WO2005056254A1

WO2005056254A1 - An improved method and apparatus for cutting foam blocks

Info

Publication number: WO2005056254A1
Application number: PCT/AU2004/001669
Authority: WO
Inventors: Kenneth Skovsted Rassmussen
Original assignee: Wintech International Pty Ltd
Priority date: 2003-12-09
Filing date: 2004-11-29
Publication date: 2005-06-23

Abstract

A process and apparatus for cutting an EPS block (7). The block is moved (8) continuously past a cutting station (5), having at least one cutter (6) adapted to cut the block at least partially laterally across an axis of propagation of the blocks. The block is cut with the at least one cutter at the cutting station with the cutting action being controlled to accommodate the motion of the block to achieve a desired cut while maintaining the continuous motion of the block. The cutting station can include vertical, horizontal and multiple cutters. Cutting action can be determined as a function of the motion of the block (11).

Description

AN IMPROVED METHOD & APPARATUS FOR CUTTING FOAM BLOCKS FIELD OF THE INVENTION The invention relates to apparatus and methods for the cutting of foam and polystyrene, and in particular, expanded polystyrene (EPS). In particular, the invention relates to means for more efficient production of profile cut shapes from EPS applied to continuous process models. BACKGROUND OF THE INVENTION Cutting apparatus of the type previously described comprise at least one cutting device designated to make a particular type of cut applied to a block of foam polystyrene or expanded polystyrene (EPS). The block is placed within the apparatus and the cutting device applied to the block whereupon the desired shape is cut from the block. The block is placed within the apparatus either manually or is delivered by a conveyor adapted to move the block into a stationary position. In order to achieve the complex shapes a close coordinate control of the position of the block is required throughout the process and consequently movement of the block is likely to lead to a defective finished product. Whilst the technology related to cutting devices is improving and so the time taken to make a certain type of cut is decreasing, this still does not provide the optimum conditions for the process. It would be most advantageous to maintain a continuous process rather than the stop-start process currently used, as the block moves from cutting station to cutting station. Further difficulties in the art relate to the cost of capital equipment. EPS cutting is generally provided by the linking together of a number of machines, each providing a separate function of the cutting requirement forming a production line. The basic production line will provide separate devices for simple production cutting being essentially horizontal cuts, vertical cuts parallel to the axis of propagation of the block, and vertical cuts lateral to said axis. For more complex contour cutting a further machine with that capability is required for the production line. Such a profile cutting production line would normally extend some thirty metres or more in length, and requires the use of a number of intermediate conveyors to transport the EPS block from machine to machine. Further, as a common requirement is to cut the EPS into blocks actually disposed to the line, that is, cut across the conveyor, then it is necessary to stop the forward flow of the EPS, that is the production line flow, in order to produce these cuts whilst the block is stationary. It is in the stopping of the production line at repeated points in the product flow, and the large amount of floor space required, that lead to the inefficiencies of conventional systems. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an apparatus and method for more efficient and accurate cutting of EPS blocks as compared to the prior art. In a first aspect the present invention provides a process for cutting an

