GB2235410A

GB2235410A - Hydraulic press

Info

Publication number: GB2235410A
Application number: GB9013561A
Authority: GB
Inventors: Wilheim Halbeisen; Bernhard Roken; Heinz Duster
Original assignee: Dorstener Maschinenfabrik AG
Current assignee: Dorstener Maschinenfabrik AG
Priority date: 1989-08-29
Filing date: 1990-06-18
Publication date: 1991-03-06
Also published as: DE3928533C2; GB9013561D0; DE3928533A1; NL9001679A

Abstract

The hydraulic press has a closed frame structure 13 having a front frame 14 and a rear frame 15. The front and rear frames are attached to each other directly by an upper pressing cylinder 1 and a lower pressing cylinder 2 in the region of horizontal frame sections 16 and also by stiffening webs in the form of table mountings 18 for an interchangeable press table 11 in the region of vertical frame sections 17. The assembly constitutes a simple, functional and compact structure. <IMAGE>

Description

A HYDRAULIC PRESS, MORE PARTICULARLY FOR THE BRICKMAKING INDUSTRY This

invention relates to a hydraulic press, more particularly for the brickmaking industryl, having a press frame with an upper pressing cylinder and a lower pressing cylinder for double-acting compaction, guides' for a slide attached to the upper pressing piston and the lower pressing piston, f or an upper tool-piece and a lower tool-piece,, and a press table between the two tool-pieces.

There are known hydraulic presses for the brickmaking industry of this generic type, in which a press frame having cross-pieces is prestressed by tie-rods. The prestressed tie-rod system is intended to avoid expansion in the press frame and skewing of the pressing pistons or tool- pieces. However, this is hardly successful when transverse forces are set up, for example as a result of filling the moulding tools non-uniformly. Moreoverr either the pressing cylinders must be mounted in the press frame with intermediate adapters, or the cross-pieces must be made integral with the pressing cylinders into which the pressing pistons are inserted after complete assembly. This method of construction must be relatively costlyr especially if the presing or moulding table mount is to be interchangeable without loosening the tie-rods and dismantling the press frame. Furthermore, the dead weight of the know embodiments is relatively large and their assembly is complicated.

The object ofthe invention is to devise a hydraulic press, more particularly for the brickmaking industry, of the 1 generic type initially described but distinctly superior thereto in respect of simplicity of design, ease of assembly, compact layoutt functional performance and adaptability to different production conditions.

According to the present inventiong, there is provided a hydraulic press, more particularly for the brickmaking industry, having a press frame with an upper pressing cylinder and a lower pressin 9 cylinder f or doubleacting compaction, guides for a slide attached to the upper pressing piston and.the lower pressing pistony for an upper tool-piece and a lower tool-piece.. and a press table between the two tool-pieces, with the press f rame designed as a closed frame structure having a f ront f rame and a rear f rame, the f ront f rame and the rear f rame being attached to each other directly by the upper pressing cylinder and the lower, pressing cylinder in the region of horizontal frame sections and by stiffening webs in the form of the table mountings for the press table in the region of vertical f rame sections.

The invention arises primarily from the realisation that a closed press frame comprising a front frame and a rear frame, with frame openings to make the working space accessible, ensures symmetrical load distribution during the pressing operations, so that bending and shearing loads are substantially eliminated. Insofar as any expansion compensation is requiredr the pressing cylinders can be advanced further with the aid of an electronic controller, according to the applied pressure and the height of the workpiece or brick.The upper and lower pressing cylinders 1 1 in the press structure of the invention can be held between the front frame and the rear frame directly, with neither adapters nor cross-pieces, as it were themselves acting as cross-pieces. The table mountings make it easily possible to interchange press tables without necessarily dismantling the press f rame. f urthermore#, the table mountings f urther stabilise the press framey because the front frame and the rear f rame support one another in the middle frame region. The front frame and the rear frame constitute steel components in which the frame openings are machined. The hydraulic and driving systems can easily be installed on the press head. The resulting structure is a hydraulic press for the doubleacting compaction process of compact structure, in which is embodied a simple, functionally apt and readily assembled frame constructionr with the added superiority of relatively small weight. The presses of the invention can be delivered ast and assembled from, unitsp but can equally easily be dismantled into individual components.

