A METHOD AND A DEVICE FOR CARRYING OUT VACUUM PRESSING

Abstract: Known vacuum presses exhibit disadvantages in respect of loading and sealing. The constructions are complicated by in spite of this the function is often insufficient. In vacuum pressing according to this invention the sealing of the space, in which vacuum is to be formed, is effected in two steps. The sealing (3) arranged on the device comprises a tongue (3a) and a rim (3b) inside the tongue (3a), preferably with a rectangular cross section.

Description: A method and a device for carrying out vacuum pressing This invention relates to a method and a device for carrying out vacuum pressing. At the vacuum presses used at present loading thereof is often difficult as access to the space to be evacuated requires opening of complicated door arrangements etc. The sealings arranged for the doors are also beset with constructive shortcomings, which is a disadvantage both in respect of function and efficiency. It is the object of this invention to. provide a vacuum press where the deficiencies mentioned above have been eliminated. This is done by means of a method and a device with the characteristic features set forth in the following claims. An illustrative example of the invention will be described below with reference to the enclosed draw¬ ings, where Fig. 1 shows a device according to the invention; Fig. 2 shows on a larger scale a section of an edge portion of the device according to Fig. 1 , and Figs. 3 - 5 show another embodiment of devices according to the invention. The vacuum press shown in Fig. 1 comprises an upper unit 1, which is supported by four frame legs 2. The upper unit 1 comprises a press plate 1 a along the edges of which a sealing 3 is arranged, which will be described more thoroughly with reference to Fig. 2, where it is shown more in detail. As is also evident from Fig. 1 the press has two cassettes 4 a and 4 b, which are supported by legs 5 a and 5 b provided with wheels and guided along rails 6 a and 6 b on the floor. The cassettes 4 a, 4. b have a space inside their frame 7, where the article to be vacuum-pressed is placed. The loaded cassette is then pushed in under the press plate 1 a to the position taken by the cassette 4 b in Fig. 1. As the two sets of wheeled legs S a and 5 b have a different length the cassettes 4 a and 4 b will be on different levels and, moreover, as the legs 5 a are placed more closely to each other than the legs 5 b, the cassettes 4 a and 4 b can be moved past each other. When the cassette 4 b has entered the position shown in Fig. 1 the cylinders 8, which are preferably pneumatically operated, are activated, and press the cassette 4 b to contact with the sealing 3, after which the space between the cassette 4 b and the press plate 1 a inside the sealing is evacuated by means of a vacuum pump with ordinary peripheral equip¬ ment (not shown) . When the article in the evacuated space has been exposed to vacuum pressing by the press plate 1 for a sufficient time the negative pressure is balanced and the cassette 4 b is lowered until it rests on the floor, after which it is moved away from the press plate 1 along the rails 6 b. While the article in the cassette 4 b has been vacuum pressed the cassette 4 a has been loaded with a new article to be exposed to vacuum pressing. As soon as the cassette 4 b has been removed the cassette 4 a is introduced under the press plate 1 a, after which the same procedure as with the cassette 4 b is repeated. It is apparent from the detail shown in Fig. 2 that the sealing 3 is arranged on a profile 9 of the upper unit 1 and lies close to the frame 7 of the cassette 4 a or 4 b. OM WII The sealing 3 which, as pointed out above, is an extraordinarily important constructional detail of the present invention, is of a double-acting type. This is expressed in the fact that the sealing has an outer, very shapeable tongue 3 a, which at displacement of the cassette from below upwards towards the press plate 1 will first come into contact with the frame 7 of the cassette 4 a or 4 b. At additional raising of the cassette 4 a or 4 b towards the press plate 1 a the inner sealing 4 b preferably consisting of a square rim of resilient material will also come into contact with the frame 7. After the tongue 3 a has come into contact with the frame 7 and vacuum has been applied the frame 7 is lifted further towards the rim 3 b by the vacuum between the press plate 1 a and the cassette 4 a or 4 b. The outer to-ngue 3 a can e.g. consist of a homo¬ geneous rubber material, while the square rim 3 b can consist of e.g. cellular rubber. An extraordinarily reliable sealing against the frame 7 of the cassette 4 a or 4 b is obtained by the double-acting sealing rim 3, which thus operates in two steps. As is also apparent from Fig. 2 the press plate 1 a is articulatedly connected to the profile 9 via a plate 10, the longitudinal edge portions of which are made in recesses 11 and 12 respectively in the profile 9 and in a rim 13 disposed on the press plate 1. In order to retain the plate in the recesses 11 and 12 a flexible cloth 14 preferably made from rubber is adapted on the upper side of the plate, which cloth is connected with the upper sides of the profile 9 and the rim 13. When a vacuum is formed in the space between the cassette 4 a or 4 b the press plate 1 a this will thus move downwards to come into contact with the article which- is in the space and is to be subjected to pressing. In Fig. 3 an embodiment of the press according to the invention is shown, where the poles 2' support¬ ing the press plate 1 a are arranged at the corners of the press plate 1 a. In this way it is possible to insert the cassettes 4 a or 4 b from all four directions, as indicated by the arrows. It is also clearly evident from Fig. 3 how the sealing rim 3 runs along the edges of the press plate 1 a. In Fig. 4 an embodiment of the invention is shown, where four press plates 1'a have been adapted on a rotatable frame 15, which is suspended in support legs 16. In one suspension point of the frame 15 a" drive means 17 is arranged, which in¬ cludes an electric motor in the illustrative example. On the support legs 16 lifting arms 18 are also arranged, which lift the cassette 4' to make contact with the sealing 3 r of the lowermost press plate 1'a, after which a vacuum can be formed in the space between the cassette 4 and the press plate 1'a. However, for safety reasons only the negative pressure formed ' cannot hold the cassette 4' against the press plate 1'a but additional securing is necessary which, however, is not shown in the igure. After the article placed in the lowermost cassette in Fig. 4 has been subjected to vacuum pressing for a sufficient time the cassette is transferred to a conveyor 19 a which brings the cassette further to the next station of treatment. OM WI As soon as the finished cassette has been removed a loaded cassette 4' is transferred via a conveyor 19 b to the arms 18, after which lifting and securing of the cassette 4' against the press plate 1'a are effected with accompanying formation of a vacuum in the space between the cassette 4' and the press plate 1 'a. The frame 15 is then rotated a quater of a revolution, after which the procedure described above is repeated. In Fig. 5 a frame 15' with six press plates 1" a is shown. As distinguished from the device according to Fig. 4 feeding and discharge of the cassettes are carried out here on the long sides of the press plates 1"a. A drive means (hidden) for the rotation of the frame is arranged on the inside thereof as well as a compressor 20. To use, as shown at the devices in Figs. 4 and 5, in a rational way several press plates it is conse¬ quently possible to increase the production rate in comparison with the device shown in Fig. 1. Of course a plurality of other devices adapted to production are possible for utilizing the original inventive idea. Thus, the invention is by no means restricted to the illustrative examples shown above but can be freely varied within the scope of the following claims.

