GB1590231A

GB1590231A - Method of manufacturing stakes

Info

Publication number: GB1590231A
Application number: GB9071/77A
Authority: GB
Original assignee: AIR SCOOTERS Ltd
Current assignee: AIR SCOOTERS Ltd
Priority date: 1978-03-03
Filing date: 1978-03-03
Publication date: 1981-05-28

Description

(54) A METHOD OF MANUFACTURING STAKES (71) We, AIR SCOOTERS LIMITED (trading as WILLINGER MACHINERY Co.), a British Company, of 45 Queensgate Gardens, London, S.W.7, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to method of manufacturing stakes and is particularly suitable for the processing of polymer waste composed of a mixture of polymers.

According to a first aspect of the present invention there is provided a method of manufacturing pointed stakes comprising the steps of feeding a molten or semi molten mass of the polymer material to continuously advancing forming elements which cooperate throughout a forward run thereof to forward the material whilst conforming it to, holding it conformed in or conforming it to and holding it conformed in a predetermined cross-section to produce a continuous or substantially continuous delivery of material conformed to the predetermined crosssection, forming the polymer material into stake lengths and providing each of the stake lengths with a point, thereby to form a stake.

According to a second aspect of the present invention there is provided a machine for use in the manufacture of pointed stakes, the machine comprising forming means to which a molten or semi molten mass of the material is delivered, the forming means including continuously advancable forming elements which in operation cooperate throughout a forward run thereof to forward the material whilst conforming it to, holding it conformed in, or conforming it to and holding it conformed in a predetermined cross-section, form the material into stake lengths and provide each stake length with a point, thereby to produce a continuous or substantially continuous delivery of stakes.

Preferably the material delivered by the forming elements is then passed through a cooling zone where it is subjected to rapid cooling.

The continuously advancing forming elements preferably comprise a pair of endless belts or chains which have forward runs in which the outer surfaces of the two belts or chains run in contact with each other and are profiled to conform the material passing between them to the predetermined cross-section. Usually the material is fully conformed or conformed to a very large degree before it reaches the end of the forward run. Thugs, in general, the material is held conformed to the predetermined crosssection throughout a substantial length of its travel. Furthermore, the material can be provided to the entry end of the forward run with a cross-section which is the same, or substantially the same as the said predetermined cross-section in which case it can occur that the material is held conformed for the entire length of the forward run.

Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 is a schematic side elevation of part of a processing machine for manufacturing from polymer material stakes suitable for use in supporting vines growing in vineyards, Fig. 2 is a continuation to the right of Fig. 1 of the side elevation illustrated in Fig. 1, showing a further part of the machine, Fig. 3 is a side elevation partly in section of the entry end of a forming conveyor forming part of the machine shown in Fig. 1, Fig. 4 is a section taken on the line IV-IV in Fig. 3, Fig. 5 is a section taken on the line V-V in Fig. 4, Fig. 6 is a side elevation of vine stake made from blanks produced by the machine illustrated in Figs. 1 to 5, Fig. 7 is a section taken on the line VII--VII in Fig. 6, and Fig. 8 is a schematic part sectional side elevation of part of a processing machine according to a further embodiment of the invention.

Referring first to Fig. 1 polymer material in the form of a molten or semi molten mass is delivered to a vertical cylinder 11 whose temperature can be controlled and which is fitted with a motor driven reciprocating screw. The cylinder 11 is formed with an upper extension 12 which serves as an accumulator. Gas sing of the molten mass of material is effected in the cylinder 11 and the downward movement of the rotating screw extrudes the material at low pressure through a die 13 to produce a continuous supply 14 of the molten material.

The molten material 14 is fed direct into the nip between a pair of driven performing rollers 15 and 16, the contacting peripheral surfaces of which may be profiled to form the material passing therethrough into a tow of roughtly cruciform cross-section. The tow 17 is carried round on the surface of the roller 16 and into the nip between the roller 16 and a further preforming roller 18 having a peripheral contacting surface with a profile of the same shape as that of the peripheral surface of the roller 15.

