CA1081423A

CA1081423A - Extruding followed by cooling and lubricating of the extrudate

Info

Publication number: CA1081423A
Application number: CA264,768A
Authority: CA
Inventors: Heung T. Kim; Robert A. Hassel; John S. Kowalczyk
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1975-12-08
Filing date: 1976-11-01
Publication date: 1980-07-15
Also published as: BE849133A; IT1069867B; NL7613075A; JPS5269969A; FR2334490A1; DE2652387A1

Abstract

EXTRUDING
ABSTRACT OF THE DISCLOSURE

Method and apparatus for plasticizing thermo-plastic material, advancing the extrudate through a die member to a desired size and shape, and thence cooling the extrudate immediately at the die member that is in-sulated from the cooling means. A cooling and sizing device is downstream from the die member to facilitate the molding of the extrudate to the final size and shape.

Description

1(~81~Z3 This invention relates to plastic molding and more particularly to a new and improved method and apparatus for extruding and sizing thermoplastic materials.
In the extrusion process of thermoplastic materials, reliance is made on the die means for shaping the product from the extruder. In certain instances where high crystalline material is extruded a sizing fixture downstream from the die member is positioned fully within a cooling or vacuum chamber or tank in a fluid tight manner to facilitate the final sizing process. Improvements in the sizing process have been directed to improvements in the separate external sizing fixture.
The present invention is directed to a new sizing technique which in addition to improving the sizing quality has markedly improved the output particularly in thermoplastic materials such as polyurethanes which are fluidal in nature with very little melt strength even at relatively low melt temperatures due to their high crystalline structure which makes the handling of the melt very difficult. In addition, materials of high crystalline structures such as polyurethanes have a very tacky melt making it difficult to size even in the separate sizing device downstream from the extruder.
According to the invention there is provided the method of forming a continuous elongated thermoplastic article comprising the steps of plasticating thermoplastic material, advancing extrudate through a die member, immediately applying a coolant directly to the outer surface of the extrudate to lower the surface temperature and provide a lubricant to the outer surface of the extrudate as the extrudate issues from the die member while insulating the die member directly from said coolant, and thence simultaneously sizing and cooling said extrudate to its finished size downstream of said die member.

In another aspect of the invention there is provided~

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an apparatus for controlling an extrudate comprising an extruder, a die member at one end of said extruder with a die opening therein for shaping said extrudate, a cooling sleeve mounted adjacent to said die me~ber, said sleeve having an inner peri-pheral surface, insulation means interposed between said die mer~er and said cooling sleeve and abuttingly contacting said cooling sleeve and said die member, said cooling sleeve having an aperture larger in diameter than said opening of said die :~
member and having its axis coincident with the axis of said opening of said die member, said cooling sleeve having an :
annular cooling chamber, said sleeve having an inlet and an outlet opening communicating with said cooling chamber to circulate cooling medium therethrough, said cooling sleeve having a plurality of spraying bore~ adjacent to said die member extending from said inner peripheral surface of said sleeve to said cooling chamber for directing a spray of cooling medium outwardly through said bores onto the outer surface of-the extrudate passing adjacent to said inner peripheral surface of said cooling sleeve.
In particular the invention contemplates an apparatus and method which mounts a cooling sleeve on the die member of an extruder with insulation means therebetween and with the : aperture of the sleeve slightly larger than the configuration ~ of the opening in the die member. The ~. .- ~ .
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~ 10814Z3 cooling sleeve has cooling fluids circulating therethrough and may selectively have bores around the inner peripheral surface of the aperture to provide cooling and lubricating medium to the extrudate. A cooling and sizing tank may be placed down-stream of the extrudate to provide the final sizing of the extrudate.
The invention is further illustrated in particular and preferred embodiments by reference to the accompanying drawings in which:
Fig. 1 is a side elevational view of an extruder and supporting apparatus.
Fig. 2 is a front elevational view of the cooling sleeve shown in Fig. 1.
Fig. 3 is a cross sectional view taken along line 3-3 of Fig. 2 of a portion of the die member and cooling sleeve showing the extrudate.
Fig. 4 is a cross sectional view of a modified form of the cooling sleeve.
Fig. 5 is a front elevational view of another modified form of the cooling sleeve.
Fig. 6 is a cross sectional view taken along line 6-6 of Fig. 5 of the modified form of the cooling sleeve.

