WO2009035316A1

WO2009035316A1 - Device for cotton discs as well as method for manufacturing thereof

Info

Publication number: WO2009035316A1
Application number: PCT/NL2007/000223
Authority: WO
Inventors: Pieter Cornelis Meijers; Gerardus Johannes Catharina Van Laar; Gert De Gooyer
Original assignee: Ebm Techniek B.V.
Priority date: 2007-09-12
Filing date: 2007-09-12
Publication date: 2009-03-19

Abstract

The invention relates to a method for manufacturing cotton pads, the method comprising the steps of : a) supplying a web of basic material (10) for the cotton pads; b) placing the basic material between a row of lower and upper dies (4, 5) displaceable toward each other; c) punching a row of cotton pads of the same form out of the web by displacing the lower and upper dies toward each other; d) displacing the web transversely of the supply direction and in the supply direction; and e) repeating steps c) and d) such- that the rows of cotton pads are punched out in mutually offset position.

Description

DEVICE FOR COTTON DISCS AS WELL AS METHOD FOR MANUFACTURING THEREOF

The invention relates firstly to a method for manufacturing cotton pads . Cotton pads are manufactured from a web of basic material which can consist for instance of a single layer or a number of layers, such as two non-woven outer layers and a cotton fibre layer therebetween. Cotton pads are formed from such a web of basic material by punching discs out of this web by means of dies. It is usual in the prior art to provide two die blocks in which there are a number of rows of upper dies and a number of rows of lower dies. One block is arranged in stationary manner in the machine, while the other block is movable up and downward by means of for instance a crankshaft. When such a machine must now be changed over for another type of cotton pad, for instance of a different diameter or of different shape, both die blocks must then be replaced. This is because the diameter of the lower and upper dies must be modified as well as the mutual distance between the different dies. This is a relatively costly operation.

In addition, the up and downward movement of such a die block involves great forces as a result of the weight of such a die block.

It is now an object of the invention to provide a method which alleviates or even obviates the above stated drawbacks . This objective is achieved according to the invention with a method for manufacturing cotton pads, the method comprising the steps of: a) supplying a web of basic material for the cotton pads; b) placing the basic material between a row of lower and upper dies displaceable toward each other; c) punching a row of cotton pads of the same form out of the web by displacing the lower and upper dies toward each other; d) displacing the web transversely of the supply direction and in the supply direction; and e) repeating steps c) and d) such that the rows of cotton pads are punched out in mutually offset position.

By providing only a single row of dies, and herein displacing the web of basic material transversely of the supply direction and in the supply direction, it is possible to punch cotton pads out of the basic material with this single row of dies such that the rows of punched-out cotton pads are offset relative to each other. The use of a single row of dies moreover provides the advantage that the die block is reduced considerably in weight, and the replacement of such a row of dies is moreover a less costly affair. Only after replacement of the row of dies by a row of dies of other dimensions is it important to adjust the displacement in supply direction and transversely thereof to these dimensions, so that the basic material is used optimally for punching of pads therefrom.

In a preferred embodiment of the method the repeated displacement of the web transversely of the supply direction and in the supply direction results in a zigzag displacement of the web. The advantage hereof is that the reciprocal movement of the web is minimal relative to a central axis, wherein the advantage of the invention is nevertheless obtained. The invention further comprises a device for manufacturing cotton pads, which device comprises:

- a row of lower and upper dies displaceable toward each other; - a supply roll with basic material for the cotton pads ; and

- a basic material guide arranged in front of and a basic material guide arranged behind the row of dies.

Such a device is per se known from the prior art. In order to achieve the stated objective, a device according to the invention is characterized in that both the basic material guides can be displaced together transversely of the supply direction. Because the guides are displaceable transversely of the supply direction, a zigzag movement of the basic material can be realized in combination with a displacement of the basic material in the supply direction such that rows of cotton pads can be punched out of the basic material in mutually offset position.

In the preferred embodiment of the device according to the invention the lower and upper dies can be exchanged. This enables a rapid changeover of the device according to the invention, and the device can hereby be changed over rapidly to a cotton pad machine for a different type of cotton pad. In combination with modifications to the displacement transversely of the supply direction and in the supply direction itself, the device can be changed over in a short time.

In another embodiment the dies are rotatable around an axis perpendicularly of the plane of the basic material situated between the dies. The punching pattern of the dies can hereby be adapted, whereby a nested pattern is for instance obtained. The transverse displacement can hereby In another embodiment of the device according to the invention at least one of the lower and upper dies are provided with chambers which are arranged behind the dies and which are in fluid communication with each other and filled with a hydraulic means in order to equalize height differences between the dies. It is usual to arrange a plastic ring under the dies which provides a suspension, whereby minimal height differences between the dies are compensated. Such a plastic ring has the drawback that the correction time in which the plastic ring takes on its original dimensions can be too long at higher speeds of a cotton pad machine. By now providing chambers in which hydraulic fluid is arranged, the height difference between the different dies is equalized and a suspension is no longer necessary. A buffer vessel can optionally be incorporated in the hydraulic circuit which ensures that the whole row of dies can spring back in the unlikely event something enters between the dies, which could cause damage to the dies.