The tow 17 leaving the preforming rollers 16 and 18 passes to the entry end of a continuously advancing forming conveyor 19, which comprises a pair of endless chains 20 and 21 having cooperating forward runs between which the tow 17 is advanced, each conveyor chain being formed with a plurality of blocks adjacent ones of which mate with each other along the forward run of the chain and provide a continuous surface along which the tow is advanced. As will hereinafter be described in detail, the contacting surfaces of opposing blocks of the two chains are profiled to provide throughout the forward runs of the chains a continuous channel of cruciform cross-section to which the tow is conformed while being advanced therealong. The cross-section of the tow 17 as it passes to the entry end of the conveyor 19 is approximately the same as the cross-section into which it is conformed while being advanced along the conveyor.

The length of the forward run of the chains is so chosen as to provide support for the tow during a period sufficient to cool and harden it so that it leaves the forward run of the chains conformed to the cruciform cross-section imposed upon it.

The tow 17 leaving the forming device 19 passes into a water cooling tank 23 through which it is advanced on the upper run of an endless conveyor belt 24 driven from a shaft 25. The cooling tank comprises a plurality of upper and lower water nozzles 26 arranged in spaced relation along the length of the tank and supplied with water to form a cooling spray over the upper and lower runs of the conveyor belt 24. The tow 17 on leaving the cooling tank 23 passes through an air knife device 27 which proVides for further cooling of the tow and then through a travelling saw device 28 in which the completely hardened tow 17 is sawn through at predetermined intervals therealong to produce a succession of individual bars of cruciform cross-section. The bars thus formed by the travelling saw device 28 are fed to a stacker 29 (Fig. 2) where they drop into a container one upon the other under gravity.

Referring now to Figs. 3, 4 and 5 the conveyor chains 20 and 21 are guided round sprocket wheels 30 and 31 for entry into their forward runs where they are supported by rollers 32 provided on the chains and riding in channels provided in support rails 33 and 34. The links 35 of the chain 20 carry forming blocks 36, 361 and the links of the chain 21 carry forming blocks 37, 371, the forming blocks 36 and 37 and the blocks 361 and 371 coming into contact in the forward runs of the chains as illustrated in Figs. 4 and 5 of the drawings.

As best seen in Figs. 4 and 5 the contacting surfaces of the blocks 36 and 37 and the blocks 361, 371 are profiled at 38 and 39 to produce a continuous channel 40 of cruciform cross-section. In addition the blocks 36 and 361 are recessed at 41 and 42 to provide two further channels extending throughout the forward run of the two chains. The blocks 361 and 371 are furthermore provided with projections 43 and 431 which in the forward run of the chains come into registration for the purpose of forming at predetermined intervals laterally extending slots in the tow being conformed to the cruciform cross-section of the channel 40.

In operation the tow 17 delivered by the rollers 16 and 18 in Fig. 1 is fed into the entry end of the forward run of the chains 20 and 21 and advanced in the channel 40 where it is compressed to conform to the cruciform profile of the contacting blocks, excess material, if any, during the conforming operation being expelled into the channels 41 and 42 for removal therefrom at the delivery end of the forward run. In conforming the tow 17 to the cruciform crosssection the material forming the tow is prevented from occupying the space taken by the contacting projections 43 and 431, producing in the blank at the delivery end slots laterally extending into opposing ribs of the blank.

The bars of cruciform cross-section delivered to the stacker 29 are then subjected to one or more finishing operations to produce a vine stake of the form shown in Figs. 6 and 7. As will be seen the lowermost end of the stake is worked to form serrated ribs reducing to a sharp point at the end of the stake with the other end being provided with slots 44 arranged at predetermined intervals along the length of two opposing ribs of the stake.

It will be appreciated that the projections 43 and 431 on the blocks 36' and 371 can be omitted and the bars of cruciform crosssection provided with the required slots 44 by a subsequent machining operation to produce the stake shown in Figs. 6 and 7.

Furthermore, it will be understood that the die 13 need not be arranged to extrude downwardly but can extrude upwardly or in any other convenient direction.

