Press, especially for deburring a workpiece

Abstract

Press (10), in particular for machining, such as deburring, workpieces, comprising at least one press device with a press cylinder (24) having a press piston rod (22) and a hold-down cylinder (32) with a hold-down piston rod (40), wherein the press piston rod is connected to a holder (20) for a tool via a flange plate (26), characterized in that the workpiece-side end face (28) of the flange plate (26) of the press piston rod (22) has a passage opening (52) which can be passed through by the hold-down cylinder (32) integrated in the press piston rod (22), the hold-down cylinder housing (42) of which is inserted in a blind opening (36) extending from the workpiece-side end face (34) of the press piston rod (22).

Description

[0001] The invention relates to a press, in particular for deburring a workpiece, comprising at least one press device with a press cylinder having a press piston rod and a hold-down cylinder with a hold-down piston rod, wherein the press piston rod is connected to a holder for a tool via a flange plate.

[0002] Presses can be used to manufacture or process workpieces, such as deburring. Examples of suitable presses can be found in DE 27 53 360 A1, DE 10 2005 029 060 B3, or EP 3 820 635 B1.

[0003] The presses can have an upper plate, called a yoke plate, positioned at a fixed distance from a tabletop onto which a workpiece is attached. A press cylinder extends from this plate and is connected to a press plate, usually called a ram, which is guided along columns and adjusted towards the tabletop to perform the pressing operation.

[0004] To ensure that the workpiece is fixed in a precise position relative to the tool extending from the ram, a hold-down device may be provided, which is typically arranged below and connected to a piston rod of the press cylinder. In this respect, reference is made to DE 40 32 456 A1 by way of example.

[0005] Because the hold-down device, which is usually a hydraulic cylinder, runs below the press piston rod, the resulting presses have a large overall height, which can be as high as 8 m, for example, requiring appropriate structural measures for setting up the presses.

[0006] The subject of JP 2015-147224 A is a hydraulic press having two pistons, with a main piston connected to a cylinder of a second piston.

[0007] A forging press according to DE 10 2016 103 927 A1 has two cylinders designated as primary and secondary drives. The cylinder of the secondary drive extends partially into the piston of the primary drive.

[0008] A double cylinder arrangement with a main cylinder and an ejection cylinder can be found in CN 101712207 A.

[0009] A hydraulic press according to JP-07098004 A has a main cylinder and a piston designated as a lower cylinder, which is intended for deburring.

[0010] The present invention is based on the objective of further developing a press of the aforementioned type in such a way that a compact design is achieved, whereby a trouble-free replacement of the hold-down cylinder should be possible.

[0011] To solve the problem, the invention essentially provides that the workpiece-side end face of the flange plate of the press piston rod has a through-opening which can be penetrated by the hold-down cylinder integrated in the press piston rod, the hold-down cylinder housing of which is inserted in a blind opening extending from the workpiece-side end face of the press piston rod.

[0012] In contrast to the prior art, the hold-down cylinder is not located below the press cylinder, but integrated into it or into its piston rod. Thus, a blind hole can extend from the table-side, i.e., workpiece-side, end face of the press piston rod, in which the hold-down piston or hold-down piston rod is, for example, removed.

[0013] However, according to the invention, the hold-down cylinder housing is inserted into the recess of the hold-down piston rod. This allows for easy replacement without having to remove the press piston rod itself.

[0014] Integrating the hold-down cylinder into the press piston or press piston rod significantly reduces the overall height of the press compared to prior art designs where the hold-down cylinder is located below the press cylinder. Height reductions of up to 20% are readily achievable.

[0015] Furthermore, it should be emphasized that the press cylinder is a single-acting cylinder, in particular a plunger cylinder.

[0016] A plunger cylinder, also known as a reciprocating piston cylinder, does not have a conventional piston. Instead, the piston rod itself acts as the piston. Plunger cylinders have a favorable mechanical efficiency.

[0017] The press piston rod itself, or in the case of a plunger cylinder, the piston, should be connected via the flange plate to the workpiece-side section of a ram, whereby the workpiece-side surface of the flange plate should be aligned with the surface of the ram facing the table. These design features significantly reduce the overall height compared to conventional presses.

