GB2092055A

GB2092055A - Method of manufacturing corrugated sheets continuously and an apparatus for carrying out the method

Info

Publication number: GB2092055A
Application number: GB8133892A
Authority: GB
Original assignee: TAKIRON UK Ltd
Current assignee: TAKIRON UK Ltd
Priority date: 1980-12-29
Filing date: 1981-11-10
Publication date: 1982-08-11
Also published as: JPH0140744B2; JPS57125007A; GB2092055B

Abstract

Method and apparatus for continuous manufacture of corrugated sheets P of thermoplastic synthetic resin the apparatus including an extruder 11 to produce sheeting, a polishing station 12, a corrugating station 13, a trimming station 14, a takeup station 15 and a cutting station 17, the corrugating station 13 having at least two sets of pairs of corrugating rolls A and B of different types in each set whereby corrugation of different types can be applied to the sheeting respectively, and the sets of rolls A and B being movable in this case vertically to move the required set of rolls into position to corrugate the sheeting.

Description

SPECIFICATION Method of manufacturing corrugated sheets continuously, and an apparatus for carrying out the method This invention relates to a method of manufacturing a corrugated synthetic resin sheeting continuously, and an apparatus for carrying out the method. More particularly, it is concerned with a method of, and apparatus for the continuous manufacture of a corrugated sheeting which permit changing of the corrugated pattern on the corrugated product without interrupting the moulding operation.

It is known to manufacture corrugated synthetic resin sheets having a single corrugated pattern applied continuously on a mass-production basis by employing a large moulding line which handles all the steps including extrusion moulding of synthetic resin sheeting, polishing, corrugation, trimming, cutting and delivery at stations arranged in line.

In the event that it is required to apply a different corrugated pattern, however, it is necessary to change all the equipment handling the sheeting which has left the extruder and the polishing station, i.e., a series of equipment from the corrugating apparatus to the discharge station. Although a series of equipment from the corrugating apparatus to the discharge station is usually carried on a single support of bogie, the change of such equipment involves a down time of at least four hours, which is a heavy loss of time, as well as of labour.

The extensive change of equipment has been unavoidable for the manufacture of corrugated sheets having different corrugated patterns in a single production line. This is due to the serial combination of the extruder and the corrugating apparatus which has a lot of disadvantage as will hereunder be summa rized: 1) PVC, which is a thermoplastic synthetic resin most usually employed for the manufacture of corrugated sheets, is liable to thermal decomposition. If the extruding operation is interrupted, the PVC remaining in the extruder and the die is decomposed, and corrodes the extruder and the die. The work of dismantling the extruder, grinding the corroded parts, and reassembling it brings about a heavy loss of time amounting to at least 20 hours.

2) If the work of changing the corrugating apparatus and the like is performed with the extruder kept in operation in order to avoid the loss of time referred to in 1) above, there results a loss of the synthetic resin until the change of equipment is finished. This loss amounts to at least 680 kg if the extruder extrudes the resin at a rate of 170 kg per hour.

3) In order to avoid the loss of the synthetic resin pointed out in 2) above, it may be possible to cool any synthetic resin sheeting extruded from the extruder during any such change of equipment, and crush it into pellets for reuse. This work of regeneration, however, requires a considerable amount of labour, and a separate series of equipment 4) Large spaces are required for preparing and storing different corrugated apparatus for corrugating sheets in different patterns, and any other apparatus associated therewith, and for changing the apparatus.

5) A series of equipment which has to be changed is usually held together by a frame, and defines a very large integrated assembly which is not easy to move.

In the manufacture of corrugated synthetic resin sheets it has been usual to try to lower the costs of the products by manufacturing only limited kinds of products each in a large quantity. Recently, however, the demand has been diversified, and it is necessary to manufacture many kinds of products in small quantities. This demand is yet to be satisfied on an industrial basis because of the various problems involved in the change of equipment.

The object of this invenion is to provide a method of manufacturing corrugated sheets of a thermoplastic synthetic resin, having different corrugated patterns, continuously without interrupting the extruding operation, which eliminates the various drawbacks of the prior art.

