a pair of projections which, when the valve member is moved by the trigger to its operative position, projects into the path of travel of the connecting elements or the anns thereon and is engaged by the latter at the ends of their movement toward each other when the ram reaches its full compressive position and is then depressed by a cam action so as to move the valve member to its venting position.

The features and advantages of the present invention will become more clearly apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIG. 1 shows a longitudinal section of the portable press according to a first embodiment of the invention;

FlG. 2 shows a cross section which is taken along the line ll ll of FIG 1; while FIG. 3 shows a longitudinal section of the press according to a second embodiment of the invention.

As illustrated particularly in FIG. 1 of the drawings, the portable press according to the invention which is to be employed, for example, for compressing clamps, connecting terminals, connecting sleeves and the like comprises a substantially C-shaped head 1 which has two arms which are provided with coaxial bores 2 and 3 which extend parallel to the yoke of this head 1. Bore 2 is adapted to receive the mounting pin ofa fixed tool 4 of an associated pair of tools, while the other tool 4' rests on one end surface of a ram 5 and is held in this position by its mounting pin which is inserted into an axial bore of the ram 5. Ram 5 is axially slidable within and guided by the wall of bore 3 and surrounded by a coil spring 6 which engages with an initial pressure at one end upon the head 1 and at the other end upon the enlarged base 5' of ram 5. Due to this enlarged base 5, ram 5 is substantially T-shaped.

This base 5' of ram 5 is provided with two parallel bores which extend symmetrically to the longitudinal axis of ram 5 and at right angles to the direction of movement of the ram and contain two hinge pins 7 which are locked in a fixed position by screws 8. Two pairs of equal arms 9 are pivotably mounted at one end on each of these pins 7, while the other ends of one pair of these arms 9 are pivotably connected by a pin 10 extending parallel to the pins 7 to one end ofa connecting rod 11 which extends transverse to the longitudinal axis of ram 5. The other end of this connecting rod 11 forms a flange 11' of a larger diameter, and this flange and the connecting rod 11 are provided with a central socket bore 12 the bottom of which is located near the pin 10. The wall of this bore 12 is provided with two diametrically opposite longitudinal slots 13 at the sides facing the arms. 9.

The other end of the second pair of arms 9 is pivotably connected by a pin 14 to a piston rod 15 the enlarged head of which is guided by the wall of the central bore 12, while pin 14 projects through the longitudinal slots 13 of rod 11. Flange 11 is screwed into the open end of a cylinder 17 of a cylinderand-piston unit 16. Piston rod 15 is connected to a piston 18 which is slidable within the cylinder 17 and carries a coil spring 40 which surrounds the piston rod 15 and is pressed against flange 11' when during its driving stroke piston 18 has traveled for a certain distance from the bottom 17 of the cylinder,

Two equal pairs of arms 19 are further pivotably connected at one end to

pins

10 and 14, respectively, and at the other end to a pair of

pins

20 and 21 which extend parallel to

pins

10 and 14 through the arm of head 1 in which the bore 3 is provided and are equally spaced from this bore 3. Spring rings 41 or the like on the ends of

pins

10, 14, 20 and 21 prevent these pins from sliding out of the bores into which they are inserted.

At the side of the connecting rod 11 opposite to ram 5 a connecting block 23 is mounted in a fixed position in a housing 22. This connecting block is provided in axial alignment with ram 5 with a bore in which a slide-valve member 24 is slidable which has a U-shaped control member 25 secured to its end facing the ram 5. As may be seen in FIG. 2 the two parallel arms of this control member 25 are spaced from each other at a distance which is substantially equal to the distance between the two arms 9 and, as shown in FIG. 1, the free ends of these arms of the member 25 are rounded. The other end of valve member 24 which likewise projects from the connecting block 23 engages upon one end of a trigger 26, which is pivotably mounted in the housing 22, and the other end of which projects from this housing so as to be easily manipulated. When this end of trigger 26 is depressed, valve member 24 will be shifted against the action of a return spring in the direction toward the ram 5.

