EP0111530B1

EP0111530B1 - Fixing device

Info

Publication number: EP0111530B1
Application number: EP83901954A
Authority: EP
Inventors: Borislav Simic
Original assignee: Individual
Current assignee: SIMIC Borislav
Priority date: 1982-06-07
Filing date: 1983-06-06
Publication date: 1987-04-22
Also published as: SE443316B; SE8203517L; EP0111530A1; JPS59501053A; DE3371048D1; WO1983004384A1

Abstract

A fixing device intended for securing substantially plane objects. The construction comprises a plate or the like which is provided with a plurality of vacuum cells (18) arranged in a predetermined, spaced relationship to each other. The vacuum cells can be connected to a common vacuum source via air channels made in the plate. The plate comprises especially a base element (10), in one surface of which the vacuum cells are made with connection to the respective air channels inside said surface, and a covering element (14) in the form of an elastic disc or the like, which has membrane function, an object being placed against the covering element bearing against said one surface of the base element.

Description

This invention relates to a fixing device with a plurality of vacuum cells, each capable of being connected to a vacuum source common to the cells via at least one air channel formed in the device, the vacuum cells being recesses in a base element, over which an elastically deformable covering element is arranged, against which preferably plane objects are intended to be secured.
Fixing devices of said kind are previously known, e.g. a mat of rubber or a rubbery material being provided with a plurality of openings, which are in a communicating connection with the vacuum source. A negative pressure arises in the openings covered by the workpiece when the vacuum source is connected, the workpiece being fixed in its position. Depending on the shape and size of the workpiece it is however not certain that all the openings in the mat are always covered. Thus, the openings not being covered or only partly covered by the workpiece provide an open connection between the vacuum source and the atmosphere. Therefore a fixing device made according to these principles requires a large working volume of air and consequently also a great pump capacity for securing objects. This makes great demands on the utilized pump equipment and brings essential costs.
It is also known to arrange in connection with each vacuum cell a sealing means, the connection between the respective vacuum cell and the vacuum source including a valve means with an actuating means which is activated to connect the respective-vacuum cell with the vacuum source only when the vacuum cell is completely covered by the object. However, the valve arrangement associated with this known fixing device comprises both balls and springs, which makes the construction very complicated. The use of these and similar valve arrangements also brings the risk of a wrong function due to clogging, as particles in the form of chips and the like often occurring in close proximity to the fixing device can easily penetrate the sensitive interior portions of the construction.
DE-A-2 942 876 shows a fixing device having a valve mechanism in the form of an opening in an elastically deformable covering element. Said opening is provided to be closed against a seat in the form of a recess of a body. However the orifice connected to the air passage and the recess is so arranged that impurities or other particles easily can be sucked into said orifice and cause operational disturbances.
It is now the object of the invention to provide a fixing device, the construction of which is simple and which comprises the least possible number of clogging components. Moreover, the construction should be embodied so that possible impurities occurring in its air channels and air ways in the form of particles, e.g. chips, can be easily removed without unnecessary waste of time. Another object of the new construction is that it should be capable of operating with the least possible vacuum so that relatively simple vacuum equipment can be utilized.
A fixing device of the kind mentioned above satisfying the demands made is according to the invention characterized in that an orifice of the respective air channel is formed by a raised portion of the respective recess and forms a seat of a membrane valve, whose membrane, which can be moved from a closing position, is farmed from a part of the covering element, and that the covering element is provided with passing openings which maintain a communicating connection with the interior of the vacuum cell when the membrane valve is closed as well as when it is open.
The invention is described below more in detail in the form of some preferred illustrative examples with reference to the enclosed drawing.

Fig. 1 is a perspective view of the main features of a fixing device, which is made according to the principles of the invention.
Fig. 2 is a lateral view of a section of a plate which can be included in the fixing device illustrated in Fig. 1.
Fig. 3 shows-a top view ofthe portion illustrated in Fig. 2.
Fig. 4 shows a lateral sectional view of a portion of a plate made as an alternative, which can be included in the fixing device illustrated in Fig. 1.
Fig. 5 shows a top view of the portion illustrated in Fig. 4.