In accordance with a first aspect of the invention there is provided a method of manufacture corrugated sheets of a thermoplastic synthetic resin, continuously, comprising passing continuously extrusion moulded thermoplastic synthetic resin sheeting between pairs of upper and lower corrugated rolls under heat in a corrugating station said station having said pairs of corrugated rolls in a plane in which said sheeting is fed, the corrugating station further including other pairs of upper and lower corrugated rolls, said pairs of corrugated rolls and said other pairs of corrugated rolls being interchangeable with each other in said plane without interrupting the extrusion moulding of said sheeting.

It is also an object of this invention to provide apparatus for carrying out the method of manufacturing corrugated sheets of a theremoplastic synthetic resin, having different corrugated patterns, continuously, allowing easy change of the corrugated patterns without interrupting the work of extrusion moulding the synthetic resin sheeting.

According to a further aspect of the invention there is provided apparatus for the continuous manufacture of corrugated sheets of a thermoplastic synthetic resin including a synthetic resin sheeting extruder, a polishing and preheating station, a corrugated station a trimming station, a takeup station, and a cutting station, said corrugating station comprising at least two spaced rows of pairs of corrugated rolls having different corrugated patterns, and means for vertically moving the upper or lower row of pairs of corrugated rolls into a plane in which synthetic resin sheeting is fed.

Preferably the take up station comprises a large diameter roll bearing in use against the lower surface of corrugated sheeting, a first pressing roll disposed above said corrugated sheeting, and having a corrugated pattern corresponding to the corrugated pattern on said corrugated sheeting, and a second pressing roll having a different corrugated pattern, and which is interchangeable with said first pressing roll.

By these means it is possible to manufacture corrugated sheets continuously in differently corrugated patterns having, for example, small corrugations having a pitch of about 30 to 70 mm, large corrugations having a pitch of about 70 to 130 mm, or square corrugations, by a single series of equipment.

The invention will now be described by way of example with reference to the drawings in which: Figure 1 shows diagrammatically conventional apparatus for the manufacture of corrugated sheets of thermoplastic synthetic resin, Figure 2 shows diagrammatically. apparatus for the manufacture of corrugated sheets, in accordance with the invention, Figure 3A shows rolls used in the apparatus, Figure 3B shows further rolls used in the apparatus, and Figure 4 is a perspective view of part of the apparatus of Fig. 2, showing the corrugating roll unit.

Fig. 1 shows apparatus of the kind commonly used and having a series of stations including an extruding station 1, for moulding synthetic resin material. The extruder has a shaped or circular sheet moulding die by which a thermoplastic synthetic resin, for example polyvinyl chloride (PVC), is extrusion moulded into sheeting having a thickness of 0.6 to 1.0 mm. The sheeting is passed to a polishing station including rolls 2 around which the sheet passes. It then enters a corrugating station 3. The corrugating station 3 has a corrugating apparatus which comprises a plurality of pairs of corrugated rolls each pair being for example of the kind illustrated in Figs. 3A or 3B. The sheeting thus corrugated is cold and solid when leaving the corrugating station.The corrugated sheeting is trimmed along its longitudinal edges by a trimming device 4, and passes to take up rolls 5 and then cut by a cutter 7 into sheets P of predetermined unit length, while being held by a vice 6 travelling synchronously with the corrugated sheeting. The corrugated sheets P are separated from the line by a discharge roll device 8 and delivered to a storage area.

Fig. 2 shows apparatus as constructed according to this invention. In this example sheeting of a thermoplastic synthetic resin, such as a polyvinyl chloride or polycarbonate resin, having a thickness of 0.6 to 1.0 mm is extruded through a die in an extruder 11 at a rate of 3.0 to 3.5 meters per minute. The sheeting is passed round polishing rolls 12, and preheated to a temperature of 1 20 C to 1 30to by a preheating unit 12'. The preheated sheeting is fed into a corrugating roll unit 13.