Claims: PATENT CLAIMS • 1. A method for carrying out vacuum pressing, characterized in that the article to be vacuum-pressed is received in a cassette (4; 4'), after which an edge, portion (7) of the cassette is brought into contact from below with a sealing (5) adapted on a fixed frame (9) and ' that a vacuum is thereafter formed between the cassette (4; 4') and the frame (9) so that a press plate (la) movable relative to the frame (9) is brought to exert a press pressure on the article in the cassette (4;4'). 2. The method of claim 1, characterized in that when the cassette (4; 4a) is brought into contact with the frame (9) a .first sealing is achieved in such a • way that a tongue (3a) of the sealing (3) will come into contact with the frame (9) and that a rim (3b) will thereafter come into contact with the frame (9) to secure final sealing. 3. A device for effecting vacuum pressing according, to claim ' 1 or 2, comprising means to form a negative pressure in a closed space, characterized in that it ■ comprises one or more fixed frames (9) , on which a sealing (3) is arranged, a press plate (1a; 1'a; 1"a) associated with each frame (9) , movable relative to this and substantially air-tightly connected with the ' frame (9), one or more cassettes (4;4') having an edge rim (7) , which is intended to lie close to the sealing (3) of the frame (9) in the active position of the device, and means for lifting and retaining the cassette (4; 4') against the frame (9). 4. The device of claim 2, characterized in that the sealing (3) comprises a tongue (3a) of resilient material and a rim (3b) lying inside the tongue (3a) and also made from a resilient material. OM " 5. . The device of any of claims 2 - 4, characterized in that the press plate (1a) is articύlatedly attached to the frame (9) and movable perpendicularly to the main plane thereof, the articulated attachment comprising a recess (11; 12) arranged on the frame (9) and on the press plate (1a), in which the ends of a disc (10) are received, hich are retained in the recesses (11; 12) by means of a flexible cloth (14) extending on the side of the disc (10) turned from the recesses (11; 12), the end portions Of said cloth being attached in connection with the recesses (11; 12). 6. The device of any one of claims 2 - 5, characterized in that a plurality of press plates (1'a; 1"a) are ' arranged on a rotatable stand (15).

Inventors: SUNDSTROEM B
Applicants: LOEOEVEVERKEN AB, SUNDSTROEM B
Application year: 1979
Main classification: B29C17
IPC codes: B29C43, B30B1