Method and apparatus for drawing round stock with evaporative cooling

Abstract

An apparatus and method for drawing round stock to produce tubing includes a drawing machine including a drawing die, as well as an evaporative cooling mechanism adjacent to the drawing machine. The evaporative cooling mechanism defines a passageway in axial alignment with tubing drawn in a straight drawing direction and includes a nozzle for producing a fine fluid for cooling the tubing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser. No. 09,747,611 filed on Dec. 22, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to a method and apparatus for drawing round stock to produce tubing and, more particularly, to a method and apparatus for cooling the drawn tubing between successive stages of drawing.

BACKGROUND OF THE INVENTION

[0003] When drawing tubes to reduce the tube diameter and tube wall thickness, the tubes rapidly increase in temperature as they are forced through the die and about the mandrel. The increase in temperature causes the tubes to become brittle, often resulting in broken tubes. The problem becomes more serious as a larger diameter reduction is necessary because the stock tubing must be forced through a series of dies, each of which increases the temperature of the tubing. The loss of stock tubing and the production of low quality tubing is a significant disadvantage of the conventional manufacturing process.

SUMMARY OF THE INVENTION

[0004] The method and apparatus according to the invention draws round stock to reduce the tube diameter and the tube wall thickness through a series of dies with evaporative cooling between each successive die. More particularly, a series of drawing machines are adjacently arranged in line such that round stock is successively drawn to form increasingly smaller tubing through each machine. Cooling between each machine is provided in an evaporative cooling mechanism connected to a source of fluid and having spray nozzles for applying a mist of fluid to the tubing as it moves from one drawing machine to the next. Through this process and apparatus, the drawn tubing is appropriately cooled to prevent breaking of the tubing as it is successively drawn.

[0005] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0007] FIG. 1 illustrates schematically an arrangement of drawing machines with interposed cooling mechanisms;

[0008] FIG. 2 is a flow diagram of the process according to the invention;

[0009] FIG. 3 is a perspective view of an evaporative cooling mechanism according to the invention;

[0010] FIG. 4 is an end view of the evaporative cooling mechanism of FIG. 3; and

[0011] FIG. 5 is a cross-sectional view of a nozzle assembly used in the evaporative cooling mechanism of FIG. 3 and schematically illustrates communication with a source of cooling fluid.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0013] FIG. 1 illustrates an apparatus 10 for drawing stock tubing with interposed cooling stages according to the invention. As shown, evaporative cooling is provided between adjacent drawing machines, whereby drawn tubing 12 is cooled between successive drawing stages. While three drawing machines 20, 22, 24 are shown, more or fewer drawing stages may be employed as required to narrow the diameter of the drawn round stock and thin the tubular walls thereof. Between each drawing machine is an evaporative cooling mechanism 26, as shown. More or fewer evaporative cooling mechanisms 26 can be provided as needed for the drawing machines.

[0014] The drawing machines can be any conventional drawing apparatus for drawing stock tubing to reduce the tubular diameter and wall thickness thereof through a plurality of drawing stages. Preferably, the drawing machines are those sold by Firma Schumag AG of Aachen, Federal Republic of Germany, such as that described in U.S. Pat. No. 4,962,658, which is herein incorporated by reference.

[0015] The method according to the invention is illustrated in FIG. 2. At 50, the process of drawing round stock with evaporative cooling begins. At 52, stock tubing is provided for drawing into tubing have a narrower diameter and thinner walls. At 54, the stock tubing is drawn through a first drawing machine. Before proceeding to the next drawing machine at 58, the drawn tubing is cooled at 56 by an evaporative cooling mechanism. At 60, if there are additional drawing machines for further reducing the drawn tubing's diameter, the process moves to 62, where the drawn tubing is cooled by another evaporative cooling mechanism before returning to step 58, where the once-drawn tubing is drawn through the next drawing machine to further reduce the diameter thereof. After the last drawing stage is completed, the process ends at 64.

[0016] The evaporative cooling mechanism 26 is illustrated in FIGS. 3 and 4. As shown, the evaporative cooling mechanism 26 generally includes a box-like housing 30 with a rectangularly cross-sectioned tubing passageway therethrough, and four nozzle assemblies 34. More or fewer nozzle assemblies can be provided as needed. The housing 30 preferably includes six sides, including two generally rectangular sides 32 disposed adjacent each other, a pair of shorter generally square sides 36 separated from each other by the passageway, and two generally opposed sides 38 having a generally rectangular opening therein to provide an ingress and egress for tubing 12 traversing the passageway. Each side 32, 36, 38 of housing 30 includes a slot 70 for adjustably receiving a nozzle assembly 34. Further, each nozzle assembly 34 is connected to a supply source of fluid. The fluid is preferably water.