In a preferred embodiment of the device according to the invention the basic material guides each comprise two nip-forming rollers between which the basic material is carried. By carrying the material between two rollers which compress the basic material, it is possible to bring about a rapid displacement of the basic material in transverse direction. Because the rollers are arranged on either side of the rows of dies and because the rollers compress the basic material, the material can be displaced between the dies rapidly and accurately in zigzag direction. The rollers, which each form a nip in axial direction, are herein moved reciprocally.

In a prior art cotton pad machine it is usual to press the punched-out cotton pads through the upper die into cotton pads . Stacks of cotton pads are hereby formed in the housing. In order to now remove such a stack from the housing for further processing, it is usual to stop the machine so that there is sufficient time to take the stack of cotton pads out of the housing using grippers . Stopping the machine, particularly in the case of large and heavy die blocks, has the drawback that a great deal of energy is consumed in stopping and restarting the machine. Some of this energy can be stored in a flywheel which can give back part of the energy via a coupling.

It is now an object of the invention to enable the removal of a stack of cotton pads without having to stop the cotton pad machine.

This objective is achieved according to the invention with a device for stacking cotton pads, the device comprising:

- an elongate tubular housing with a cross-section adapted to the form of the cotton pads, wherein the housing is open on both top and bottom side and is provided in lengthwise direction with a channel;

- an internal first rib arranged in the housing on the infeed side;

- an internal second rib arranged at a distance from the first rib; - at least one displaceable removing finger which protrudes at least partially into the housing in lengthwise direction via the channel and has a starting position between the first and second rib.

By arranging two ribs at a distance from each other it is possible, while cotton pads are being pressed into the housing, to create a distance between which a removing finger can be inserted in order to lift a stack of cotton pads out 2007/000223

cotton pads are thus normally pressed to a position past the first rib so that a stack of cotton pads is formed on top of the first rib. When this stack is taken out, the cotton pads are temporarily pressed as far as the lower second rib, so that a distance is created between the last introduced cotton pads and the already formed stack of cotton pads. This distance makes it possible to insert a removing finger and take out a stack of cotton pads . The small stack of cotton pads formed on the second rib can then be pressed through to a position above the first rib and there supplemented to form a full stack of cotton pads. Two removing fingers are preferably arranged on either side of the housing, which guarantees a stable removal of the stack of cotton pads.

The invention further comprises a method for stacking cotton pads and removing a stack of cotton pads, the method comprising the steps of: a) pressing a punched-out cotton pad repeatedly out of a die to a first level in a housing in order to form a stack of cotton pads in the housing; b) starting a removal operation which comprises the steps of:

* pressing punched-out cotton pads temporarily to a second lower-lying level in the housing;

* inserting removing means between the first and second level and lifting the stack of cotton pads out of the housing; c) repeating steps a) and b) , wherein the cotton pads at the second level are pressed through to the first level.

In a conventional cotton pad machine the means which presses a cotton pad out of a die into the housing is arranged on a drive rod which is in turn mounted on the crankshaft with which one of the die blocks is also moved up to that of the die block enables pressing-out to take place once the dies have punched the cotton pad. In conventional machines it is further per se known to make the drive rod adjustable in length so that various aspects can be adapted to the relevant dimensions of the cotton pads and the housings used to stack the cotton pads. This length adjustment could optionally be used to press the cotton pads as desired to the first or the second rib in the housing. It is however an object of the invention to provide an elegant and simple solution which is as far as possible independent of speed.

This object is achieved with a device according to the invention which comprises:

- a crankshaft; - a two-part drive rod with an end bearing-mounted on the crankshaft;

- a means arranged on the other end of the drive rod for the purpose of engaging a cotton pad;

- a control rod which is arranged pivotally at one end on the pivot point of the two-part drive rod, and wherein the other end is arranged displaceably such that by displacing the other end the effective length of the two-part drive rod can be adjusted.

Because the drive rod is in two parts, the effective length of the drive rod can be adjusted by displacing the pivot point between the two parts of the two-part drive rod. The length of the drive rod can be adjusted within a very short time simply by displacing the control rod arranged on the pivot point of the two-part drive rod. The other end of the control rod is preferably arranged along the periphery of a rotatable disc. This disc can then be driven by means of a servomotor so that a very 00223

cotton pads as desired to the first or second rib in the housing .

These and other features of the invention are further elucidated with reference to the accompanying drawings. Figure 1 shows a perspective view of a cotton pad machine with improvements according to the invention.