Part of a further embodiment of the invention is illustrated in Fig. 8, which embodiment is particularly suitable for processing polymer waste. Parts common to the embodiment of Fig. 8 and the embodiment of Figs. 1 to 5 bear the same reference numberals. A motion or semi molten mass of polymer waste is delivered from a compounding extruder 46 having a multi-orifice die 45 to a screw extruder 11 which extrudes the material from a die 13 of roughly cruciform cross-section to produce the tow 17 which is fed direct to the forming conveyors 19. The screw extruder 11 has means for controlling its temperature, a port 5a and a vent 51. Passage through the multiorifice die 45 liberates from the polymer waste gas and excess moisture which is then removed through a vent 52. Further gas and excess moisture can be removed from the material through the vent 51. Thus the vent 51 and the combination of the die 45 and vent 52 each constitutes a degassing means Extraction of gas and moisture from vents 51 and 52 can be assisted by connecting the vents to the input of a suitable pump.

Effective degassing of the waste polymer material produces an improved starting material for extrusion through the die 13 and for forming device 19. The port 50 can be used in known manner to introduce to the flow of material through the screw extruder 46, if it is desired to do so, such materials as additives, colourants and fillers.

In another embodiment according to the invention a pair of driven preforming rollers 48 and 49 are provided in advance of the forming device 19 as illustrated in broken line in Fig. 8 to improve the formation of the tow prior to its delivery to the device 19.

The rollers 48 and 49 or a pair of postforming rollers not illustrated may if desired be arranged downstream of the device 19 to provide a finishing forming operation for the tow 17.

In yet another embodiment of the invention not illustrated the screw extruder 11 of the arrangement shown in Fig. 8 is modified by substituting for the die 13 a preforming cross-head die which provides for the formation of a core of cruciform crosssection composed of the material delivered by the main extruder screw and obtained from a polymer waste supply, sheathed by an outer coating or layer of a polymer delivered to the die by an auxiliary screw extruder to provide a good surface finish to the end product. The polymer providing the surface layer may be a pure polymer such as PVC or a polyolefin, giving where desired an attractive colour and feel to the product produced. The composite tow from the cross-head die is processed in the same manner as the tow 17 in the machine illustrated in Figs. 1 to 4 to produce a vine stake of superior finish.

In still yet another embodiment of the invention, the tow 17 obtained from molten or semi-molten polymer waste delivered by the screw extruder 11 in the Fig. 8 arrangement is passed to the forming conveyor 19 where it is processed as hereinbefore described, but on leaving the device 19 and prior to entry into the cooling tank 23 it is arranged to pass as a core through a postforming cross-head die also supplied with a pure polymer from an auxiliary screw extruder which sheaths the core with an ou'ter layer to provide a superior surface finish for the tow 17.

If desired, the tow 17 prior to entry to the cooling tank 23 may be passed through a sizing and cooling die. Furthermore, it may be found advantageous for some purposes to replace the cooling tank 23 by a water cooling bath in which the tow 17 is completely immersed in the cooling water.

It will be appreciated that by an appropriate shaping of the blocks 36, 37 at preselected intervals along the belt complete stakes of predetermined length can be produced during the forming operation performed by the device 19, the end of one stake being reduced to a point by one or more pairs of appropriately shaped blocks 36 and 37, with excess material being channelled to form a head on the next stake.

Clearly, Iby rearranging the positions of the end-shaping blocks along the lengths of the chains the length of the final product can be varied as desired.

It will furthermore be appreciated that stakes or other articles can be produced having cross-section other than cruciform and that a wide variety of ancillary operations can be performed by the blocks.

The method and machine according to the present invention make possible the manufacture of stakes for supporting above the ground and substantially parallel with the ground at least two wires, and which define at least two slots each of which has an open end to receive one of the wires. The present invention further makes possible the manufacture of such a stake with a single conforming process which defines both the cross-section and the slots of the stake. The material of the stake is preferably a synthetic polymeric material and such material can comprise material which is a waste pro duct of an industrial process. When the stakes are to be used for supporting vines in vineyards there will normally be at least four slots on each stake and the slots will be arranged in pairs spaced apart from one another along the length of the stake at intervals of, for example, 15 cms. The slots are preferably located on two opposed ribs on the stake, and the cross-section can be of cruciform shape. Figs. 6 and 7 of the accompanying drawings illustrate an example of the construction contemplated. In order to receive and support the wires the slots are conveniently of a shape such that the slots extend outwardly from the longitudinal axis of the stake at an angle of 45" or approximately 45" to the longitudinal axis of the stake.

