US3911705A

US3911705A - Extrusion apparatus

Info

Publication number: US3911705A
Application number: US456684A
Authority: US
Inventors: William G Voorhes
Original assignee: WANSKUCK Co
Current assignee: WANSKUCK Co
Priority date: 1974-04-01
Filing date: 1974-04-01
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

An extrusion apparatus comprising at least a first and second member forming a passageway, a die being held in position by an abutment closing the end of the passageway and a band means located against one wall of the passageway so as to form an antifriction device.

Description

United States Patent 1 1 1111 3,911,705

Voorhes Oct. 14 1975 [5 EXTRUSION APPARATUS 3,349,153 10/1967 Beck 72/351 3,740,985 6/1973 Fuchs, Jr. [75] Inventor: fi; gi East 3,765,216 10/1973 Green 72/262 reenwic [73] Assignee: Wanskuck Company, Providence, FOREIGN PATENTS OR APPLICATIONS Rl 487,791 12/1953 Italy 72/286 [22] Filed: 1974 Primary Examiner-Victor A. DIPalma [21] Appl. No.: 456,684 Attorney, Agent, or Firm-Bar1ow & Barlow [52] US. Cl. 72/45; 72/92; 72/184; [57] ABSTRACT Int Cl 2 2532 An extrusion apparatus comprising at least a first and i Second member forming a passageway a die being [58] Field of Search 1688; held in position y an abutment Closing the end of the passageway and a band means located against one wall of the passageway so as to form an anti-friction de- [56] References Cited vice.

UNITED STATES PATENTS 2,602,538 7/1952 Bimba et a1 72 43 8 Clam, 6 Drawmg Flgures US. Patent Oct. 14, 1975' Sheet 2 of2 3,911,705

/7II 5 A 5 Y F l G 4 y Ex riusioN' APPARATUS BACKGROUND or THE INVENTION Extrusion broadly is the, process in which a piece of solid material is converted into a continuous length of uniform cross section by forcing the material to flow under high pressure through a die orifice which is so shaped as to impart the required form to the product. Until relatively recently the main form of extruding material in this general pattern has been to do it as a hot operation, the material being heated to a suitable degree of softness and plasticity to permit it to be forced through the orifice. More recently hydrostatic extrusion has come into our technology as represented by the Fuchs U.S. Pat. No. 3,740,985 and a different approach has been described in ASME paper No. 73- WA/PT-2 and the Green U.S. Pat. No. 3,765,216. In the Green patent, a feed grip is utilized between a wheel and a shoe and the material is progressively squeezed into a groove of the wheel against a die orifice. In processing material using the Green patent, heat is generated within the feed stock because of the sliding contact with the shoe member. It is apparent that excessive temperatures may be achieved such as to anneal the material being extruded and turn out an inferior product. It is therefore an object of the present invention to control the amount of heat that is developed in this type of continuous extrusion apparatus and to reduce the power requirement.

SUMMARY OF THE INVENTION The present invention provides an improvement in the material extrusion process in which the metal is forced through a die means by frictional engagement of the metal in a groove or passageway that is located within a wheel or block, the material being retained in the groove by a shoe member that is held stationary with respect to the wheel. In particular the improvement utilizes a band member that is located between the shoe and the walls of the groove and is held against the shoe by the feedstock. In this preferred embodiment the band member is continuous. The band is normally moved by frictional engagement between the feedstock and the band. In some cases the band is restrained from such free movement. The degree of movement of the band with respect to the feedstock controls essentially the temperature rise in the feedstock due to friction.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a detached perspective view of the main parts of the extrusion apparatus made in accordance with this invention;

FIG. 2 is a part sectional longitudinal elevational view of a modified form of extrusion apparatus made in accordance with the teachings of this invention;

FIG. 3 is a partial sectional view showing a detail of a modified form of shoe that is part diagrammatic indicating the source of fluid being fed thereto by a pump;

FIG. 4 is a partial sectional elevational view of a modified form of the invention;