Figures 2 and 3 show schematically an embodiment of the method for manufacturing cotton pads according to the invention. Figure 4 is a diagram showing the timing of the dies and the ejectors.

Figures 5-10 show different positions of the dies and the ejectors in accordance with the diagram of figure 4.

Figure 11 shows a side view of an embodiment of a device for pressing cotton pads according to the invention as desired to a first level or a second level in a housing.

Figure 12 shows a cross-sectional view of the removing fingers for taking a stack of cotton pads out of a housing. Figure 13 shows a cross-sectional view of the hydraulic chambers under a row of dies.

Figure 14 shows a cross-sectional view of the crankshaft having thereon the drive rod for the row of lower dies and the drive rods for the ejectors. Figure 15 shows schematically an alternative of the invention.

Figure 1 shows a perspective view of a cotton pad machine 1. This cotton pad machine 1 has a baseplate 2 with a frame 3 thereon. A row of upper dies 4 is arranged fixedly in frame 3. The row of lower dies 5 is placed on a yoke 6 which moves up and downward via guides 7. This yoke 6 is moved up and downward by means of a drive rod 8 arranged on a crankshaft 9. A web of basic material 10 is guided between the row of upper dies 4 and the row of lower dies 5.

Further provided in the frame is a row of ejectors 11 which can protrude through the row of lower dies 5 in order to thus press punched-out cotton pads into housing 12. The row of ejectors 11 is driven by a two-part drive rod 13, likewise arranged on crankshaft 9.

Figures 2 and 3 show schematically the movement of the web of basic material 10. The row of upper dies 4 and lower dies 5 is shown schematically and the punched-out cotton pads 14 have dark hatching. Once a row of cotton pads 14 has been punched out, the web of basic material 10 must then be displaced in the supply direction through a distance y and also transversely of this supply direction through a distance x. This ensures that one row of cotton pads 14 at a time is punched out, and that furthermore the basic material 10 is optimally utilized. The distances x and y depend on the form and dimensions of cotton pads 14.

Figure 4 shows a graph with the timing of the movement of lower dies 5 and ejectors 11. The line 15 shows the movement of lower dies 5, while line 16 shows the movement of ejectors 11. The different positions are shown in cross-section in the following figures.

Figure 5 shows the position at 0 degrees according to figure 4. The lower row of dies 5 is situated at 0 degrees in the lowermost position, while ejectors 11 moved downward. The web of basic material 10 is held fast on either side of dies 4,5 between nip-forming rollers 17,18.

Figure 6 shows the position wherein ejectors 11 have just passed through the lowest point and are moving upward again while lower die 5 is just coming into contact with web 10. Lower die 5 then moves (see figure 7) into the uppermost position in which, in combination with upper die 4, a cotton pad 14 is punched out. The ejectors have herein moved further upward and are already located partially in lower dies 5.

As shown in figure 8, ejectors 11 then press cotton pad 14 into housing 12 while lower dies 5 are already moving downward again.

Once the punched-out cotton pads 14 have been carried into housing 12, ejector 11 also moves downward again so that the ejector moves below web 10. At that moment the nip- forming rollers 17 can be driven so that the web of basic material 10 is displaced in the supply direction as well as transversely thereof. The row of lower dies 5 has meanwhile almost reached its lowest point, while ejectors 11 move still further downward. The cycle can then be repeated again.

Figure 11 shows the mechanism for ejectors 11 in further detail. Ejectors 11 are driven by a two-part drive rod 13. This two-part drive rod 13 is arranged on crankshaft 9. Two-part drive rod 13 consists of a lower part 19 and an upper part 20 which are connected to each other via a pivot point 21. Further connected to this pivot point 21 is a control rod 22 which at an end 23 is arranged fixedly on a disc 24. In the position shown in full lines the control rod 22 has pulled pivot point 21 out of centre, whereby the stroke of two-part drive rod 13 is shortened. By rotating disc 24 to the position indicated with broken lines the two- part drive rod 13 can be placed in the position where it can make a maximum stroke. The shown position with shortened stroke is important for removal of a stack of cotton pads 14 formed in housing 12.

Figure 12 further shows the removal of a stack of of ejectors 11 the cotton pads 14 are now pressed to a lower- lying rib 25 in housing 12. This creates a space 26 between the stack of cotton pads 14 lying on an upper rib in housing 12 and the cotton pads which, due to the shortened stroke, are pressed only as far as lower rib 25. Due to the creation of this space 26 two removing fingers 27 can be placed under stack 14, after which stack 14 can be taken out of housing 12 via channels in the wall. As soon as fingers 27 remove stack 14, the stroke of ejectors 11 can once again be lengthened so that cotton pads 14 are pressed as far as the upper rib in housing 12. It hereby becomes possible to remove stacks of cotton pads without stopping the cotton pad machine 1.