WHAT WE CLAIM IS:- 1. A method of manufacturing pointed stakes comprising feeding a molten or semimolten mass of polymer material to continuously advancing forming elements which cooperate throughout a forward run thereof to forward the material whilst conforming it to, holding it conformed in, or conforming it to and holding it conformed in a predetermined cross-section to produce a continuous or substantially continuous delivery of material conformed to the predetermined cross-section, forming the polymer material into stake lengths and providing each of the stake lengths with a point, thereby to form a stake.

2. A method according to claim 1 ineluding the step of extruding the material through a die to provide the molten or semimolten mass as a shaped tow having a cross-section which is the same as or approximately the same as, the said predetermined cross-section.

3. A method according to claim 2 including the step of flowing the material through a degassing means before it is extruded through the die.

4. A method according to claim 2 or 3 including the step of rolling the tow between a pair of driven preforming rollers located upstream of the forming elements.

5. A method according to any one of the preceding claims wherein the conformed material is subjected to the step of rapid cooling by contacting it with a flow of liquid coolant.

6. A method according to claim 5 wherein the step of rapid cooling is effected by complete immersion of the material in the liquid coolant.

7. A method according to claim 5 or 6 including the step of rolling between a pair of driven post-forming rollers the material conformed by the forming elements before it is subjected to the step of rapid cooling.

8. A method according to claim 5, 6 or 7 including the step of passing the material conformed by the forming elements through a sizing and cooling die before it is subjected to the step of rapid cooling.

9. A method substantially as hereinbefore described with reference to Fig. 1 to 5 of the accompanying drawings.

10. A method substantially as hereinbefore described with reference to Fig. 8 of the accompanying drawings.

11. A machine for use in the manufacture of pointed stakes, the machine comprising forming means to which a molten or semi-molten mass of the material is delivered, the forming means including continuously advanceable forming elements which in operation cooperate throughout a forward run thereof to forward the material whilst conforming it to, holding it conformed in, or conforming it to and holding it conformed in a predetermined cross-section, form the material into stake lengths and provide each stake length with a point, thereby to produce a continuous or substantially continuous delivery of stakes.

12. A machine as claimed in claim 11 including a main extruder for extruding the material through a die to provide the molten or semi-molten mass of material as a shaped tow having a cross-section which is the same as, or approximately the same as, the said predetermined cross-section.

13. A machine as claimed in claim 12 iccluding a compounding extruder provided with a multi-orifice die for degassing the material and for supplying the material to the main extruder.

14. A machine as claimed in claim 12 or 13 including a port for introducing additional materials into the flow of polymer material through the main extruder.

15. A machine as claimed in any one of claims 12 to 14 including a pair of driven preforming rollers for rolling the tow before it is fed to the forming elements.

16. A machine as claimed in any one of claims 12 to 15 including a preforming cross-head die for receiving as a core the material delivered by the main extruder, and for receiving polymer from a pre-forming auxiliary extruder to sheath the core with an outer layer or coating of the polymer.

17. A machine as claimed in any one of claims 11 to 16 including at least one nozzle to provide a spray of a liquid coolant to contact the conformed material.

18. A machine as claimed in any one of claims 11 to 16 including a bath for liquid coolant in which the conformed material can be totally immersed.

