EP0015950B1

EP0015950B1 - Device for stretching a cloth on a frame for fixing the cloth thereto in the stretched condition

Info

Publication number: EP0015950B1
Application number: EP79900407A
Authority: EP
Inventors: Gösta WADSTEIN
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-04-18
Filing date: 1979-11-19
Publication date: 1982-06-16
Also published as: JPS55500238A; IT1116028B; WO1979000939A1; CH642304A5; IT7948771A0; GB2036118A; DK523479A; EP0015950A1; SE409674B; GB2036118B

Abstract

A device for stretching and fixing a cloth (25) on a frame comprises a stand (11) with a rectangular border (12), a bottom (13) and an underframe (14). On the bottom an inflatable pad (19) is arranged, against which a pressure plate (23) rests. The pressure plate is somewhat smaller than the border (12) of the stand and is moveable in relation to that and adjustable into different angles relative to the bottom (13). A clamping device (16) can be placed above the border (12) and is by tightening means (15) pressed against the stand (11), thereby clamping the cloth (25) against the border.

Description

Background of the invention

The present invention refers to a device for stretching a cloth on a first frame for fixing the cloth thereto while in the stretched condition, comprising a main frame, a clamping device for clamping the cloth on all sides to the main frame, the main frame surrounding a plate supporting the first frame and movable by a member relative to the main frame for displacing the plate and first frame in a direction to stretch the cloth.
When mounting cloths of the above mentioned kind it is important that the cloth is stretched regularly over the whole surface area. For small frames the stretching and fixing have been made manually and inevitable irregularities following such a manual operation had to be tolerated. For large frames including several square metres pneumatic frame stretching devices have been used, which by means of a great number of pneumatic stretching means stretches the cloth until the sufficient stretching force is obtained. With these machines a good result is obtained, but the fixing of a great number of stretching means is difficult and very time-requiring. Moreover such machines are very expensive and requires a large space. An example of such a device is described in the Swiss patent specification 402 . 790.
In the German Auslegeschrift 2 . 020 . 958 is described a device of the kind mentioned in the introduction, which however has certain drawbacks. Thus the pressure plate can be displaced only perpendicular to the guides in the frame. By reason of that the pressure plate cannot compensate possible irregularities of the stretching of the cloth against the frame.
In the US patent specification 1 . 778 . 385 a device for stretching a skin against a stencil is described, in which pneumatic pads are used. The purpose is to make the stencil lie tightly against the skin, thus avoiding that the dye or other colouring material used is running underneath the stencil. This device is accordingly intended for a quite different purpose and for a different technical field than the device according to the invention.

Description of the invention

The purpose of the present invention is to provide a device, which facilitates the procedure of stretching and fixing the cloth and which by simple means and at a reasonable price gives a perfect result. It is an important condition that the pressure plate can be adapted also to irregularly mounted cloths.
This has according to the invention been achieved by the fact that the main frame is provided with a bottom, the member is a pad inflatable with a fluid and positioned between the plate and the bottom of the main frame, the plate is sufficiently smaller than the inside dimensions of the main frame to allow the plate to tilt relative to the bottom, and that the clamping device comprises a further frame pressable by tightening means against the main frame with the cloth there between.

Description of the drawings

The invention will now be further described with reference to an embodiment shown in the accompanying drawing.

Figure 1 is a plane view of the device according to the invention, and
Figure 2 is a section according to the line 11-II in figure 1.

Description of an embodiment

The stretching and fixing device according to the invention comprises a box-shaped main frame 11 comprising a rectangular border 12, a perforated bottom plate 13 and an underframe 14. A clamping device 16 can by means of tightening means 15 be pressed against the upper edge of the border 12, which is made of square tubes.
The clamping device 16 comprises a frame of substantially the same size as the border 12, said frame also being made of square tubes on the pressure surfaces of the clamping device 16 and the border 12 facing and cooperating with each other a friction lining 17 and an elastic pressure lining resp. or vice versa are attached.
On the perforated bottom 13 of the main frame 11 an expandable member 19 is placed, which according to the embodiment shown comprises a pneumatic pad of a plastic or rubber material. The inflation and the discharge of air can be made by way of a flexible tube 20 connected with a pressure gauge 21 and a stop valve 22. A pressure plate 23 rests against the pad 19, said pressure plate extending over a substantial part of the free space between the side edges of the border 12.
The cloth is stretched and fixed in the following way. A frame 24 over which a cloth 25 is to be stretched is placed substantially in the middle of the pressure plate 23 and the cloth 25 is uncoiled from a supply roller 26 and is widened over the frame 24 and over the edge of the border 12. At this initial working moment the clamping device 16 is removed and the air is evacuated from the pad 19. After having placed the cloth over the frame 24 and the border 12 of the main frame the clamping device is placed on the cloth 25 just opposite the upper edge of the border and the tightening means 15 are tightened, so that the clamping device 16 is pressed against the border and an effective fixing of the cloth 25 is achieved. Then the pad 19 is inflated to an appropriate pressure, which can be read on the pressure gauge 21. When the pad 19 is expanded the pressure plate 23 with the frame 24 will be pressed against the fixed cloth 25 and if this is irregularly fixed the pad will compensate such irregularities, so that an absolute regular stretching is achieved.
At very large stretching and fixing devices several pneumatic pads could be used, or the pad could be divided into a number of sections communicating with each other.
The invention is not limited to the embodiment described above and shown in the drawing, but a number of variations are possible within the scope of the claims. Thus the tightening means 15 of the clamping device 16 can be of another type, e.g. pneumatically or hydraulically operated.

Claims

1. A device for stretching a cloth (25) on a first frame (24) for fixing the cloth thereto while in the stretched condition, comprising a main frame (11), a clamping device (16) for clamping the cloth (25) on all sides to the main frame (11), the main frame (11) surrounding a plate (23) supporting the first frame (24) and movable by a member (19) relative to the main frame (11) for displacing the plate (23) and first frame (24) in a direction to stretch the cloth (25), characterized in that the main frame (11) is provided with a bottom (13), the member (19) is a pad inflatable with a fluid and positioned between the plate (23) and the bottom (13) of the main frame (11), the plate (23) is sufficiently smaller than the inside dimensions of the main frame (11) to allow the plate (23) to tilt relative to the bottom (13), and that the clamping device (16) comprises a further frame pressable by tightening means against the main frame (11) with the cloth there between.

2. A device according to claim 1, characterized in that the pressure surfaces of the clamping device (16) and the main frame (11) cooperating with each other are provided with a friction lining (17) and an elastic pressure lining (18) resp.

3. A device according to claim 1 or 2, characterized in that the pad (19) is inflated by pressure air, is made of a plastics or rubber material, and is divided into a number of compartments communicating with each other.