US3469481A

US3469481A - Hydraulic punching machine

Info

Publication number: US3469481A
Application number: US600992A
Authority: US
Inventors: Francis J Cloup
Original assignee: FRANCIS J CLOUP
Current assignee: FRANCIS J CLOUP
Priority date: 1965-12-11
Filing date: 1966-12-12
Publication date: 1969-09-30
Anticipated expiration: 1986-09-30
Also published as: FR1477469A

Description

mvenrbn:

Franci 5 J. CLOUP ATTORN BY F. J- CLOUP HYDRAULIC PUNCHING MACHINE 2 Sheets-Sheet 1 7 J 1 Q N w 2 W Sept. 30, 1969 Filed Dec. 12, 1966 Sept. 30, 1969 F. J. CLOUP 3,469,481

HYDRAULIC PUNCHING MACHINE Filed Dem-12. 1966 2 Sheets-Sheet B HgZ INVENTOR Francis J. CLOUP ATTORNEY United States Patent Int. Cl. iszsr 1/14 US. Cl. 83140 2 Claims ABSTRACT OF THE DISCLOSURE A hydraulic punching machine for punching metal sheets in which knocks and shocks produced by punching are automatically eliminated. This is achieved in a hydraulic punching machine in which the upper face of the hydraulic piston is subjected to a high hydraulic pressure by supplying means which apply a permanent damping fluid pressure to the lower face of the piston, said damping pressure being lower than the high pressure which is applied to the upper face of the piston. The means for applying this permanent pressure includes a modification of the fluid chamber of the machine. The damping pressure fluid penetrates into said chamber which contains the lower part of the piston through an opening having a cross section small enough to cause the necessary pressure loss between the upper face and the lower face of the piston.

The present invention relates to a high-power hydraulic punching machine that does not give any knocks or shocks upon clearance.

It is known that hydraulic punching machines produce knocks and shocks when the punch goes through the part to be punched. These knocks and shocks are due to the rapid cancellation of the elastic energy in the control hydraulic fluid located in the punching machine piston chamber.

According to the invention, these knocks and shocks are eliminated by applying, on a permanent basis a damping hydraulic fluid under intermediate pressure on the lower surface of the piston, this hydraulic fluid penetrating, in addition, into said chamber through a small section opening in such a manner that this intermediate pressure and the overpressure, due to pressure loss through this opening, balances the stress and energy available on the piston after punching or shearing of the iron sheet.

The invention will now be described in detail in relation to the attached drawings in which:

FIGS. 1 and 2 respectively show the punching machine of the invention and the punching machine separating unit; and

FIG. 3 shows this punching machine control hydraulic circuit.

Referring to FIG. 1, 25 designates, as a whole, a high power, for example 30 ton, punching machine, capable of punching holes 26 mm. in diameter into /2-inch mild steel.

The punching machine comprises a hollow body 1 fixed to a base 2 and a mobile piston 3 in the chamber of this body. 4 denotes the upper chamber above the piston and 5 the lower chamber below the piston. The driving hydraulic fluid is brought into the axis of the upper chamber 4 through pipe 6 under a pressure of the order of 3,500 p.s.i. and the damping hydraulic fluid is brought laterally into the lower chamber through pipe 7 and junction 8 under a pressure of the order of 700 p.s.i. Communication between lower chamber 5 and inlet channel 9 of the damping fluid occurs through a restricted passage 10. The size of this throttle passage is set so that the pressure loss due to the restriction together with the 3,469,481. Patented Sept. 30, 1969 intermediate pressure is sufficient to balance the high pressure of the driving fluid at the time where punching goes throughout.

The punch-bearing spindle 11 which is in the form of a hollow rod is screwed into piston 3. By screwing the punch-bearing spindle more or less into the piston, it is possible to set the punch in the vertical direction. Punch bearing spindle 11 is held in rotation by a spring catch 12 which goes into a groove in the punch-bearing spindle.