EPS block, including the steps of: moving the block continuously past a cutting station, said cutting station including at least one cutter adapted to cut the block at least partially laterally across an axis of propagation of the block; cutting the block with the at least one cutter at the cutting station, wherein the cutting action is controlled to accommodate the motion of the block to achieve a desired cut while maintaining the continuous motion of the block. With this in mind, the present invention seeks to maintain a cost effective process by continuously processing each block as compared to a stop-start approach which would have the block stopping every time a cut was required. It follows for even relatively simple shapes that to stop the block in order to make a lateral cut will slow production considerably. By maintaining a continuous operation, productivity and cost effectiveness may be raised. The present invention meets this criteria by accommodating the forward advancement of the block during the cut through controlling the motion of the cutter to ensure that the correct cut is made. For instance, in the most simple example, using conventional methods to make a vertical cut would require stopping the block and driving the cutter straight down. With the method of the present invention the absolute direction of the cutter will be somewhat inclined to accommodate the motion, and therefore the degree of inclination will be a function of the speed of the block and the downward motion of the cutter. By controlling the motion of the cutter, relative to the frame of reference of the block, the cut will in fact appear directly vertical. This control may be equally applicable for any cut that is not directly parallel to the axis of propagation of the block with the controller accommodating this motion accordingly. In a preferred embodiment of the present invention, the direction of the at least partially laterally directed cutter may include any one, or a combination of, vertical movement, horizontal movement, or complex motion. The complex motion may include motion in which the cutter provides a profile cut to the block. Reference to the at least partially laterally directed cutter may include profile cutting of complex shapes. For instance, a curve or multiple inclined cut by the profile cutter may have a vector of the cut directed laterally across the axis of propagation of the block, whereas a portion may be parallel to said axis. The controller therefore may control the motion of the cutter as a function of the motion of the block. It is appreciated that the more complex the profile, the more complex will be the algorithm controlling the motion of the cutter. However, the determination of an appropriate algorithm for a predetermined profile and motion of the block falls within the capabilities of the skilled addressee. In a more preferred embodiment of the present invention, the cutting station may accommodate more than one cutter. In a most preferred embodiment of the present invention, the cutting station may include a separate cutter for a horizontal cut, and a second cutter for a vertical cut, both lateral and parallel to the axis of propagation of the block. Further, said separate cutter for the horizontal cut may include a plurality of cutters for effecting a plurality of individual horizontal cuts simultaneously. Thus, in this embodiment the cutting station may accommodate all cutting functions, and demonstrate a capability to shape an EPS block in the desired shape within a single device. Where a conventional production line may accommodate multiple machines having connecting conveyors, in this embodiment cutters are arranged proximate to each other within the same device and so reducing the size of the footprint on the factory floor. Apart from the savings in rent, available floor space etc., the savings in capital expenditure may be considerable. In a further preferred embodiment, the present invention may be configured to selectively switch from a "production line" mode to a "profiling/small batch job" mode, based upon the assembly of cutters selected. A "Production Line" machine is one configured for continuous production flow. A machine configured for profiling/small batch jobs, and more particularly complex profile cutting might be described as a utility machine for both complex cutting which has more work than can be carried out whilst maintaining a constant flow, and also for the similar less complex work that the production line machine may handle, but in smaller quantities. An important differentiation between the two modes is that whilst the profiling/small batch job mode can handle the same work as the Production line mode, it cannot handle it nearly so efficiently. In a more preferred embodiment, the profiling/small batch job mode may be effected by selecting the activation of a composite fast wire-hot wire machine (FWCS). The market splits between companies that generally operate solely on large production batches, and consequently purchase a suite of machines to configure in a row in order to handle each part of the cutting process. This is the upper end of the business scale, ie very large volume work. However, having taken this approach they cannot handle the more complex profile contour cutting that a FWCS can. This is limiting in that when large batch work is not available they may not readily put the equipment to alternative use. Companies that use a FWCS, generally operate in the small to medium end of the business scale. They work on "one off's", complex jobs, and profiling/small batch work. This is limiting in that they cannot step up competitively to larger batch work. In this embodiment of the present invention, the ability to selectively switch between modes may provide a significant operational advantage. As either business type may continue with its favoured job type, but have the ability to switch the machine over to the opposite function, this effectively increases return to either business type. Further, it not just blurs the fundamentals of each business type, but totally removes the reason for each having different fundamentals. In a preferred embodiment there may be a mono-direction conveyor in constant operation in the direction of the production flow. There may be a hot wire (CS) set of posts mounted on a carriage that sits on linear bearing rails and remains parked at the off end of the machine. It may be further be provided with hot horizontal wires for the purpose of slitting the EPS block into various quantities and sizes of horizontal slabs. In a further preferred embodiment there may be a fast wire (FW) set of posts mounted on a carriage, adapted to make vertical cuts. Said posts may sit on the same linear bearing rails as those of the hot wire assembly. In a second aspect the present invention provides an apparatus for cutting an EPS block, including: A moving means for moving the block continuously past a cutting station, said cutting station including at least one cutter adapted to cut the block at least partially laterally across an axis of propagation of the block; A cutting assembly located at the cutting station for cutting the block with the at least one cutter at the cutting station, wherein the cutting action is controlled to accommodate the motion of the block to achieve a desired cut while maintaining the continuous motion of the block. DESCRIPTION OF PREFERRED EMBODIMENTS It will be convenience to further describe the present invention with respect to the accompanying drawings which illustrates a possible arrangement of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention. Figure 1a is a side elevation view of the cutting apparatus in production mode according to one embodiment of the present invention. Figure 1b is a side elevation view of the cutting apparatus in FWCS mode according to a further embodiment of the present invention. Figure 2 is a side elevation view of a block being vertically cut according to a preferred embodiment of the present invention. Figure 3 is a side elevation view of a block undergoing a profile cut according to a further preferred embodiment of the present invention. Figure 1a shows the production mode arrangement 1 according to a preferred embodiment of the present invention. The arrangement includes a fast wire post set (FW) 5 positioned at a suitable starting point, relatively close to the feed end of the conveyor 2, with the wire 6 above the height of the block 7. The mono-directional conveyor 2 is in operation in forward motion 9. A sensor is provided to identify when a new EPS block 7 reaches a critical point. A block 7 of EPS is fed onto the conveyor 2 (positioned accurately across the conveyor width). The conveyor takes the block and carries it to the critical point where the sensor is activated. A cutting cycle 11 then commences (programmed to the product requirements). Whilst the conveyor 2 is still carrying the block forward 8 the FW 5 commences to move forward 12 at the same speed as the conveyor and the wire traverses downwards at a speed greater that the speed of the conveyor. This will produce a vertical cut through the block without having had to stop the production flow. The cutting cycle 11 then returns the wire back to the starting point of its cycle. (This may be by the wire traversing back up the previous vertical cut whilst the FW Posts 5 are still travelling in the direction of the conveyor, and then travelling in a direction opposite to the conveyor back to the starting point, or may by way of travelling against the direction of the conveyor travel, cutting through the bottom of the block, to a point where a new vertical cut can be commenced from the bottom and cutting upwards (the FW changing direction to again travel in the direction of the conveyor). Once through the top of the block the FW posts will then travel in a direction opposite to the conveyor travel back to the starting point. At this time the FW would pause until the next programmed vertical down cut position is reached and the whole cycle would be repeated. The block 7 continues through to the hot wire post 3, having a plurality of cutters 4 adapted to provided horizontal cuts as required to the block 7. Said hot wire post 3 in this arrangement is fixed 10 allowing movement 9 of the conveyor 2 to effect the horizontal cuts. The significance of using an FW for the down cutting is that the production flow would be set at the optimum speed for hot wires cutting the product. This is the speed that the conveyor would be operating at. A FW can cut EPS at a much faster speed than a hot wire. This may be in the order of four times quicker and is what allows the "fly cutting" motion to work efficiently in terms of the minimum distance between potential down cuts. The two examples of cutting cycles are described due to the different efficiencies that each may achieve, and the resulting minimum block cut size that may be achieved. Figure 1b shows the present invention according to another preferred embodiment of the present invention. Here the arrangement 20 is selected for a profiling/small batch job, such as full contour cutting. In this arrangement, the FW 5 is driven up to the hot wire post set (CS) 3 and the carriages are locked together. The conveyor 2 remains stationary and the machine provides the necessary horizontal 21 motion, which in combination with the CS movement 23 or FW movement 22 provide the required action for accurate contour cutting of the block 7. Figures 2 and 3 show elevation views of different types of cutting actions according to the present invention. In both cases an EPS block 100 is travelling upon a conveyor 105 in a continuous motion. The continuous motion is represented by a horizontal vector 110 defining both direction and speed. In Figure 2 specifically, a cutter which may be a fast wire 115, has defined a vertical path 120 through the block 100 so as to present a vertical cut. Because of the block vector 110, the actual motion of the fast wire 115 must match the block vector 110 with equivalent vector 130. Because the desired cut 120 is vertically down, the downward vector 135 of the fast wire 115, together with the equivalent vector 130 defines an actual resultant path 140. Thus, from the block frame of reference the downward cut 120 is vertical, however the global frame of reference for the path of the fast wire 115 is actually represented by a resultant vector 140. Figure 3 shows the same block 100, again moving on a horizontal vector