FIG. 5.isa sectional view taken on lines 55 of FIG FIG. 6 is a detached perspective view of the elemental form of the extrusion apparatus of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The extrusion apparatus comprises a wheel 10 which is rotatably mounted on a shaft 12 that is suitably driven by a source of power (not shown) The wheel has a circumference 14 containing a passageway or groove 16, the groove taking a variety of forms of shape depending upon the type of feedstock being extruded. Fitting closely within the groove 16 of the wheel is a shoe member 18 which is suitably anchored in position relative to the axis of rotation of the shaft 12 and this shoe member has an arcuate mating edge 20 which substantially conforms to the curvature of the bottom wall of the groove. An abutment member is suitably anchored in position relative to the axis of rotation of the shaft 12 and has a projecting portion 26 with a nose 27 that is shaped to fit within a groove 16 of the wheel 10. On the end of the nose 27 is a die insert 28 which has an orifice 29 therein ofa shape of the product to be extruded and the projecting portion 26 and 27 together with the anchor means in the form of a block 30 are formed with a thru bore 31 so that the material extruded through the orifice 29 may pass through the abutment block 30. Against the arcuate surface 20 of the shoe 18 is a band 35 which effectively closes the groove 16 so as to provide the closure wall thereof and this band 35 passes between the side walls 17 of the groove 16 of the wheel 10 and bears against the arcuate surface 20 of the shoe 18. Band 35 may be made continuous as shown in which case it is fed around

guide pulleys

37, 38, 39. Since the band forms the closure for the groove 16 it will be apparent that the material M as seen in FIG. 2 will bear against this band and create a frictional drag thereon normally moving the band in the direction of rotation of the wheel 10 as seen by the arrow A. It is desirable that the band be provided with some lubricant on the surface thereof that faces the arcuate surface 20 of the shoe 18 and this lubricant can take the form of a number of greases such as the sodium series of greases or the EP greases.

Reference should now be made to FIG. 3 where a modified form of shoe 18 is disclosed, this shoe having a recess in its arcuate surface 20' which recess is designated 40. The recess comprises a central longitudinal groove of a length substantially the length of the contacting surface 20 which communicates with a number of bores 42 that lead to a pump 43 that is connected to a source of fluid such as air or oil. In effect fluid which is fed under pressure to the groove provides a bearing for the band 35, such fluid being used as a lubricant so as to maintain the band 35 and the arcuate surface of shoe out of direct contact by developing a film of fluid under compression underneath the band 35. In effect, the film of fluid operates in the same fashion that a hydrostatic bearing operates, the fluid escaping out under the edge of the band 35 whre the same is guided between the side walls of the groove.

It is also desirable in some cases to control the temperature of the stock that is being extruded. If the speed of the band 35 is the same as the speed of the feedstock, then there will be substantially no friction forces to increase the temperature of the stock being extruded. On the other hand if it is desired to raise the temperature of the stock being extruded, then the speed of the band 35 may be varied with respect to the feedstock and to this end a caterpillar drive generally designated 50 may be provided, the caterpillar drive being made similar to the caterpillar drives used widely in wire handling field and may be made substantially in accordance with US. Pat. No. 2,776,832. It will be understood that a separate drive means for the caterpillar may be provided or a variable speed coupling provided to the main shaft 12.

Referring now to FIGS. 4 and 5, there is shown a modification of the invention in which there will be less distortion of round feedstock than in the squaregrooved version represented in FIGS. 1-3. The wheel "is provided with a groove 16" which is of substantially circular section with the center radius thereof as at r positioned radially inward of the circumferential surface of the wheel 10 so as to yield for a partial distance side walls 17" that are tangent to the circle cross section. The shoe 18" has a groove 50 therein which complements the circular cross section of the groove 16" of the wheel so as to provide a grip thereon, the feedstock yielding and upsetting to fill the cross section. The band 35" that is utilized between the feedstock and the show 18" is such that it will conform to the shape of the groove 50 due to its inherent flexibility and will reduce the friction of the feedstock by virtually eliminating the frictional drag on the shoe. In all other respects this modification is similar to that previously described in connection with FIG. 1.

Refer now to FIG. 6. Essentially the use of a wheel is a practical form of a continuous process device which in its elemental form comprises a block 10A having a groove or passageway 16A, an abutment A and shoe 18A upon which band A rests. Stated in other terms, the passageway 16A may be defined by the walls of a pair of first members 62, 63, a second shoe member 18A and a third plate member 60. Such a device is useful for discontinuous extrusions and it will immediately be apparent that the first and third members are coupled together for movement while the second member and the abutment are stationary.