At the side of the connecting block 23 facing the cylinderand-piston unit 16 this block 23 carries a guide tube 28 which extends parallel to the longitudinal axis of cylinder 17 and the bore 27 of which is connected with the bore in which the valve member 24 is slidable and also contains one end of a connecting tube 29 which is axially slidable in this bore 27, while the other end of tube 29 is inserted into the bottom 17' of cylinder 17 and communicates through a connecting bore in the bottom 17 with the cylinder chamber. An annular gasket 30 prevents the compressed air from passing between the outer wall of tube 29 and the inner wall of guide tube 28 to the outside. The slight movement of the cylinder-and-piston unit 16 transverse to its longitudinal axis which may occur during the pressing operation of the apparatus leads to a slight bending of the connecting tube 29 which is, however, so elastic that the tight sealing action of gasket 30 will not be impaired.

The wall of the bore in block 23 in which valve member 24 is slidable is provided at a certain distance in the axial direction of this bore from the point where bore 27 terminates into it with a second bore 31 into the outer threaded end 32 of which a setscrew 33 is loosely inserted and forms a throttle member. This threaded bore 32 is connected between the rear end of the head of setscrew 33 and a screw 34 which closes the outer end of bore 32 to another bore which leads to a connecting line 35 which may be connected to a source of compressed air, not shown.

Valve member 24 has a central bore 36 which is closed at both ends, and two

transverse bores

37 and 38 which are spaced from each other at a distance equal to the distance between the two connecting bores 27 and 31.

When the apparatus is in its released position as shown in FIG. 1, bore 37 of valve member 24 is in axial alignment with the connecting bore 27, while bore 38 is located outside of the connecting block 31 so that the pressure chamber of cylinder 17 is vented via tube 29 and the mentioned bores. In the operative position of valve member 24, however, bore 38 is in alignment with the other connecting bore 31. When valve member 24 is in this position, the two arms of the control member 25 also project into the path of movement of the lower ends of the arms 9.

The mode of operation of this press is as follows:

When one pressing operation has been completed, all movable parts of the press are automatically shifted to the position as illustrated in FIG. 1. For effecting the next pressing operation, trigger 26 is depressed and valve member 24 is thereby shifted to its operative position in the direction toward the ram 5. Compressed air may then flow through the connecting line 35, the throttle 33, the valve bores 31, 36 and 37 and the bore 27 and then through the connecting tube 29 to the pressure chamber of cylinder 17 so that the piston 18 will be moved toward the flange 11' and pins 10 and 14 will thereby be moved with an equal force toward each other. Since due to the throttle 33 the pressure will be built up slowly in the pressure chamber of cylinder 17, this pressure will at any time only have the strength as required by the particular position of ram 5. As soon as ram 5 reaches its end position, the ends of arms 9 which are pivotably connected to pins and 14 also reach a position in which they push the control member 25 which is located between them by a cam action so far in the direction toward the connecting block 23 that a further supply of compressed air will be stopped and valve member 24 will be returned to the venting position as shown in FIG. 1. The compressed air can therefore escape from the pressure chamber of cylinder 17 and pass to the outside. Suitable means, not shown, may be provided to reduce the noise of the escaping compressed air. Ram 5, arms 9, piston 18 and arms 19 will then be returned to their original positions as shown in FIG. 1 at first by the action of both

springs

6 and 40 and then only by the action of spring 6. The connecting tube 29 is then also pushed back to its original position in guide tube 28 from which it was pulled out during the pressing operation for a distance in accordance with the shifting movement of the cylinder. Since spring 40 will be compressed only during a part of the stroke of piston 18, the amount of compressed air required for the pressing operation will be reduced.