The corrugating roll unit 13 is shown in detail in Fig. 4. This has upper and lower pairs of corrugated rolls A and B the upper pairs of corrugated rolls A and the lower pairs of corrugated rolls B being disposed in vertically spaced apart relationship in a vertically movable frame 33. Eight double stage takeup units 36 are provided upright on each side of the vertically movable frame 33. Eight pairs of upper and lower corrugated rolls A are provided in the lower portions of the takeup units 36, while eight pairs of upper and lower corrugated rolls B are provided in the upper portions of the takeup units 36. Mechanisms 32 for raising and lowering the frame 33 are positioned at the four corners of the frame 33, and carried on a support or bogie 31 adapted to move on rails 1 0 (shown in Fig.

2). The mechanisms 32 support the vertically movable frame 33, and are for moving it vertically. The mechanisms 32 may comprise mechanical means such as gears, or hydraulic or pneumatic means. A pipeline 34 or 34' is connected to each corrugated roll by a rotary joint to supply a heating medium, such as hot water, to the roll to control its temperature.

Slidable reinforcing frames 35 are provided for preventing the frame 33 from swaying.

The sheeting, which is preheated to a perdetermined temperature, and fed to the corrugated roll unit 13, is corrugated when passing between the pairs of upper and lower corrugated rolls A having a corrugated pattern as shown, by way of example, in Fig. 3A. The temperature of the rolls is so controlled that it may gradually become lower from the inlet to outlet of the corrugated roll unit 13. Accordingly, the corrugated sheeting is cold and solid when leaving the roll unit 13 to enable a trimming operation to be carried out immediately at a trimming station. The corrugated sheeting is trimmed along its longitudinal edges in a trimming unit 14, to ensure a constant predetermined width. The sheeting then arrives at a take up station with take-up roll 15 running at a speed matching that of extrusion moulding.

The take up station has a roll which has a pattern matching the corrugating roll pattern on rolls A and is mounted on a reversible carrier at the other end of which is a roll of different pattern matching the corrugating rolls B. The rolls A and B of the take up station 15 are mounted on a reversible carrier pivotal about a pivot 15'. The corrugated roll in use at this station presses against a larger rubber roller C on which the sheet is supported as it passes through this station, and is thence delivered to a vice 16 and cutter unit 17. Delivery is by a delivery roll unit 18. The corrugated sheeting is guided along a path extending through the vice 16 and cutter unit 17 and a delivery roll unit 18. When the leading edge of the sheeting has abutted on a limit switch 20, the vice 16 closes to grip it.

Upon closure of the vice 16, the vice 16 and cutter unit 17 moves in the direction of travel of the sheeting at a speed which is equal to the speed of travel of the sheeting. After the vice 16 and cutter unit 17 has moved a predetermined distance, the cutter 17 cuts transversely across the sheeting. Then, the vice 16 opens, and the vice 16 and cutter unit 17 return to their original positions. The corrugated sheet products P thus obtained are rapidly delivered by the delivery roll unit 18 to a stacker for storage.

The foregoing is a description of a process for the manufacture of corrugated sheet products having a corrugated pattern of the shape produced by the rolls in Fig. 3A. If it is desired to manufacture corrugated sheets having a different corrugated pattern such as that in Fig. 3B without interrupting the extrusion moulding of the synthetic resin sheeting this is achieved by respositioning the rolls. The pairs of corrugated rolls B provided in the upper portion of the corrugated roll unit 13, and having the corrugated pattern as shown, are preheated by hot water to a predetermined temperature. The sheeting is cut between the extruder 11 and the corrugated roll unit 13. Sheeting continuously arriving from the extruder is stored until the corrugated rolls B replace the corrugated rolls A, and become ready for the corrugating operation.A motor is placed in operation for driving the roll unit 13 raising and lowering mechanisms 32 to lower the vertically movable frame 33 until the corrugated rolls B are in alignment with the extruder and polishing output. The takeup station roll at 15 is also changed from type A to type B to suit the new corrugated pattern.