Further significant features of the invention will now be described. Thus the invention teaches that the pressing piston moving inside the upper pressing cylinder is adapted as a differential ram and the pressing piston moving inside the lower pressing cylinder is adapted as a plunger# two highspeed cylinder-piston sets being associated with the lower pressing cylinder, and the cylinder cross-sections of the upper pressing cylinder on the one hand and the lower pressing cylinder inclusive of the two high-speed cylinders on the other hand being equal. It is within the scope of the 1 invention to dispense with high-speed cylinders for the upper -pressing cylinder, for the rapid advance and retraction of the pressing piston respectively before and after the pressing operation, since the upper pressing piston is adapted as a differential ram and is theref ore capable of both applying the necessary pressing f orces and retracting rapidly. Rapid advance is ensured by the force of gravity, i.e. by the dead weight. The two high-speed cylinders associated with the lower pressing cylinder also contribute to the pressing cycle. However, since the cylinder cross-sections of the upper pressing cylinder and the lower pressing cylinder complete with its high-speed cylinders, it is guaranteed that the applied pressure and compaction rate of the uppe r and lower punchess, i.e.#, the upper tool-piece and the lower tool-piece, are equal during the main compaction process. This ensures satisfactory and unif orm compaction. According to a preferred feature of the invention, the upper and lower pressing cylinders each have a cylinder cover which protrudes into f rame openings of the f ront f rame and the rear f rame, the cylinder covers b eing bolted vertically to the front frame and the rear f ram e. This ensures a uniform load distribution. Even when the press table is f illed non-unif ormly, the transverse forces set up during the production of bricks for example are taken up satisfactorily by the closed press frames, since the compaction forces are transmitted directly through the cylinder covers to the front frame and the rear frame. Moreover, the upper and lower pressing cylinders are satisfactorily set by means characterised in that both 1 pressing cylinders have a polygonal or quadrangular outer contour and are bolted horizontally, on broad faces, to the front frame and the rear frame. In this wayi, one can dispense with additional adapters and cross- pieces, so thaty as already pointed out, the erstwhile high bending and shearing loads are eliminated. The table mountings are pr ef erably bol ted i n pl acej, be tw een th e f ront f ram e and th e rear f rame. In this way, the table mountings become easily inter changeabl ey with the advantage that one can use the widest variety of press tables of different sizes and designs. The forces required to eject the workpieces or bricks are satisfactorily taken up by the front frame and the rear frame. With the known designs, on'the other hand,, there is a risk that the table mountings will become distorted, so that it is seldom possible to remove the press table without dismantling the press frame. In all cases, the vertical frame sections in the design of the invention are adapted as relatively broad sections, so that it is substantially impossible for the front frame and/or the rear frame to buckle or twist. The guides for the guide-pieces of the upper and lower pressing punches are preferably accommodated in the frame openings of the front frame and the rear frame, in the region of the vertical frame sections. In this way, and by virtue of the aforementioned dimensioning of the front f rame and the rear f rame, the guidepieces of the upper and lower pressing punches are prevented from skewing, so that it is impossible for the upper toolpiece and the lower tool-piece to jam, and uniform compaction of the workpieces leads to a superior brick or product 1 1 quality.

The invention will now be described in greater detailt by way of example, with reference to the accompanying drawings in which:- Figure 1 is a schematic f ront elevation of brickmaking press in accordance with the invention; Figure 2 is a schematic side elevation of the press of Figure 1; Figure 3 is a schematic view of the upper pressing cylinder, its pressing piston, and the lower pressing piston; and Figure 4 shows the bolting of the pressing cylinders in schematic side elevation.

