Metal deforming – With means to handle work or product – Including product handling means
Patent
1988-09-28
1990-01-30
Larson, Lowell A.
Metal deforming
With means to handle work or product
Including product handling means
267119, B21D 4504
Patent
active
048965243
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an arrangement for the ejection of a pressed component from a press tool consisting of a number of ejection pins distributed over the press surface of the press tool, each of said pins being so arranged as to lie during the pressing operation with its tip no higher than on a level with the aforementioned press surface, and, in conjunction with the opening of the tool after a pressing operation has been completed, as to eject the component from the tool with its tip.
A critical factor which governs the efficiency with which a press can be used is the speed at which a pressed component can be removed from the press tool and new material can be introduced. The importance of the aforementioned operations being performed rapidly and with high precision is further accentuated in multi-stage presses of the kind which are found, for example, in the automobile industry, in which a fault in one of the pressing stages will prevent the execution of all the other stages.
A large number of solutions have already been proposed to the problem of rapidly achieving the ejection of the pressed component. In order to be able to guarantee that the surface finish of the components will not be damaged by the ejection pins at the plate thicknesses which are now common, it is necessary for the force exerted by each of these to be relatively small, that is to say a large number of ejection pins is required per unit of surface area. In the case of previously disclosed ejection devices, at least two hydraulic lines are required for each ejection pin, and since the design of press tools has now become extremely complex, it has proved necessary, partly for reasons of space, to accept a reduction in the number of ejection pins.
The object of the present invention is to make available an ejection arrangement of the kind referred to by way of introduction which will permit the use of a sufficiently large number of ejection pins per unit of surface area of the press surface of the tool for the surface finish of the pressed component not to suffer damage on being ejected, but without jeopardizing the function of the press tool by the presence of a large number of hydraulic lines for the ejection pins. This is permitted in accordance with the invention in that each ejection pin is operatively connected via a piston rod to a hydraulic piston which is capable of axial displacement in a hydraulic cylinder filled with an incompressible fluid in a space between the piston and an end wall of the cylinder, which space communicates via a duct with a drive unit for the ejection pins, which unit consists of a number of mechanically inter-connected hydraulic cylinders with associated pistons which corresponds to the number of ejection pins, the piston rods of which are so arranged as to be carried in a synchronous fashion by the moving half of the press tool, in conjunction with which the pistons are influenced by a spring device acting in the direction of ejection.
In accordance with a specific characteristic feature of the invention the cylinders are adjustable relative to a fixed reference for the purpose of achieving synchronism between the ejection pins.
A preferred embodiment of the invention is characterized in accordance with a second specific characteristic feature of the invention in that the hydraulic cylinder which interacts with the ejection pin is sealed against the corresponding piston rod, in that the space of the ejection cylinder filled with incompressible fluid is defined not only by the piston and the cylinder wall, but also by the end wall in which the seal against the piston rod is arranged, in that the duct is connected in an area close to the aforementioned seal, in that the pistons of the drive unit are of the plunger type, and in that the aforementioned spring is a gas spring which consists of a compressible fluid enclosed within a space which is defined by the piston of the ejection pin, the walls and the end wall of the hydraulic which interacts with the ejection pin at the opposite end to th
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patent: 1571673 (1926-02-01), Jayne
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patent: 3805577 (1974-04-01), Bergemann
patent: 3911718 (1975-10-01), Requarth
patent: 3914978 (1975-10-01), Sekanina et al.
Gustafsson Jan A. K.
Larsson Per-Goran
Jeffers Albert L.
Larson Lowell A.
Niewyk Anthony
Stromsholmens Mekaniska Verkstad AB
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