US3191833A - Tube break-off apparatus - Google Patents

Description

J 1955 F. H. WALKER E TAL 3, ,833

TUBE BREAK-OFF APPARATUS 2 Sheets-Sheet 1 Filed May 21, 1964 INVENTORS FRANK H. WALKER; KENNETH E.M -W\LL\AMS &3'o$EPl-\ D. MASE BY THa A TORMEY June 29, 1965 F. H. WALKER ETAL 3,191,833

TUBE BREAK-OFF mums Filed May 21, 1964 2 sheets-sheet 2 PIC-5.6 F-'\G.7 4

r 38 INVENTORS.

J FRANK HJA/ALKER; 39 KENNETH E. M wlLUAMS THEFR ATTORNEY 3,191,833 TUBE BREAK-GEE APPARATUS Frank H. Walker, Kenneth E. McWiiliams, and Joseph I). Wise, Louisville, Ky., assignors to General Electric Company, a corporation of New York Filed May 21, 1964, Ser. No. 369,133 2 Elairns. (Cl. 225102) The present invention relates to apparatus for breaking tubing and is particularly concerned with apparatus for providing a clean, burr-free break in small diameter tub ing such as that generally known as capillary tubing.

Small diameter copper tubing is used extensively in the refrigeration industry for restricting refrigerant flow and thereby maintaining a pressure differential between the condenser and the evaporator components of a rerigera-tion system. The flow restriction provided by any given capillary tube is dependent both upon its internal or bore diameter and its length. Generally, tubing in the capillary tube range has a maximum external diameter in the neighborhood of about 0.125 inch and a maximum internal diameter of about 0.065 inch. In the production of such small diameter tubes, a tube of relatively large diameter, for example one inch diameter, manufactured by an extrusion process is subjected to a plurality of drawing steps until its inside and outside diameters have been reduced to the desired points. In one method of drawing copper tubing, the initial reductions are carried out by use of fixed drawing dies for reducing the external diameter of the tube and floating plugs having a tapered end portions which ride within the tube adjacent the entry to the drawing die for obtaining the desired internal diameter of the tube in each drawing step. Both the interior and exterior surfaces of the tube are lubricated with a suitable lubricant during each drawing operation. Since capillary tubing as used in the industry must be cleaned and as it is dificult to pass a cleaning fluid through long lengths of small diameter tubing, it is the usual practice to wash the tubing free of lubricant at about the stage where it has been reduced to about one-fourth inch outer diameter and to perform the remaining reductions without use of the floating plug. After the tubing has been drawn to final capillary tube size, it has been cut to length and again carefully washed and flushed to remove any burrs or other foreign material resulting from the cutting operation. The second washing operation markedly increases the per pound cost of tubing having an outside diameter substantially less than one-fourth of an inch.

A specific object of the invention is to provide apparatus by means of which capillary tubing can be severed substantially to length using any low cost separating or cutting means and the roughly severed ends thereafter sheared or broken off to form clean burr-free breaks.

Additional objects and features of the invention will become obvious from the following specification taken in conjunction with the accompanying drawings and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In the drawings:

FIGURE 1 is a plan View of one embodiment of the present invention illustrating one step in the operation thereof;

FIGURE 2 is a view similar to FIGURE 1 showing a 3,ll,8 33 Fatented June 29, 1965 second step in the operation of the apparatus of FIG- UREl;

FIGURE 3 is a sectional view of the apparatus of FIGURE 1 taken generally along line 33 of FIG- URE 2;

FIGURE 4 is a view taken generally along line 44 of FIGURE 1;

FIGURE 5 is a view taken along line 5-5 of FIG URE 4;

FIGURE 6 is a sectional view along line 6--6 of FIGURE 3;

FIGURE 7 is a sectional view of the ends of the tubing as broken off by the apparatus of the present invention; and

FIGURE 8 is a somewhat schematic View of a second embodiment of the present invention in the form of a manually operated apparatus.

With particular reference to FIGURES 1 to 3 of the drawings, there is illustrated one embodiment of the present invention comprising a tube clamping means 1 suitably secured to a base 2 and including a fixed member 3 and a movable member 4- operated by a hydraulic pisotn generally indicated by the numeral 5. The members 3 and 4 each support clamping jaws 6 and 7 respectively including cooperating channels 8 and 9 adapted to receive and securely clamp a length of small diameter tubing 10 adjacent one end thereof. The movable member 4 has supported thereon a gauge arm 11 which includes a depending portion 12 positioned in front of the channel section 8 when the clamping means is open as illustrated in FIGURE 1 of the drawing in order to facilitate the positioning of the tube 10 in the clamping means with the forward end 14 of the tube extending a predetermined distance in front of the face portion 15 of the clamping means.