The second embodiment of the invention as illustrated in FIG. 3 differs from the first embodiment as shown in FIGS. 1 and 2 merely by the provision of two cylinderand-piston units l16-and 116. These two units are of identical construction and extend coaxially to each other, and their

pistons

118 and 118 which are disposed at opposite sides of the housing 122 operate in opposite directions to each other. The connecting member 111 which again extends transverse to the direction of movement of ram 105 is provided on each end with a flange 111' which is screwed into the associated cylinder and thus connects both cylinders to each other. The pair of arms 109 which correspond to the arms 9 in FIGS. 1 and 2 which are connected to the base of the ram 105 are in this case connected to the piston rod 115, 115' of the cylinder-and-

piston unit

116, 116. A further difference between this embodiment of the invention and that according to FIGS. 1 and 2 consists in the provision of an additional connecting tube 123' which leads from the connecting block 123 to the pressure chamber of the cylinder of the cylinder-and-piston unit 116'. Furthermore, the connecting

tubes

129 and 129 are rigidly connected to the connecting block 123 and do not need to be telescopically slidable relative to this block since the two cylinders are not movable relative to the housing 122.

In order to prevent the trigger of the press as shown in FIG. 3 from being depressed accidentally when the press is not to be operated immediately, the part of this trigger which projects from the housing 122 is completely covered by a safety cap 140 which is connected to the housing so as to be pivotable about an axis 141, while a spring 142 tends to maintain this cap 140 in its closed position. In order to be able to actuate the trigger, the operator of the press must therefore first pivot the safety cap 140 in the clockwise direction, as seen in FIG. 3, which he may do with one finger of the same hand holding the housing 122 or with his other hand. Although this safety cap may be of any other suitable construction, it is shown in FIG. 3 as consisting of an inner part 140{ of sheet metal which is covered by an outer layer 140" of plastic.

Apart from the differences as previously described, the press as illustrated in FIG. 3 is of the same construction as the press as shown in FIGS. 1 and 2. Of course, the last-mentioned feature of providing a safety cap for the trigger may also be applied to the press according to FIGS. 1 and 2 to cover the trigger 26.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, 1 wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim is:

l. A portable pneumatic press for compressing electrical connecting elements of electrical conductors, cables, and the like, comprising a tool support having an abutment, a ram axially slidable in said tool support relative to said abutment, at

v least one cylinder-and-piston unit having a piston rod, a pair of connecting elements movable in opposite directions to each other and transverse to the direction of movement of said ram, at least one of said connecting elements being rigidly secured to said pistonrod, at least one pair of driving arms pivotably connected at one end to said connecting elements and at the other end to said rarn, an air supply line for conducting compressed air to the cylinder of said unit, a throttle member in said supply line, a control valve in said supply line, a control member connected to said valve and having one end adapted to project into the path of travel of said connecting elements and to be acted upon by the latter when said rarn reaches its full compressing position so as to move said valve member to its venting position, and a manually actuated trigger for shifting said valve member from said venting position to a position in which it connects said supply line to said cylinder.

2. A portable press as defined in claim 1, in which one of said connecting elements is secured to said piston rod and the second connecting element is secured to said cylinder.

3. A portable press as defined in claim 2, in which said second connecting element forms a rod having a central bore, said first connecting element being slidable within and guided by the wall of said bore, said wall having a pair of longitudinal slots diametrically opposite to each other, and pivot pins connecting said connecting elements to said driving arms, at least one of said pivot pins projecting through and slidable along said slots.

4. A portable press as defined in claim 1, in which said air supply line leading to said cylinder has a part extending parallel to the longitudinal axis of said unit, said part being divided into two sections which are telescopically slidable relative to each other, and means for sealing said two sections relative to each other.

5. A portable press as defined in claim 1, in which two of said cylinder-and-piston units are provided, the pistons of said two units being movable in opposite directions to each other and the two cylinders of said units being secured to each other, said two connecting elements being secured to the piston rods of the associated pistons.

6. A portable press as defined in claim 5, in which said two cylinders are secured to each other by a rod having a central bore, the piston rods of said two pistons being slidable within said bore and guided by the wall thereof, said wall having a pair of longitudinal slots diametrically opposite to each other and terminating into both cylinders, and pivot pins connecting said connecting elements to said driving arms and projecting through and slidable along said slots.