It will be understood that this apparatus operates substantially in the same manner as that disclosed in US Pat. No. 3,765,216. The difference between the operation of the instant device and the Green patent lies in the fact that the feedstock does not press directly against the arcuate surface 20 of the shoe member 18 but against the band 35 that bears against the arcuate surface 20 of the shoe member and the groove 16. The material M is carried toward the die member 28 by frictional drag of the side walls 17 and the bottom wall of groove 16. It will be apparent that there are frictional forces set up on each of the four contacting sides of the material M. Three of the sides are aiding motion of the material and only one is resisting, that is the side which now contains the band 35. It is this fourth side of the member in the Green patent which creates considerable friction and resulting power loss and gives rise to a significant temperature increase in the feedstock. Additionally, by eliminating the fourth side drag, various groove configurations are possible. As explained by Green in his US. Pat. No. 3,765,216 and the article in Journal of the Institute of Metals 1972, Vol. 100, p. 295, the compressive stress on the feedstock does not exceed the yield strength of the feedstock where the feedstock enters the passageway. However, the compressive stress on the feedstock in the die region will exceed the yield strength of the feedstock, causing the feedstock to yield and upset P ZY ara 3 Since the force to overcome friction along length I can be expressed where p. is the coefficient of friction between the feedstock and the shoe therefore P Fnu'Tlox Pun 2 3 The total force required both to extrude and to overcome shoe friction can be expressed:

TOTAL EXTRL'SIOA FRICTION If the groove/shoe cross section is square, then FTOTAL =PW PW (P/Y 2) u/S I claim:

1. Extrusion apparatus comprising a passageway formed between two opposing walls in a first member, the bottom of the passageway being closed by a surface of a second member, said surface having lubricant thereon, the top of the passageway being closed by a third member, an abutment extending into the passageway and closing an end thereof, a die insert positioned against the abutment, a continuous band being guided for movement on the lubricated surface of the second member about the apparatus, the surface wall area of the first member being greater than the surface area of the band lying against the third member, means for feeding material to be extruded to said passageway, said material bearing against said band and moving the same toward said abutment.

2. Extrusion apparatus comprising first and second members forming a passageway therein, said first member providing means forming a groove, said second member closing the groove, by means defining a surface, lubricant on said surface, an abutment at one end of the passageway, a die insert held by the abutment, and a continuous band being guided by the first member about the apparatus and bearing on a lubricated surface of the second member facing the passageway, means for feeding material to be extruded to said passageway, said material bearing against said band and moving the same toward said abutment.

3. Extrusion apparatus as in claim 2 wherein said first member is a wheel and the second member is a shoe facing the bottom wall of the groove.

4. Extrusion apparatus as in claim 2 wherein the arcuate surface of the shoe member is concave in cross section.

5. Extrusion apparatus comprising first and second members forming a passageway, said first member being a wheel with a groove therein, said groove having side and bottom walls, the second member having a surface closing the groove of the first member, an abutment extending into the passageway and closing an end thereof, a die insert positioned against the abutment and a continuous band being guided for movement on the lubricated surface of the second member about the apparatus, the surface wall area of the first member being greater than the surface area of the band lying against the third member, means for feeding material to be extruded to said passageway, said material bearing against said band and moving the same toward said abutment.

6. Extrusion apparatus as in claim 5 wherein said first member is a wheel and the second member is a shoe tween the band and the support means therefor.

I l l l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 911, 705

Dated October 14. 1975 Inventor-(s) William G. VOOIheS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the specification line 21 of column 4, please correct the formula to read as follows:

F '=Pw -+2 A FRiCTlON Y 3 Signed and Sealed this Arrest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner ofParents and Trademarks

Claims

6. Extrusion apparatus as in claim 5 wherein said first member is a wheel and the second member is a shoe facing the bottom wall of the groove.

7. Extrusion apparatus as in claim 5 wherein the arcuate surface of the shoe member is concave in cross section.

8. A process of extruding material comprising feeding solid stock material into a passageway formed between a band and a groove in another member, moving the other member, providing die means closing one end of said passageway, providing means to support the band , moving the band at the input feed speed of the solid stock and providing continuous lubrication between the band and the support means therefor.