The new sheeting which has been temporarily stored is inserted at its leading edge between the upper and lower corrugated rolls B, and passed through the corrugated roll unit 13, the trimming unit 14 and the takeup roll station 15. The equipment is now ready for the continuous manufacture of corrugated sheets having the corrugated pattern corresponding to rolls B, in the similar manner to corrugated sheet having the corrugated pattern or rolls A.

Only a short time of, say, three or four minutes is required for changing the corrugated rolls A to the rolls B. The sheeting stored during the change of the rolls has only a length of, say, 10 m. The sheeting is, therefore, easy to insert between the new pairs of corrugated rolls to continue the manufacture of corrugated sheets.

Although the foregoing description has referred to an embodiment in which the two different types of corrugated rolls are positioned interchangeably in a vertical plane, it is also possible to position them in a horizontal plane. It is alternatively possible to position different types of corrugated rolls in both vertical and horizontal planes so that they may be brought to their corrugating position as required. It is important to ensure that the rolls be changed quickly.

The various units 12, 13 14, 16 and 18 in the apparatus are carried on a pair of rails 10 to maintain the travel of the corrugated sheeting in a fixed direction. Alternatively, it is possible to engage the wheels only on one side of the units with a rail so that the units may be maintained in alignment with one another, while the wheels on the other side are free to travel on a flat surface, whereby the movement and arrangement of the entire apparatus can be facilitated.

Each corrugated roll of any type may comprise a plurality of unit member a as shown by broken lines in Fig. 3A. Corrugated rolls of this type are useful for the manufacture of corrugated sheets having different widths, light in weight and easy to handle, and provides a very high working efficiency in the interchange of corrugated rolls, change of rolls not in use, ect.

The apparatus is thus used to carry out a method which permits continuous manufacture of corrugated sheets of different types without interrupting the operation of the extruder, since the corrugated rolls can be changed quickly. The loss of a synthetic resin sheeting can be substantially eliminated. As it is sufficient to change only a part of the apparatus, the work of any such change is easy, and requires only a small amount of labour. After any such change, it is possible to resume the corrugating operation quickly. The corrugated rolls not in use for the corrugating operation can be changed for other types without interferring with the manufacturing process.

Claims

1. A method of manufacturing corrugated sheets of a thermoplastic synthetic resin, continuously, comprising passing continuously extrusion moulded thermoplastic synthetic resin sheeting between pairs of upper and lower corrugated rolls under heat in a corrugating station, said station having said pairs of corrugated rolls in a plane in which said sheeting is fed, the corrugating station further including other pairs of upper and lower corrugated rolls, said pairs of corrugated rolls and said other pairs of corrugated rolls being interchangeable with each other in said plane without interrupting the extrusion moulding of said sheeting.

2. Apparatus for the continuous manufacture of corrugated sheets of a thermoplastic synthetic resin including a synthetic resin sheeting extruder, a polishing and preheating station, a corrugating station, a trimming station, a takeup station, and a cutting station, said corrugating station comprising at least two spaced rows of pairs of corrugated rolls having different corrugated patterns, and means for vertically moving the upper or lower row of pairs of corrugated rolls into a plane in which synthetic resin sheeting is fed.

3. Apparatus as claimed in claim 2 wherein the two spaced rows of pairs of corrugating rolls are mounted in a frame movable vertically to bring the pairs of rolls of a required type into position to receive sheeting for corrugating.

4. Apparatus as claimed in claim 2 wherein said takeup station includes a large diameter roll bearing in use against the lower surface of corrugated sheeting, a first pressing roll disposed above said corrugated sheeting, and having a corrugated pattern corresponding to the corrugated pattern on said corrugated sheeting, and a second pressing roll having a different corrugated pattern, and which is interchangeable with said first pressing roll.

5. A method of manufacturing corrugated sheets of a thermoplastic synthetic resin, continuously, substantially as hereinbefore described with reference to and as shown in Figs. 2, 3 and 4 of the accompanying drawings.

6. Apparatus for the continuous manufacture of corrugated sheets of a thermoplastic synthetic resin substantially as hereinbefore described with reference to and as shown in Figs. 2, 3 and 4 of the accompanying drawings.