The drawings depict a hydraulic press, for the brickmaking industry in particular, basically comprising a press f rame with an upper pressing cylinder 1 and a lower pressing cylinder 2 f or double-action compaction in the manufacture of bricks. Additional components include guides 3t 4 f or slides 7, 8 attached to the upper pressing piston 5 and the lower pressing piston 6, for an upper tool-piece 9 and a lower tool-piece 10. Between the two tool-pieces 9, 10 there is disposed a press table 11. Driving means 12 and hydraulic systems are indicated on the press head. The press frame is designed as a closed f rame structure 13 having a front frame 14 and a rear frame 15. The front frame 14 and the rear f rame 15, which are steel plate weldments, are attached to each other directly by the upper pressing cylinder 1 and the lower pressing cylinder 2 in the region of the 1 horizontal frame sections 16, and by stiffening webs in the form of the table mountings 18 f or the press table 11 in the region of the vertical frame sections 17. The pressing piston 5 moving inside the upper pressing cylinder 1 is adapted as a differential ram, and the pressing piston 6 moving inside the lower pressing cylinder 2 is adapted as a plunger. Two high-speed cylinder-piston sets 19 are associated with the lower pressing cylinder piston 6j, and the cylinder cross-sections of the upper pressing cylinder 1 on the one hand and the lower pressing cylinder 2 inclusive of the two high-speed cylinders 19 on the other hand are equal. The upper and lower pressing cylinders 1, 2 each have a cylinder cover 21, 22 which protrudes into f rame openings 20 of the front frame 14 and the rear frame 15. The cylinder covers 21p 22 are bolted vertically to the f ront f rame 14 and the rear frame 15. Moreovert the upper and lower pressing cylinders 1, 2 have a polygonal or quadrangular outer contour and therefore lie snugly against the horizontal frame sections 16 of thefront frame14 andthe rear frame 15 to which they are bolted horizontally. The table mountings 18 are bolted in place between the f ront f rame 14 and the rear f rame 15, and therefore stand vertically on the insides of the front frame 14 and the rear frame 159, which are thus mutually supported. The guides'3 p 4 f or the slides 7 p 8 of the upper and low er pressing punches are accommodated in the f rame openings 20 of the f ront f rame 14 and the rear f rame 15, in the region of the vertical frame sections 17. The vertical frame sections 17 are made relatively broady to ensure adequate stability 1 against buckling and twisting.

Claims

1. A hydraulic press, more particularly for the brickmaking industry, having a press frame with an upper pressing cylinder and a lower pressing cylinder for doubleacting compaction, guides for a slide attached to the upper pressing piston and the lower pressing piston. for an upper toolpiece and a lower tool-piece, and a press table between the two toolpieces, with the press f rame designed as a closed frame structure having a front frame and a rear frame, the front frame and the rear frame being attached to each other directly by the upper pressing cylinder and the lower pressing cylinder in the region of horizontal frame sections and by stiffening webs in the f orm of the table mountings for the press table in the region of vertical frame sections.

2. A press as in Claim 1, wherein the pressing piston moving inside the upper pressing cylinder is adapted as a differential ramr and the pressing piston moving inside the lower pressing cylinder is adapted as a plunger, two highspeed cylinder-piston sets being associated with the lower pressing cylinder and the cylinder cross-sections of the upper pressing cylinder and of the lower pressing cylinder inclusive of the two high-speed cylinders being equal.

3. A press as in Claim 1 or 2, wherein the upper and lower pressing cylinders each have a cylinder cover which protrudes into frame openings of the front frame and the rear framer the cylinder covers being bolted vertically to the front frame and the rear frame.

4. A press as in any of Claims 1 to 39, wherein the 4 - 10 upper and lower pressing cylinders both have a polygonal#, for example quadrangular, outer contour and are bolted horizontally to the front frame and the rear frame.

5. A press as in any of Claims 1 to 4p wherein the table mountings are bolted in place, between the f ront f rame and the rear frame.

6. A press as in any of Claims 1 to 5, wherein the guides for the slides of the upper and lower pressing punches are accommodated in frame openings of the front frame and the rear frame, in the region of the vertical frame sections.

7. A press as in any of Claims 1 to 6j, wherein the vertical f rame sections are designed as relatively broad sections.

8. A hydraulic pressr more particularly for the brickmaking industry substantially as hereinbefore described with reference to the accompanying drawings.

1 Published 1991 at7bePatcntOfflcc. State House. 66/71 High Holburn London WCIR47P. Further copies may be obtained from Sales Branh. Unit 6. Nine Mile Point, Cwrnfelinfach. Cross Keys, Newport. NPI 714Z. Printed by Multiplex techniques ltd. St Mary Cray. Kent.