GB2047600A - A washer-punching and transfer device - Google Patents

Abstract

A device for punching thin washers from e.g. aluminium foil and transferring them to a machine element 17 comprises a punch 2 provided with a concentrically arranged transfer element 10 which is axially displaceable in relation to the punch and is arranged so that immediately after the punching of a washer it transports the same further to the machine element situated at the back of a die 3. A vacuum is applied to both the elements 10, 17 in order to maintain the washer in the correct position. The arrangement is particularly suitable for the punching of thin foil washers to be applied inside bottle caps. <IMAGE>

Description

SPECIFICATION A washer-punching and transfer device The present invention relates to a unit for the punching of washers from an intermittently moving material web by means of a punch and a die and for the transfer of the punched washers to an application element situated at the back of the die.

Washers or so-called wafers of thin, plasticcoated aluminium foil are often applied inside flask and bottle caps. The washers which are punched from material in sheet or web form are very difficult to handle mechanically, owing to their smallness and low mass. It has proved impossible, for example, from a container holding a large number of readypunched washers to pick up mechanically one washer at a time in order to transfer and apply it to a cap. The handling can be made easier, however, if after the punching each washer is handled individually and transferred directly to the device by means of which the washer is applied to the cap.

By this solution the difficulty attached to the said picking up of one washer at a time from a cushioning store can be overcome, but it has remained difficult to transfer the punchedout washer from the punching unit to the application device whilst maintaining the washers in the correct position in relation both the the elements which transfer the washer and to the elements which apply them to the cap.

It is an object of the present invention to provide a punching and transfer unit by means of which a washer can be punched out and transferred directly in a simple and reliable manner to an application device situated at the back of the die.

This object has been achieved in accordance with the invention in that a unit for the punching of washers from an intermittently moving material web by means of a punch and a die, and for transfer of the punched washers to an application element situated at the back of the die has been given the characteristic that the unit comprises a transfer element which is arranged concentrically in the punch and can perform a reciprocating move ment in relation to the same.

A preferred embodiment of the unit in accordance with the invention has been given the further characteristic that the length of stroke of the transfer element is appreciably greater than the length of stroke of the punch.

This makes it possible for the punched washer to be moved to the back of the die with the help of the transfer element without the length of stroke of the punching element having to be increased.

A further embodiment of the unit in accordance with the invention has been given the further characteristic that the transfer element is movable by means of driving elements so as to come to rest against the application element, which ensures that the punched out washer is transferred in a correct position to the application element.

A further embodiment of the unit in accor dance with the invention has been given the further characteristic that the transfer element comprises ducts which end up at the end or working surface of the transfer element and can be connected to a vacuum source. The vacuum ducts make it possible to retain the punched washer in a reliable manner in con tact against the working surface of the trans fer element.

A further embodiment of the unit in accor dance with the invention has been given the further characteristic that the working surface of the transfer element is situated on a sepa rate part which is supported so that it is axially displaceable in the front end of the transfer element and is connected to it by means of a compression spring. By making the front part of the transfer element resilient, the working stroke of the transfer element can be made so long that the working surface of the transfer element is maintained for a short period in contact against the working surface of the application element, which facilitates the transfer of the washer.

A preferred embodiment of the unit in ac cordance with the invention will now be de scribed in detail with special reference to the enclosed schematic drawing, which only shows the details required for the understand ing of the invention.

The drawing shows in perspective and partly in section a unit in accordance with the invention, the main components of which are supported movably in a housing 1, which is fixed to a machine stand not shown in the drawing. The unit comprises a cylindrical punch 2 and a die 3 co-operating with the same. The punch 2 is supported so as to be axially displaceable in the housing 1 and it is adapted so that it can perform a reciprocating movement by means of a driving element 4.

The punch 2 projects slightly with its front end into the die 3 when it is in its one end position.