Piston 3 is held in rotation by a linchpin 13, keyed into the piston, which penetrates into an appropriate housing 14 of the punching machine body. During its penetration into this housing, linchpin 13 actuates two

push rods

15 and 16 of a micro-contact that controls the driving hydraulic fluid distributor.

Punch 17 is fixed to punch-bearing spindle 11 through sleeve 18. This sleeve is surrounded by separating unit 19 which consists of a perforated frame that has a lower part bearing on the part to be punched and an upper part surrounding the punch-bearing spindle and the sleeve which holds the punch to the punch-bearing spindle. A part 20 bearing a linchpin 21 can slide into a hole 22 inside the punch bearing spindle and this linchpin bears against the upper edge 23 of separating unit 19. Part 20 is pushed with respect to the piston by a spring 24.

Operation is as follows:

When the piston moves downwards, pressed by the under pressure liquid that feeds chamber 4, linchpin 21 is pressed on the edge 23 of the separating unit. At the end of a certain stroke, the lower part of separating unit 19 presses on the part to be punched, spring 24 begins to compress and the punch continuing its downward motion punches the part. The pressure and the energy absorbed in chamber 5 compensate for the elastic energy of the driving hydraulic fluid at the time of throughout punching. At the end of the stroke, the application of the driving fluid ceases and the piston is reset under the influence of the damping hydraulic fluid pressure and of spring 24 which tends to bring back the punch upwards by pressing on the separating unit, which thus maintains the plate into place during extraction of the punch.

FIG. 3 shows the punching machine control circuit. The oil under intermediate pressure to be used in damping and in resetting the punching machine, comes from an oleo-pneumatic accumulator 26 under a pressure of 700 p.s.i. and reaches the punching machine through pipe 7, junction 8, hole 9, and restricted passage 10. The oil to be used for control comes from a pump 27 and passes through a three-way and two-position distributor 28, controlled by the microcontact whose push-

rods

15 and 16 were mentioned in the description of FIG. 1, and by pipe 6. It can be seen that as the pressure in the lower chamber of the piston is maintained on a permanent basis, a four-way and three-position distributor of the type usually used with hydraulic jacks is not necessary.

In the punching machine example that has just been described, it has been supposed that the damping hydraulic pressure was 700 p.s.i. for a driving hydraulic fluid pressure of 3,500 p.s.i., that is, taking account the ratio of the cross-sections of chambers 4 and 5, a stress ratio on either side of the piston of 0.10. In fact, a ratio ranging between 0.05 and 0.30 may be adequate.

What I claim is:

1. A hydraulic punching machine for punching metal sheets in which knocks and shocks produced by punching are automatically eliminated comprising a body, a chamber in said body, a piston adapted to reciprocate in said chamber, a punch, means for securing said punch to said piston, a first source of high pressure hydraulic fluid feeding said chamber and actuating said piston by its upper face, a second source of damping hydraulic fluid which permanently feeds said fluid into said chamber at a pressure lower than said high pressure and which actuates said piston at its lower face, said chamber having a small opening through which said lower pressure damping fluid enters, and the section of said opening being dimensioned to provide a pressure loss at said upper face and said lower face of said piston respectively which is equal to the difference between said high damping pressure and said lower damping pressure.

2. A hydraulic punching machine for punching metal sheets in which knocks and shocks produced by punching are automatically eliminated comprising a body, a chamber in said body, a piston adapted to reciprocate in said chamber, a punch, means for securing said punch to said piston, a separating unit surrounding said punch and adapted to separate the punch from the sheet to be punched after punching, means for controlling said separating unit, a first source of high pressure hydraulic fluid feeding said chamber and actuating said piston at its upper face, a second source of damping hydraulic fluid which permanently feeds said fluid into said chamber at a pressure lower than said high pressure and which actu- References Cited UNITED STATES PATENTS 2,857,157 10/1958 Bonquet 83-615 X 2,039,847 5/1936 Howland-Shearman 83140X 2,612,951 10/1952 Palmleaf 83-639 X FOREIGN PATENTS 869,526 5/ 1961 Great Britain.

ANDREW R. JUHASZ, Primary Examiner US. Cl. X.R. 83-615, 639, 640