Referring to the drawings wherein like reference , characters designate like or corresponding parts throughout the several views, there is shown in Fig. 1 a plasticizing and extru-sion means 10 having a hopper 11 and an extruder 12 driven by a motor 13 supported in a base 14. A die member or die means 15 is suitably connected to the extruder 12 to shape the article 18 to the configuration , . , .

~814Z3 desired. The die member 15 has a die opening 16 (Fig. 3) that is contoured to the shape of the article desired. me completed shaping and sizing of the ex-truded article 18 in the case of low melt temperature plastic materials such as polyurethane is accomplished by the passage of the extruded article 18 through a sizing fixture 20 in a cooling and sizing tank 22, The sizing fixture 20 is illustrated generally only and is suitably mounted within a fluid chamber 21 of the cooling and sizing tank 22, the details of construction of which are well in the art. me inlet -to the chamber 21 is in the front endwall 23 with a suitable exit means in the other end wall of the tank 22. Seals are provided to prevent the loss of fluid from ~he chamber 21. me chamber 21 is filled to the proper height with a cooling fluid constantly flowing through an inlet conduit 24 and exiting via outlet con-duit 25. me cooling fluid encompasses the sizing fixture 20 in such flowing action while coming in con-tact with the extrudate 18 passing through the chamber 21. Vacuum means are provided for the sizing fixture 20 in a manner old and well-known in the art.
Suitably attached to the die member 15 is a cooling sleeve member or cooling means 30 that is rec-tangular in configuration having a cooling chamber 31 with an inlet conduit 32 and exhaust conduit 33. Cooling fluid is circulated continuously through the sleeve member 30 to maintain a controlled temperature in a manner old and well-known in the art. Sleeve member 30 has a central aperture 34 centrally therethrough, which aperture 34 is , ~

10814Z~
centrally therethrough, which aperture 34 is slightly larger than the opening 16 in die member 15. Interposed between the outermost end portion of die member 15 and rearward end portion of sleeve 30 is an insulating disk or lnsulating member 36. The aperture 34 of cooling sleeve member 30 tapers rearwardly to substantially the same size as opening 16 in die member 15. A plurality of circumferentially spaced bores 37 extend from the inner peripheral surface of aperture 34 to the chamber 31 to provide a means for distributing a fine spray of cooling fluid to the outer surface of the extrudate as it issues out of the die member 15. In certain instances the exhaust conduit 33 may be closed to maintain suffi-~ent pressure on the fluid dispersed via apertures 34.
In the operation of the apparatus and the method, the extruded plastic article 18 is formed in the extruder 11, which extruded article issues from the extruder via the die member 15 in the shape determined by the con-figuration of the die opening 16. As the extrudate passes through the aperture of the cooling sleeve 31, a fine spray is directed out of the respective spaced bores 37 onto the moving extrudate 18. Pressurized cooling fluid directed into chamber 31 via inlet conduit 32 circulates through the chamber 31 and is exhausted via conduit 33 while a portion of such fluid is diverted as a spray through bores 37. me spray which may be water, air, or a mixture of water and air in addition to cooling the ex-trudate acts as a lubricant to facilitate the passage of the extrudate. The water spray forms a thin water film between the extrudate and the opening of the cooling sleeve. Such action immediately lowers the surface tem-perature of the extrudate 18 as it is directed to the cooling and sizing tank 22, thereby reducing materially the tackiness of the extrudate and increases tremendously the melt strength of the material enhancing the ability to handle the extrudate, facilitating the proper sizing even at high output rates.
The cooling and sizing tank provide~ the mean~ for the final cooling and sizing where necessary as in the case of poly-urethane products.
A modification of the apparatus is shown in Figures 4 and 6, wherein a modified form of the cooling sleeve is shown attached in a suitable manner to die member 15. The embodiment of Figure 4 is similar in all aRpects to that of the original embodiment disclosing cooling sleeve me~ber 30', chamber 31', insulating disc 36', however in lieu of the spaced bores 37, a porous sintered metal portion 50 is located therein which porous portion allows the pressurized water to flow as a fine spray onto the moving extrudate as in the original embodiment.
Thus cooling sleeve member 30' has a plurality of bores having a porous sintered metal throughout their length to facilitate movement of cooling fluid from chamber 31' to the apert~re 34.
The modification qhown in Figs. 5 and 6 di~closes a cooling sleeve 51 which is shown as having a rectangular configuration with a cooling chamber 52 having an inlet conduit 53 and exhaust conduit 54. Cooling fluid is circulated continuously through the sleeve member 51 to maintain a controlled temperature thereof in a manner old and well known in the art. As in the other embodiments, a disk 55 of insulating material is interposed between the die mem~er 15 and the cooling sleeve member 51 to prevent the - -. . , transfer of heat therebetween. Sleeve member 51 has acentral aperture 56 that is located centrally therein of a configuration slightly larger than the opening in the die member 15.
It will be apparent that although a specific embo~iment and certain modification of the invention have been described in detail, the invention is not limited to the specifically illustrated and described constructions since variations may be made without departing from the principles of the invention.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. The method of forming a continuous elongated thermo-plastic article comprising the steps of plasticating thermo-plastic material, advancing extrudate through a die member, immediately applying a coolant directly to the outer surface of the extrudate to lower the surface temperature and provide a lubricant to the outer surface of the extrudate as the extrudate issues from the die member while insulating the die member directly from said coolant, and thence simultaneously sizing and cooling said extrudate to its finished size down-stream of said die member.