The punch 2 is surrounded by a substan tially annular fixing device 5 which is also supported so that it can be axially displaced in the housing 1. The fixing device 5 is provided with an annular working surface 6 extending around the front end of the punch 2, which is facing towards the die 3 and is adapted so that it is pressed against the same with the help of a compression spring 7, which is situated between the rear end of the fixing device 5 and the housing 1. The fixing device 5 has on its surface facing towards the punch 2 a number of grooves 8 which extend in the longitudinal direction of the fixing device 5 and are adapted so as to accommodate drivers 9 extending from the outer cylindrical surface of the punch 2. The grooves 8 are of such a length than the punch 2 can move freely during the greater part of its stroke.During the last part of the return stroke, however, the drivers 9 will come to rest against the rear end of the grooves 8, so that the fixing device 5 is moved in the direction away from the die against the effect of the compression springs 7, which will be described in greater detail in the following.

The punch 2 is tubular and consequently possesses a continuous cavity wherein a cylindrical transfer element 10 is supported concentrically for an axial reciprocating movement in relation to the punch 2.

The transfer element 10 is pivoted with its rear end on a driving element 11 and has at its opposite end a front part 12 which is supported so as to be axially diplaceable in the transfer element and is connected to the same via a compression spring 13. The transfer element 10 moreover comprises a centrally situated duct 14 which can be connected at the end rear of the transfer element via a flexible tube 15 to a vacuum source, not shown in the drawing. The vacuum duct 14 extends via a space accommodating the compression spring 13 into the front part 12 where the duct divides into a number of minor ducts whose openings are situated in the plane working surface 16 of the front part 12 facing towards the die 3.

On the side remote from the punch 2 or rear-side of the die 3 an application element 17 is situated which is movable between at least one position axially in line with the transfer element 10 and one position wherein the application element is axially in line with a cap to which a punched material washer is to be transferred. The application element 17 is substantially cylindrical with a plane front working surface which is adapted so as to cooperate with the working surface 16 of the transfer element 10. The application element 17, like the transfer element, has a substantially centrally situated duct 18 which can be connected to a vacuum source. The duct 18 divides at the front end of the application element into a number of ducts which end up in the working surface of the element.

As can be seen from the drawing an interspace or gap exists between the die 3 and the movable parts of the unit when these, that is to say, the punch 2, the fixing device 5 and the transfer element 10, are in their rear position shown in the drawing. In the said gap moves a material web 20, guided with the help of guide rollers 19 (only one of which is visible in the drawing) in such a manner that it passes straight before the punch 2 and the edge of the die 3 cooperating with the punch.

When washers or wafers are to be punched out of the material web 20 with the help of the unit according to the invention, the material web is first introduced into the gap shown in the figure between the die and the movable parts of the unit. The material web runs over guide rollers which guide the web so that it passes centrally straight before the punch 2.

The material web 20 is advanced during operation stepwise or intermittently, each advance moving the material web over a length which exceeds a little the diameter of the punchedout washer. Consequently, the waste material will remain in the form of a web, which facilitates the advancing of the web as well as the taking care of and recovery of the waste material.

After the introduction of the material web into the unit and the putting into operation of the stepwise advance of the web, the driving of the movable parts of the unit is started so that the same describe repeated reciprocating movements which are synchronized with the stepwise advance of the web. In the intention of simplifying the description and making the invention more readily understandable, only one working cycle will be described in the following, athough in practical operation the unit performs a large number of connecting working cycles with continued stepwise feeding of the material web.

The tubular punch 2 is driven at the start of a working cycle with the help of the driving element 4 from the rear reversal position shown in the direction of the die 3. The fixing device 5 situated around the punch 2 will follow the movement of the punch 2, since it is urged by the compression springs 7 to be constantly in contact with the drivers 9 of the punch 2. When the punch 2 has been moved over approxiamtely half its stroke length in the direction towards the die 3, the advance of the material web 20 is stopped, and directly after this the front working surfacer6 of the fixing device 5 will come to rest against the material web so that the latter is fixed by the force of the compression springs 7 between the fixing device and the die 3. On continued movement of the punch 2 towards the right in the figure the drivers 9 will be moved freely forwards in the grooves 8 in the fixing device, which consequently remains in the said position fixing the material web 20 during the remaining part of the working stroke of the punch 2. During the earlier part of the working stroke of the punch 2, the working stroke of the transfer element 10 driven by the driving element 11 has also started. The transfer element is moved at a higher speed than the punch 2 which has the result that the working surface 16 on the front part 12 of the transfer element 10 is substantially at equal height with the front working surface of the punch 2 when the same has passed the edge of the die 3 and has punched out a material washer from the material web 20.