110 upon the conveyor 105. In this instance however, the desired shape is a more complex path 145, with the diagram showing the progressive stages of the fast wire 150, 175, 200. At each stage because the path of the wire varies along the complex path 145 the controller implements an algorithm corresponding to the path which will vary the resultant vector of the wire according to the desired shape. At the first stage the desired cut is an inclined path downward and opposed to the motion of the block 110. Thus, the horizontal vector 165 must be marginally less than the forward vector 110 of the block to permit the forward advancement of the block to drive against the wire 150. In combination with a corresponding downward motion 160 this yields a resultant vector 170. The resultant vector in defining the motion of the wire 150 in a global frame of reference is defined 155. At a second point along the path 145 the wire 175 is travelling substantially downwards. Again, a vector diagram 180 defines the equal horizontal vector 190 to match the block vector 110. The downward vector 185 from the block frame of reference then yields a resultant vector 195 defining the motion of the wire 175 from a global frame of reference. A third stage of the path 145 locates the wire 200 at a point where the path is forward and fractionally downward on the block. Consequently the vector diagram 205 defines a small downward vector 210. As the wire must travel faster than the resulting motion of the block in order to achieve a forward horizontal movement there is a greater horizontal vector 215 which together with the downward vector 210 forms a resultant vector 220 angled considerably forward and downward. An analysis of the path of the wire, being a function of the desired shape, speed of the wire and speed of the block will permit the skilled addressee to formulate an appropriate algorithm to model the required motion of the wire.