The fixing device illustrated in Fig. 1 consists of a plate, which is composed of a base element 10 with rectangular sides and a covering element 14 articulatedly connected to this at one long side 12. The covering element is dimensioned to cover the upper surface of the base element completely when it bears against the same.
The base element 10 manufactured as a block of metal, hard plastic or the like comprises a great number of air channels partly ending in a common connection means 16 located at one side of the block and intended for connection to a vacuum source not shown, and partly in the respective vacuum cells 18 made at the upper side of the base element.
The covering element 14, which is articulatedly connected to the base plate 10 along said one long side 12 by means of hinges, gluing or in another way, is elastic and easily deformable so that it can operate as a membrane. The covering element preferably consists of a rubber disc which can have a thickness of e.g. 3-5 mm, or of a steel disc which can have a thickness of e.g. 0.5 mm. The thickness relations are of course variable. However, what is essential is that the disc is capable of being resiliently deformed in connection with the evacuation of the vacuum cells 18.
The fixing device can have many different uses. Thus, it can e.g. be a supporting element on a workbench for retaining workpieces. It can also be used in connection with a lifting device for retaining objects. In the latter case the placement of the plate in the room can be reversed to what applies to its use on a workbench.
In Figs. 2 and 3 one single vacuum cell 18'as wei) as surrounding parts of a plate according to Fig. 1 are shown. An air channel 20 leading from the vacuum cell to a channel 22 common to additional similar air channels is illustrated in the base element 10'. The vacuum cell 18' is made at the upper surface of the base element 10' and the air channel 20 ends at an annular section 24 projecting past the bottom 26 of the vacuum cell but terminating somewhat below the upper surface 28 of the base plate. The fixing device is illustrated in its working position, i.e. when the covering element 14' bears against the upper surface 28 of the base element 10'. However, no working piece has still been placed on the covering element. In connection with the vacuum cell 18' there is a plurality of similar holes 30 through the covering element outside the extension of the defining surface of the air channel 24. The holes 30 are very fine and their number is not critical for the relative purpose.
The arrangement according to Figs. 2 and 3 is such that the vacuum cell 18' at connection to the vacuum source via said air channels 20 is exposed to a relatively rapid air stream in immediate connection with the orifice 32 of the air channel whereas the air stream will have a slower course at the bottom 26 of the vacuum cell. This has the effect that possible particles in the form of chips and the like unintentionally passing into the vacuum 18' are collected at its bottom 26 and are prevented from being moved up to and down through the air channel 20. Thus, the vacuum cell serves as a so-called particle trap. At a heavy suction through the air channel 20 the portion of the covering plate 14' located above the orifice 32 thereof is pressed downwards so that the air channel 20 is blocked at the orifice 32. If a plane object not being too pervious to air is placed on top of the covering element 14' this object prevents air from passing through the holes 30 of the covering element 14' which has the effect that a vacuum is created in the vacuum cell 18'. Due to coaction between a plurality of such vacuum cells an object (not shown) placed on top of the covering element 14' will be fixed in the intended position with a great force. As vacuum cells located outside the defining surface of the object have the connections with the respective channels closed by means of the portions of the covering element 14' serving as membrane a vacuum pump utilized to this end need not have so great a power to fulfil its purpose.
The embodiment of a plate illustrated with reference to Figs. 2 and 3 is especially suitable for securing substantially plane objects which can be somewhat air permeable. If the objects are compact and do not let any air pass at all, the same demands, however, are not made on the fixing device. This can in that case, e.g. as far as object of the type plastic film and the like are concerned, be made in a somewhat simpler manner in such a way that the covering element can lack holes completely.
In the embodiment of the plate illustrated in Figs. 4 and 5 the vacuum cell 18'" is deepest in connection with the front end of a corresponding flap 36, which is cut in the covering element 14"'. As is apparent from Fig. 4 an object 38 is placed so that it covers one of the vacuum cells 18"' shown, whereas another similar vacuum cell is outside the limiting line of the object. When the vacuum source is connected the flap 36 closes the air channel 40 so that no air passes from the atmosphere. However, the other flap does not reach completely down to the orifice 32'" of the air channel, resulting in that the vacuum cell will have a negative pressure so that the object 38 "is sucked fast". As the air channels 40, like at the embodiment according to Figs. 2 and 3, are above the bottom 26"' of the vacuum cells particles passing into these will possibly be left in the bottom regions. The air channels 40 ending in the vacuum cells 18'" are joined at the opposite ends in a common channel 42, which leads out at one side of the block for further connection to the vacuum source not shown.
In all the embodiments of the plate shown a possibility is offered to clean the vacuum cells with compressed air. In the embodiment according to Figs. 2 and 3 this is carried out by lifting the coveri-ng element 14' to some extent, after which the working direction of the vacuum pump is reversed so that air passes through the air channels 20 towards the-vacuum cells 18'. Through the positive pressure arising at the orifices of the air channels the air "bounces" via the covering element towards the bottom regions of the vacuum cells so that possibly occurring particles are blown away there. The cleaning process can be carried out very effectively and quickly.
In the embodiment according to Figs. 3 and 5 special feeding channels 44 from the vacuum source are used - although not absolutely necessary - to clean the vacuum cells 40. Otherwise cleaning is carried out in the way previously described.
Additional modifications of the fixing device described above are possible within the scope of the following claims.

Claims

1. Fixing device with a plurality of vacuum cells (18), each capable of being connected to a vacuum source common to the cells via at least one air channel (20, 40) formed in the device, the vacuum cells being recesses in a base element (10), over which an elastically deformable covering element (14) is arranged, against which preferably plane objects are intended to be secured, characterized in that an orifice (32) of the respective air channel (20) is formed by a raised portion of the respective recess and forms a seat of a membrane valve, whose membrane, which can be moved from a closing position, is formed from a part of the covering element (14), and that the covering element (14) is provided with passing openings (30) maintaining a communicating connection with the interior of the vacuum cell, when the membrane valve is closed as well as when it is open.

2. The device of claim 1, characterized in that the orifice (32) of each air channel (20) is located in the centre of the respective vacuum cell (18').

3. The device of claim 1, characterized in that the covering element (14"') is provided with slots in connection with its portion adjacent the respective vacuum cell (18"") in said working position and that the slots define flaps (36) which can be actuated by air and are located immediately outside the orifices (32"') of the respective air channels (40) in the vacuum cell.

4. The device of claim 3, characterized in that the bottom of the vacuum cell (18"') is located within and in connection with the front edge of the flap (36).

5. The device of any of claims 1-4, characterized in that the covering element (14) is detachable from the base element (10).