19. A machine as claimed in claim 17 or 18 including a pair of driven post-forming rollers located upstream of the nozzle or bath and downstream of the forming elements.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. duct of an industrial process. When the stakes are to be used for supporting vines in vineyards there will normally be at least four slots on each stake and the slots will be arranged in pairs spaced apart from one another along the length of the stake at intervals of, for example, 15 cms. The slots are preferably located on two opposed ribs on the stake, and the cross-section can be of cruciform shape. Figs. 6 and 7 of the accompanying drawings illustrate an example of the construction contemplated. In order to receive and support the wires the slots are conveniently of a shape such that the slots extend outwardly from the longitudinal axis of the stake at an angle of 45" or approximately 45" to the longitudinal axis of the stake. WHAT WE CLAIM IS:-

1. A method of manufacturing pointed stakes comprising feeding a molten or semimolten mass of polymer material to continuously advancing forming elements which cooperate throughout a forward run thereof to forward the material whilst conforming it to, holding it conformed in, or conforming it to and holding it conformed in a predetermined cross-section to produce a continuous or substantially continuous delivery of material conformed to the predetermined cross-section, forming the polymer material into stake lengths and providing each of the stake lengths with a point, thereby to form a stake.

20. A machine as claimed in claim 17

or 18 including a sizing and cooling die located upstream of the nozzle or both and downstream of the forming elements.

21. A machine as claimed in any one of claims 11 to 18 including a post-forming cross-head die for receiving as a core the material delivered by the forming elements, and for receiving polymer from a postforming auxiliary extruder to sheath the core with an outer layer or coating of the polymer.

22. A machine as claimed in any one of claims 11 to 21 wherein the forming elements comprise first and second endless belts or chains which have forward runs in which the outer surfaces of the two belts or chains run in contact with each other and are profiled to conform the material passing between them to the predetermined crosssection.

23. A machine as claimed in claim 22 wherein the first and second endless belts or chains comprise first and second pluralities of forming blocks.

24. A machine as claimed in claim 23 wherein one or both of the first and second pluralities of forming blocks is or are provided with recesses to accommodate material which is excess to the conforming operation.

25. A machine as claimed in claim 23 or 24 wherein the first and second pluralities of forming blocks taken together include a first and a second projection for forming at predetermined intervals laterally extending slots in the material being conformed.

26. A machine as claimed in claim 25 wherein the first projection is provided on the said first plurality of forming blocks and the second projection is provided on the said second plurality of forming blocks, the positions of the first and second projections being such that, in the forward run of the belts or chains, the first projection and the second projection come into registration one with another.

27. A machine as claimed in any one of claims 22 to 26 wherein the first and second pluralities of forming blocks comprise blocks which are so shaped as to conform the molten or semi-molten material to the shape of the pointed end of the stake.

28. A machine substantially as hereinbefore described with reference to Figs. 1 to 5 of the accompanying drawings.

29. A machine substantially as hereinbefore described with reference to Fig. 8 of the accompanying drawings.

30. A stake made of a synthetic polymeric material and produced by a method according to any one of claims 1 to 10 or a machine as claimed in any one of claims 11 to 29.

31. A stake as claimed in claim 30 wherein at least a part of the synthetic polymeric material is a waste product of an industrial process.

32. A stake as claimed in claim 30 or 31 for supporting above the ground and substantially parallel with the ground and with each other a first and a second wire wherein the stake is provided with a first open-ended slot to receive the first wire and a second open-ended slot to receive the second wire.

33. A stake as claimed in claim 32, the manufacture of which involves a conforming process which defines both the crosssection and the said first and second slots of the stake.

34. A stake as claimed in any one of claims 2 or 33 wherein the said first and second slots are arranged as a pair in that they are located on opposite sides of the stake and at the same distance, or substantially the same distance, along the length of the stake, and wherein the stake is provided with one or more pairs of further slots which are spaced from the first and second slots along the length of the stake and which are for supporting further wires parallel or substantially parallel to the first and second wires.

35. A stake as claimed in claim 34 having first and second longitudinal ribs located on opposite sides of the stake, the ribs including the said first, second and further slots.

36. A stake as claimed in claim 35 having a cross-section which is of cruciform shape.

37. A stake as claimed in any one of claims 34 to 36 wherein the pairs of slots are spaced from one another along the length of the stake by about 15 cm.

38. A stake as claimed in any one of claims 2 to 37 wherein the shape of the slots is such that they extend outwardly from the longitudinal axis of the stake at an angle of 45" or approximately 45" to the longitudinal axis of the stake.

39. A stake substantially as hereinbefore described with reference to Fig. 6 and 7 of the accompanying drawings.