[0017] As the tubing 12 passes from one drawing machine to the next, it is cooled by the evaporative cooling mechanism 26. More specifically, the tubing 12 passes through the passageway of evaporative cooling mechanism 26 where it receives a mist of water or other fluid from the nozzle assemblies 34. The nozzle assemblies 34 are particularly adapted to apply a fine mist of water or other fluid, whereby the heat from the drawn tubing 12 rapidly evaporates the fluid. This rapid evaporation provides the necessary cooling between drawing stages, and provides clean, dry tubing 12 for the subsequent drawing machine.

[0018] Each nozzle assembly 34 includes a base plate 72 and a nozzle 74. Each base plate 72 and nozzle 74 are slidably received in the slot 70 of the sides 32,36 to adjustably mount the nozzle assembly 34 to the housing 30 for appropriate evaporative cooling of the tubing 12. Fasteners 76 are provided to secure the nozzle assembly 34 in place once properly adjusted in each slot 60.

[0019] As shown in FIG. 5, each nozzle assembly 34 includes a cylindrical body 40, a passageway 42 through the body 40, and an inlet 44 and outlet 46 for the passageway 42. At the inlet 44, the nozzle 64 is connected to a source 41 of water or other fluid by an adaptor 45. The passageway 42 contains a velocity tube 43 that receives the water or other fluid at the inlet 44 and transports it through the nozzle passageway 42. The velocity tube 43 connects at the outlet 46 of the nozzle 64 to a chamber 47. The diameter of the chamber 47 narrows toward the outlet 46 to such an extent that the fluid pressure is increased.

[0020] A spray tip 48 is preferably connected to the chamber 47 by a push lock 49, as shown in FIG. 5, or by some other known method of retention. The spray tip 48 releases the water in the form of a fine mist at the outlet 46. The narrowly directed mist is aimed at the drawn tubing 12 passing through the evaporative cooling mechanism 26.

[0021] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A system for drawing round stock to produce tubing with a reduced tube diameter and tube wall thickness, comprising:

a drawing machine including a drawing die; and

an evaporative cooling mechanism adjacent to said drawing machine, said evaporative cooling mechanism defining a passageway in axial alignment with said drawing die to accommodate the tubing in a straight drawing direction, and a nozzle operable to produce a fine fluid mist for cooling the tubing from said drawing machine.

2. The system according to claim 1 wherein said evaporative cooling mechanism includes a housing defining said passageway therethrough to accommodate said tubing from said drawing machine.

3. The system according to claim 2 wherein said nozzle is mounted to said housing.

4. The system according to claim 3 wherein said nozzle includes a body, a passage through said body, an inlet and an outlet for said passage, and a spray tip connected to said body at said outlet to direct said fine fluid mist toward said tubing.

5. The system according to claim 4 further comprising a source supplying cooling fluid to said inlet to said passage, which communicates said fluid to said outlet.

6. The system according to claim 4 wherein said passage includes a chamber for pressurizing said cooling fluid.

7. The system according to claim 2 wherein said nozzle is adjustably mounted to said housing.

8. An evaporative cooling apparatus for cooling drawn round stock from a drawing die, said apparatus comprising:

a housing having a passageway therethrough to accommodate traversing drawn round stock in a straight drawing direction from the drawing die;

a plurality of nozzle assemblies adjustably mounted to said housing;

a source supplying cooling fluid to said plurality of nozzle assemblies; and

a spray tip connected to each of said plurality of nozzle assemblies to direct said cooling fluid toward the drawn round stock.

9. The evaporative cooling apparatus according to claim 8 wherein said passage includes a chamber for pressurizing the cooling fluid.

10. The evaporative cooling apparatus according to claim 8 wherein each said nozzle assembly includes a body, a passage through said body, and an inlet and an outlet for said passage.

11. A method for cooling drawn round stock, comprising: providing round stock;

drawing said round stock through a first drawing machine to produce drawn tubing; and

cooling said drawn tubing in an evaporative cooling mechanism.