[0018] By integrating the hold-down cylinder into the press piston rod and thereby enabling the press piston rod to be connected to the adjustable plunger in such a way that the required fastening runs in the area facing the table top, a reduction in overall height is achieved compared to known presses, such as those described in DE 40 32 456 A1.

[0019] The plunger, from which the tool required for machining or deburring extends, should be guided over four guide columns, with drive devices for adjusting the plunger being assigned to two diagonally opposite, and in particular exclusively to two diagonally opposite, guide columns, which are designed in such a way as to enable a quick return of the plunger to the starting position.

[0020] Each drive unit should ideally be a hydraulic cylinder, but can also be designed as an electromechanical actuator.

[0021] The time for the ram movement up and down in rapid traverse is a significant part of a complete machining cycle and should therefore be between 1:4 and 1:7 in relation to the time of the pressing process.

[0022] The piston surfaces of the press cylinder and the drive cylinder of the drive unit are designed accordingly.

[0023] The same boundary conditions apply to the implementation with electromechanical actuators.

[0024] Appropriate drive mechanisms enable a rapid adjustment of the plunger.

[0025] The drive mechanisms not only make it possible to quickly return the plunger to its starting position, but also to quickly move it towards the workpiece in order to then carry out the actual machining or deburring process via the press cylinder.

[0026] To ensure that a vacuum does not build up in the press cylinder when the ram is quickly lowered, a suction valve is provided in the supply line to the press cylinder.

[0027] Furthermore, the invention is characterized in that the drive device is assigned a fall protection device which, in the case of a differential cylinder, surrounds the piston rod and should be based on the principle of mechanical friction or clamping.

[0028] However, it is also possible, if necessary additionally, to provide fall protection along the columns to which drive devices are not assigned.

[0029] The fall protection device in question may be one distributed by SITEMA-Gesellschaft für Sicherheitstechnik und Maschinenbau mbH. This type of fall protection works primarily through mechanical friction and / or clamping.

[0030] To enable trouble-free removal of the hold-down cylinder, it is provided that the flange plate connected to the workpiece-side end face of the press piston rod, which is connected to the plunger, has the through-opening that can be passed through by the hold-down cylinder housing inserted in the press piston rod.

[0031] Furthermore, channels carrying pressure medium should run in the flange plate to the hold-down cylinder.

[0032] In order to avoid further machining on the press piston rod of the press cylinder next to the recess required for receiving the hold-down cylinder, it can also be provided that pressure medium channels required for actuating the hold-down cylinder run in the housing of the hold-down cylinder.

[0033] Further details, advantages and features of the invention will become apparent not only from the claims and the features to be derived therefrom - individually and / or in combination - but also from the following description of a preferred embodiment.

[0034] They show: Fig. 1 in principle a press and Fig. 2 in the cutout a press piston rod with integrated hold-down cylinder.

[0035] Based on the principle diagrams according to Fig. 1 and Fig. Section 2 will explain the teaching according to the invention, which relates to a press for processing, in particular deburring, a workpiece. If deburring is the preferred application of the press, it can also be used, for example, for cutting, compressing, or chipless forming of workpieces.

[0036] In accordance with conventional presses that can exert pressing forces of up to 300 tons, the press 10 has a frame 11 with a table top 12 attached therein and an upper stationary plate, which is referred to as a yoke plate 14 and which is connected to the table top 12 by means of usually four guide columns forming the corners of a rectangle or square, two of which are shown and marked with the reference numerals 16, 18.

[0037] Along the guide columns 16, 18, a holder for a tool, designated as a plunger 20, is adjustable, from which a tool (not shown) extends for machining a workpiece arranged on the table top 12.

[0038] In particular, the workpiece is a casting that needs to be deburred.

[0039] The ram 20 is connected to a piston rod 22 of a press cylinder 24, which is in particular a plunger cylinder. The press cylinder 24 extends stationary from the yoke plate 14. The piston rod 22 is connected to the ram 20 via a flange plate 26. As shown in the drawing, the Fig. 1 the workpiece-side, i.e. table-top-side surface 28 of the flange 26 in the area of ​​the workpiece-side area of ​​the plunger 20.

[0040] In particular, the workpiece-side surface 28 is flush or almost flush with the workpiece-side surface 30 of the plunger 20 or with a plane spanned by the workpiece-side area of ​​the plunger 20.