7. A portable press as defined in claim 3, further comprising at least one pair of second arms also pivotably connected at one end to said pivot pins and at the other endto said tool support.

8. A portable press as defined in claim 1, further comprising spring means for returning said ram and the piston of said unit after each driving stroke.

9. A portable press as defined in claim 1, in which said throttle member consists of a threaded pin loosely inserted with play into a tapped bore. v

10. A portable press as defined in claim 1, in which said control valve comprises a connecting block and a slide valve member slidable in said connecting block and having connecting bores.

11. A portable press as defined in claim 10, in which said valve member extends coaxially to said ram and is slidable in the longitudinal direction of the latter and located at the side facing the side of said ram to which said driving arms are connected, said control member being adapted to project from said valve member into the path of travel of said driving arms.

12. A portable press as defined in claim 11, in which the end of said valve member opposite to that carrying said control member engages upon said trigger, and spring means tending to maintain said valve member in a retracted position and in engagement with said trigger.

13. A portable press as defined in claim 1, further comprising a housing covering at least some of the elements of said press and having an aperture, said trigger pivotably mounted on said housing and partly projecting through said aperture to the outside, a cap adapted to cover the outwardly projecting part of said trigger, and a spring normally tending to maintain said cap in said covering position.

* It i

Claims

2. A portable press as defined in claim 1, in which one of said connecting elements is secured to said piston rod and the second connecting element is secured to said cylinder.
3. A portable press as defined in claim 2, in which said second connecting element forms a rod having a central bore, said first connecting element being slidable within and guided by the wall of said bore, said wAll having a pair of longitudinal slots diametrically opposite to each other, and pivot pins connecting said connecting elements to said driving arms, at least one of said pivot pins projecting through and slidable along said slots.
4. A portable press as defined in claim 1, in which said air supply line leading to said cylinder has a part extending parallel to the longitudinal axis of said unit, said part being divided into two sections which are telescopically slidable relative to each other, and means for sealing said two sections relative to each other.
5. A portable press as defined in claim 1, in which two of said cylinder-and-piston units are provided, the pistons of said two units being movable in opposite directions to each other and the two cylinders of said units being secured to each other, said two connecting elements being secured to the piston rods of the associated pistons.
6. A portable press as defined in claim 5, in which said two cylinders are secured to each other by a rod having a central bore, the piston rods of said two pistons being slidable within said bore and guided by the wall thereof, said wall having a pair of longitudinal slots diametrically opposite to each other and terminating into both cylinders, and pivot pins connecting said connecting elements to said driving arms and projecting through and slidable along said slots.
7. A portable press as defined in claim 3, further comprising at least one pair of second arms also pivotably connected at one end to said pivot pins and at the other end to said tool support.
8. A portable press as defined in claim 1, further comprising spring means for returning said ram and the piston of said unit after each driving stroke.
9. A portable press as defined in claim 1, in which said throttle member consists of a threaded pin loosely inserted with play into a tapped bore.
10. A portable press as defined in claim 1, in which said control valve comprises a connecting block and a slide valve member slidable in said connecting block and having connecting bores.
11. A portable press as defined in claim 10, in which said valve member extends coaxially to said ram and is slidable in the longitudinal direction of the latter and located at the side facing the side of said ram to which said driving arms are connected, said control member being adapted to project from said valve member into the path of travel of said driving arms.
12. A portable press as defined in claim 11, in which the end of said valve member opposite to that carrying said control member engages upon said trigger, and spring means tending to maintain said valve member in a retracted position and in engagement with said trigger.
13. A portable press as defined in claim 1, further comprising a housing covering at least some of the elements of said press and having an aperture, said trigger pivotably mounted on said housing and partly projecting through said aperture to the outside, a cap adapted to cover the outwardly projecting part of said trigger, and a spring normally tending to maintain said cap in said covering position.