Figure 13 shows a cross-section of lower dies 5 in more detail. Lower dies 5 are arranged slidably in yoke 6 and are supported by bushes 28. Together with yoke 6, these bushes 28 form chambers 29 which are in fluid communication with each other. These chambers 29 are filled with a hydraulic fluid or hardly compressible fluid, whereby height differences between the different lower dies 5 can easily be equalized as soon as lower dies 5 come into contact with upper dies 4.

Figure 14 shows a cross-sectional view of crankshaft 9 on which drive rod 8 is bearing-mounted as well as the lower part 19 of two-part drive rod 13. Further provided on crankshaft 9 is a flywheel 30 which equalizes variations in load as a result of the punching.

The crankshaft is mounted via bearings 31 and 32 which are each accommodated in a bearing housing 33 and 34 respectively in frame 3. By giving these bearing housings 33, 34 a slightly eccentric form it is possible to enable a fine adjustment of drive rod 8. This is because it is essential that lower dies 5 and upper dies 4 come into mutual contact A high precision is required here. Such an adjustment is possible by making bearing housings 33,34 eccentric, while drive rod 8 can be manufactured integrally.

Figure 15 shows schematically an alternative of the invention. A web of basic material 10 is here also shown and a row of upper dies 4 and lower dies 5 are shown schematically. The cotton pads 14 shown with hatching are punched out per punching movement. Because dies 4, 5 are rotated relative to the transport direction 40 of basic material 10, a nested pattern can be obtained while basic material 10 is transported in a straight line. It is also possible to make a combination of the embodiment according to figures 2, 3 and figure 15, wherein only a small transverse displacement is necessary and upper and lower dies 4, 5 are also rotated.

Claims

1. Method for manufacturing cotton pads, the method comprising the steps of: a) supplying a web of basic material for the cotton pads ; b) placing the basic material between a row of lower and upper dies displaceable toward each other; c) punching a row of cotton pads of the same form out of the web by displacing the lower and upper dies toward each other; d) displacing the web transversely of the supply direction and in the supply direction; and e) repeating steps c) and d) such that the rows of cotton pads are punched out in mutually offset position.

2. Method as claimed in claim 1, wherein the repeated displacement of the web transversely of the supply direction and in the supply direction results in a zigzag displacement of the web.

3. Device for manufacturing cotton pads, which device comprises : - a row of lower and upper dies displaceable toward each other;

- a supply roll with basic material for the cotton pads;

- a basic material guide arranged in front of and a basic material guide arranged behind the row of dies; characterized in that both the basic material guides can be displaced 7 000223

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4. Device as claimed in claim 3, wherein the lower and upper dies can be exchanged.

5. Device as claimed in claim 3 or 4, wherein at least one of the lower and upper dies are provided with chambers which are arranged behind the dies and which are in fluid communication with each other and filled with a hydraulic means in order to equalize height differences between the dies.

6. Device as claimed in any of the claims 3-5, wherein the basic material guides each comprise two nip- forming rollers between which the basic material is carried.

7. Device as claimed in claim 6, wherein the two rollers of a basic material guide are displaceable- in axial direction.

8. Device as claimed in any of the claims 3-7, wherein the dies are rotatable around an axis perpendicularly of the plane of the basic material situated between the dies.

9. .Device for stacking cotton pads, the device comprising: - an elongate tubular housing with a cross-section adapted to the form of the cotton pads, wherein the housing is open on both top and bottom side and is provided in lengthwise direction with a channel;

- an internal first rib arranged in the housing on the infeed side;

- an internal second rib arranged at a distance from the first rib;

- at least one displaceable removing finger which protrudes at least partially into the housing in lengthwise direction via the channel and has a starting position between the first and second rib.

10. Device as claimed in claim 9, comprising two 23

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11. Method for stacking cotton pads and removing a stack of cotton pads, the method comprising the steps of: a) pressing a punched-out cotton pad repeatedly out of a die to a first level in a housing in order to form a stack of cotton pads in the housing; b) starting a removal operation which comprises the steps of:

* pressing punched-out cotton pads temporarily to a second lower-lying level in the housing; * inserting removing means between the first and second level and lifting the stack of cotton pads out of the housing; c) repeating steps a) and b) , wherein the cotton pads at the second level are pressed through to the first level.

12. Device for pressing cotton pads as desired to a first level or a second level in a housing, which device comprises :

- a crankshaft;

- a two-part drive rod with an end bearing-mounted on the crankshaft;

13. Device as claimed in claim 12, wherein the other end of the control rod is arranged along the periphery of a rotatable disc.

14. Device as claimed in claim 12 or 13, wherein the crankshaft is bearing-mounted in rotatable eccentric discs in