2. The method of forming a continuous elongated thermo-plastic article as set forth in claim 1, wherein said immediate applying of a coolant is the direct spraying with water of said extrudate as the extrudate issues from said die member.

3. The method of forming a continuous elongated thermo-plastic article comprising the steps of plasticating thermo-plastic material, extruding a thermoplastic material through an extruder die; cooling said extrudate immediately as it issues from said die by circulating a coolant through a sleeve that encompasses said extrudate; quenching the outer surface of said extrudate by insulating said sleeve from said die by interposing insulation means between said sleeve and said die which abuttingly contacts both said sleeve and said die cooling and lubricating the outer surface of said extrudate by diverting a portion of the coolant from said sleeve directly onto said extrudate as it moves through said sleeve to form a layer of coolant and lubricant therebetween; and thence down-stream from said cooling simultaneously sizing and cooling said extrudate to its finished shape and size.

4. An apparatus for controlling an extrudate comprising an extruder, a die member at one end of said extruder with a die opening therein for shaping said extrudate, a cooling sleeve mounted adjacent to said die member, said sleeve having an inner peripheral surface, insulation means inter-posed between said die member and said cooling sleeve and abuttingly contacting said cooling sleeve and said die member, said cooling sleeve having an aperture larger in diameter than said opening of said die member and having its axis coincident with the axis of said opening of said die member, said cooling sleeve having an annular cooling chamber, said sleeve having an inlet and an outlet opening communicating with said cooling chamber to circulate cooling medium there-through, said cooling sleeve having a plurality of spraying bores adjacent to said die member extending from said inner peripheral surface of said sleeve to said cooling chamber for directing a spray of cooling medium outwardly through said bores onto the outer surface of the extrudate passing adjacent to said inner peripheral surface of said cooling sleeve.

5. An apparatus for controlling an extrudate as set forth in claim 4, wherein said apparatus has a cooling and sizing tank mounted adjacent to said sleeve, and sizing means mounted in said cooling tank to size and extrudate to the finished size.

6. An apparatus for controlling an extrudate comprising an extruder, a die member with an opening therein mounted on one end of said extruder for shaping said extrudate, an annular heat insulating disc abutting said die member around said opening, a cooling sleeve abuttingly contacting said disc and having an aperture therethrough, said aperture being in alignment with said opening of said die member of said extruder, said aperture being larger in diameter than the diameter of said opening, said cooling sleeve having an annular cooling chamber, said sleeve having an inlet and an outlet opening communicating with said cooling chamber for circulating coolant therethrough to cool said cooling sleeve, said cooling sleeve having a plurality of spraying bores closely adjacent to said insulating disc communicating said cooling chamber with an inner peripheral surface of said sleeve, said bores having a porous sintered metal throughout the length thereof to facilitate the movement of cooling fluid from said chamber through said bores for directing a fine spray coolant to the clearance space between said inner peripheral surface and the extrudate for contact with the external surface of the extrudate passing through said sleeve.