The punch 2 has attained its front reversal position directly after the punching out of the washer and therefore commences its return stroke, whilst the transfer element 10 continues its movement in the direction towards the application element 17. With the help of the vacuum in the duct 14 the punched-out washer will now be retained in correct, centred position on the working surface 16 of the front part 12 and be moved through the die 3 to rest against the front working surface of the application element 17. At the same time as the material washer comes into contact with the application element 17 the connection of the duct 14 with the vacuum source (not shown) is broken and the duct is connected instead to atmosphere.At the same time the duct 18 in the application element 17 is connected to a vacuum source, and the punched-out washer thus will be moved to and retained on the application element 17 when the transfer element 10 commences its return stroke. The transfer element 10 in its front reversal position is so situated that the front part 12 of the transfer element, with the help of the compression spring 13, will be retained in contact with the application element during the last part of the working stroke as well as the first part of the return stroke, which ensures that even at a high working speed the working surface 16 of the transfer element will be pressed against the working surface of the application element 17 for such a length of time that the changeover of the connection of the two ducts 14 and 18 to the vacuum source and atmosphere respectively can take place without difficulty.The transfer element 10 performs a relatively fast return movement back to the position shown in the figure, which it attains substantially at the same time as the punch 2 and the fixing device 5 which is moved back by the drivers 9 of the punch. At the same time the application element 17 is moved to a position in which the punched-out material washer can be transferred to a cap and a new application element assumes the position as shown, axially in line with the transfer element 10. After renewed stepwise advance of the material web 20, the process is repeated.

Since the stresses on the transfer element 10 are appreciably smaller than the stresses on the punch 2, the transfer element can be made considerably slighter and of a lower mass than the punch 2. As a result the transfer element, whose length of stroke is appreciably greater than the length of stroke of the punch, can work at a higher speed without any vibrations or other difficulties being experienced. Since the punch 2 does not participate in any manner in the transfer of the punched washer to the application element 17, its length of stroke can be kept short and its speed relatively low, which is an advantage in punching work, not least from a point of view of wear.Since the application element 17, after it has rotated to a position axially in line with a cap (not shown) must be in a correct position in respect to the cap, it is a great advantage that the application element is of a non-resilient type. This is made possible because the flexibility required for the transfer of the punched washer is acchieved with he help of the spring-loaded front part 12 of the transfer element 10. The compression spring 13 is given a rigidity which is such that the pressing in of the front part 12 against the effect of the spring force is initiated only when the working surface 16 comes to rest against the application element. This ensures that the washer is not displaced from its position during the transfer.

The unit in accordance with the invention has proved to operate well and to make possible in spite of a high rate of operation an accurate punching out of the washers and a reliable transfer of the washers to a correct position on the application device.

Claims (7)

1. A unit for the punching of washers from an intermittently moving material web (20) by means of a punch (2) and a die (3) and for the transfer of the punched washers to an application element (17) situated at the back of the die (3), characterized in that the unit comprises a transfer element (10) which is arranged concentrically in the punch (2) and can perform a reciprocating movement in relation to the same.

2. A unit in accordance with Claim 1, characterized in that the length of stroke of the transfer element (10) is appreciably greater than the length of stroke of the punch (2).

3. A unit in accordance with Claim 1 or 2, characterized in that the transfer element (10) is movable by means of driving element (11) so as to come to rest against the application element (1 7).

4. A unit in accordance with any one of the preceding claims, characterized in that the transfer element (10) comprises ducts (14) which end up at the end or working surface (16) of the transfer element and can be connected to a vacuum source.

5. A unit in accordance with any one of the preceding claims, characterized in that the working surface (16) of the transfer element (10) is situated on a separate part (12) which is supported so that it is axially movable in the front end of the transfer element (10) and is connected to it by means of a compression spring (1 3).

6. A washer-producing device comprising punch means for punching a washer from sheet material and a transfer member adapted to receive the punched washer and move it to a succeeding position in the course of final fitment.

7. A washer-producing device substan tially as described herein with reference to the accompanying drawings.