Claims

CLAIMS:

1. A process for cutting an EPS block, including the steps of: moving the block continuously past a cutting station, said cutting station including at least one cutter adapted to cut the block at least partially laterally across an axis of propagation of the block; cutting the block with the at least one cutter at the cutting station, wherein the cutting action is controlled to accommodate the motion of the block to achieve a desired cut while maintaining the continuous motion of the block.

2. A process according to claim 1 , wherein the direction of the at least partially laterally directed cutter includes any one, or a combination of, vertical movement, horizontal movement, or complex motion.

3. A process according to claim 2, wherein the complex motion includes motion in which the cutter provides a profile cut to the block.

4. A process according to any one of the preceding claims, wherein the at least partially laterally directed cutter is configured for profile cutting of complex shapes such as curves.

5. A process according to claim 4, wherein the at least partially laterally directed cutter is configured for making multiple inclined cuts by the profile cutter having a vector of the cut directed laterally across the axis of propagation of the block and a vector parallel to said axis.

6. A process according to any one of the preceding claims, wherein control of the motion of the cutter is determined as a function of the motion of the block.

7. A process according to any one of the preceding claims, wherein the cutting step includes cutting using two or more cutters.

8. A process according to claim 7, wherein cutting is carried out using a separate first cutter for a horizontal cut, and a second cutter for a vertical cut, both lateral and parallel to the axis of propagation of the block.

9. A process according to claim 8, wherein said horizontal cutting utilises a plurality of cutters for effecting a plurality of individual horizontal cuts simultaneously.

10. A process according to any one of claims 7 to 9, wherein the cutters are arranged proximate to each other within the same device.

11. A process according to any one of the preceding claims, wherein the cutting station is selectively switchable from a production line mode accommodating continuous production flow to a profiling/small batch job mode configured for profiling/small batch jobs such as complex profile cutting.

12. A process according to claim 11 , wherein the profiling/small batch job mode is effected by selecting the activation of a composite fast wire-hot wire machine (FWCS).

13. A process according to any one of the preceding claims, wherein the cutting station further includes a mono-direction conveyor for constant operation in the direction of the production flow.

14. A process according to any one of the preceding claims, wherein the cutting step includes making horizontal cuts with a hot wire (CS) set of posts and/or making vertical cuts with a fast wire (FW) set of posts.

15. A process according to claim 14, wherein the hot wire set of posts and/or the fast wire (FW) set of posts are/is mounted for operation on a carriage on linear bearing rails.

16. An apparatus for cutting an EPS block, including: a moving means for moving the block continuously past a cutting station, said cutting station including at least one cutter adapted to cut the block at least partially laterally across an axis of propagation of the block; a cutting assembly located at the cutting station for cutting the block with the at least one cutter at the cutting station, wherein cutting is controlled to accommodate the motion of the block to achieve a desired cut while maintaining the continuous motion of the block.

17. An apparatus according to claim 16, wherein the cutting station accommodates two or more cutters.

18. An apparatus according to claim 17, wherein the cutting station includes a separate first cutter for a horizontal cut, and a second cutter for a vertical cut, both lateral and parallel to the axis of propagation of the block.

19. An apparatus according to claim 18, wherein said cutter for the horizontal cut includes a plurality of cutters for effecting a plurality of individual horizontal cuts simultaneously.

20. An apparatus according to any one of claims 17 to 19, wherein the cutters are arranged proximate to each other within the same device.

21. A process according to any one of claims 16 to 20, wherein the cutting station is configured to selectively switch from a production line mode accommodating continuous production flow to a profiling/small batch job mode configured for profiling/small batch jobs such as complex profile cutting.

22. An apparatus according to claim 21 , wherein the profiling/small batch job mode is effected by selecting the activation of a composite fast wire-hot wire machine (FWCS).

23. An apparatus according to any one of claims 16 to 22, wherein the cutting station further includes a mono-direction conveyor for constant operation in the direction of the production flow.

24. An apparatus according to any one of claims 16 to 23, wherein the cutting station includes a hot wire (CS) set of posts arranged to make horizontal cuts and/or a fast wire (FW) set of posts arranged to make vertical cuts.

25. An apparatus according to claim 24, wherein the hot wire set of posts and/or the fast wire (FW) set of posts are/is mounted on a carriage on linear bearing rails.