[0041] To fix the workpiece arranged on the table top 12 in order to be able to carry out machining or deburring, a hold-down device is provided in a known manner, which according to the invention is a hold-down cylinder 32 that is integrated into the press piston rod 22, as can be seen in particular from the detailed illustration according to Fig. 2 results.

[0042] For this purpose, a preferably stepped recess 36 extends from the workpiece-side end surface 34, which runs as a table-side, into which the hold-down cylinder 32 can be inserted, which should be a differential cylinder with piston 38 and piston rod 40.

[0043] The cylinder housing 42 of the hold-down cylinder 32 is connected to the press piston rod via a ring flange 44.

[0044] The end face 34 of the piston rod 22 is also connected to the flange plate 26, which in turn is connected to the plunger 22. A bore 48 for a fastening screw is shown for illustrative purposes only. Another bore 50 for a fastening screw to the piston rod 22 is also shown.

[0045] The flange plate 26 has a central through-opening 52, the diameter of which is such that the hold-down cylinder 32 can be removed from the press piston rod 22 or inserted into the opening 36 without removing the flange plate 26.

[0046] Channels 54 and 56 run through the flanges 26 and 44 and in the housing wall of the hold-down cylinder housing 42 to actuate the differential cylinder, i.e., the hold-down cylinder 32. This is self-explanatory and also follows from the schematic diagram of the Fig. 2.

[0047] The pressure medium connection for the plunger cylinder 24 is located in the end face 58 of the piston cylinder housing 60, facing away from the table top. A suction valve is provided in the supply line.

[0048] To enable the press to open, i.e., to retract the ram 20, drive units are provided, one of which is located in the Fig. 1 is shown and is designed as a differential cylinder 62. According to the invention, two corresponding drive units 62 are provided, which run along diagonally opposite guide columns, one of which is marked with reference numeral 18.

[0049] Furthermore, at least one fall protection device 64 is provided, which in the exemplary embodiment runs along one of the guide columns to which a drive unit 62 is not assigned. In the exemplary embodiment, a corresponding fall protection device 64 runs along column 16.

[0050] In particular, it is provided that two fall protection devices 64 are present along the diagonally opposite guide columns, along which the drive units do not extend.

[0051] The drive units 62 enable rapid opening of the press 10. Adjustment of the ram 20 towards the worktable 12 before the pressing or deburring process is also possible via the drive units 62. Due to the significantly smaller cross-section of the piston of the differential cylinder 62 compared to the cross-section of the press piston rod 22, a rapid traverse is effectively provided.

[0052] The teaching according to the invention results in a total height of the press that is considerably lower than that of known presses of the same pressing force compared to the prior art, so that corresponding structural measures can also be reduced.

[0053] By using the press cylinder 24 in the form of a plunger cylinder, a structurally uncomplicated drive type is provided, whereby a thick-walled tube can be used as the housing 60.

[0054] The integration of the hold-down cylinder 32 into the press cylinder 24 or the piston rod offers not only an advantage in terms of the overall height of the press 10, but also design simplifications.

[0055] Rapid opening is achievable because, when differential cylinders are used as the additional drive units, pistons are employed that have a far smaller piston area compared to presses where the press cylinders are designed as differential cylinders, which are used to both close and open the press.

[0056] Two hydraulic movements can be performed simultaneously: those of the drive unit(s), particularly in the form of the differential cylinders, and those of the press cylinder. These movements can overlap when the press closes, resulting in faster closing.

[0057] The cylinders are hydraulic cylinders.

[0058] Typical dimensions of presses according to the invention are, without limiting the invention: - Press height: approx. 8000 mm, with a 3000 mm installation height and a 2000 mm stroke - Press width: approx. 3000 mm clear span between columns - Press depth: approx. 3000 mm clear width between columns - Cross-sectional area of ​​the press piston rod: approx. 1050 cm 2 - Cross-sectional area of ​​hold-down piston rod: 20 cm² 2 - Piston area of ​​the hold-down device: 64 cm² 2 - Piston of the drive unit: 115 cm 2 - Piston rod of the drive unit: 78 cm 2 - Pressing forces: when opening the press (lifting forces) approx. 25 t (times 2 = 50 t with 2 drive units)

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