For the purpose of shearing the projecting end portion 14 of the clamped tube 10 and provide a clean burr-free end on the remainder of the tube, means are provided for bending the end portion 14 at a slight angle with regards to the axis of the main portion of the tube It and rotating this end portion along a conical path about the axis of the clamped portion of the tube 10. This orbital movement of the end of the tube relative to the clamp portion has been found to break the tube and provide a clean surface completely free of burrs or the like.

To provide the desired conical motion of the tube end 14, there is provided a member 16 which is adapted to be rotated by a motor 17, the motor 17 in turn being supported on the base 2 by means such as a hydraulic cylinder (not shown) whereby the member 16 can be reciprocated between a retracted position as illustrated in FIGURE 2 and an operating position as illustrated in FIGURE 3. More specifically, the movable member is is in the form of a rod journalled in a bearing 18 supported on the base 2.

The member 16 is supported with its center axis, that is its axis of rotation, coaxial with the longitudinal axis of the tube 10 as supported in the clamping means 1. The forward end of the member 16, that is the end 20 facing the clamp face 15, has an arcuate portion thereof cut away to form a sloping surface portion 22 adapted to engage and bend the end 14 of the tube when the member 16 is advanced to the position as shown in FIG- URE 2. The member 16 also includes a second surface 24 extending substantially at right angles to the J: surface 22 and offset from the center line 19 of the member 16 approximately equal to half of the exterior diameter of the tube 10.

In the operation of this embodiment of the invention, the tubing 10 is inserted into the clamping means as shown in FIGURE 1 of the drawing until the forward end of the tube engages the portion 12 of the gauge arm. The hydraulic cylinder is then operated to close the jaws 3 and 4 so that the tube becomes firmly or rigidly clamped within the channel sections 8 and 9, the portions of these channels at the face 15 ofthe clamping means preferably engaging the outer surface of the tube about its entire periphery.

Movement of the clamping member 4 causes the gauge arm to move laterally away from the end 14- of the tube to the position shown in FIGURE 2 of the drawing. The member 16 is then advanced from its retracted position to its forward or advanced position and during this movement, the sloping surface 22 engages the tube end 14 causing this end to bend slightly relative to the clamped portion of the tube about a point adjacent the face 15 of the clamping member. The member 16 is designed to advance, to a point which is relatively close to but nevertheless spaced from the face 15 and for the usual tube of the capillary tube range of sizes, the distance between the face 15 and the end 20 of the member 16 may be of the order of about one-eighth of an inch when the member 16 is in its advanced position. If desired, the forward edge of the surface 24 may be beveled as indicated by the numeral 27 to assure that the tube end 14 will pass into the arcuate relieved area during advance of the member 16.

When the movable member 16 is in its advanced position, one surface of the tube 14 is in engagement with the sloping surface 22 while a second surface at about a 90 angle from this first surface is in engagement with the surface 24.

The number 16 is then rotated in a direction such that the surface 24 causes the tube end 14 to rotate in a conical path about the axis of the clamped portion of the tube thereby subjecting the portion of the tube immediately adjacent the face 15 to circumferentially progressing tension and compression forces which quickly cause work hardening of this portion of the tube whereby the end 14 of the tube shears or breaks free from the clamped portion.

The movement of the end 14 during this break-off operation is illustrated in FIGURE 6 of the drawing. It will be noted that counterclockwise rotation of the member 16 as viewed in FIGURE 6 causes the extreme tip of the tube end 14 to follow an annular path as indicated by the broken line 30. This movement rotates the angle of the bend of the tube at the face 15 around the wall of the tube thereby subjecting each portion of the tube wall to alternate tension and compression. After a few turns, the end 14 shears along a shear plane as illustrated in FIGURE 7 of the drawing. The slope of the surface 22 which determines the angle to which the tube end 14 is bent relative to the clamp portion can vary but ordinarily will not exceed an angle in the neighborhood of about The minimum angle is that which will subject the break-off portion of the tube to sufiicient work hardening stresses so as to obtain a clean break within a reasonable length of time.

It has been found that best results are obtained when the slope of the surface 22 is such that the shear surface 31 is in the form of a concave shear line or plane on the clamped tube which, as is indicated in FIGURE 7 of the drawing, .is at an angle of about 45 with reference to the tube axis. Specifically it has been found that when such a shear line or plane is obtained, the end portion 14 of the tube is broken away from the main portion of the tube without the formation of any burrs on either the inner or outer surfaces of the tube and with no significant change in the internal diameter of the tube. The preferred slope for the surface 22 to obtain this result depends upon the diameter of the tubing. For most tubing within the capillary tube range, that is tubing having an external diameter of one-eighth inch or less, it has been found that satisfactory results are obtained when the tip of the tube is offset from the clamp portion of the tube about one-half of the diameter of the tube. In general, for

tubing having an external diameter from 0.080 to 0.125

inch, offset angles between 5 and 15, and preferably between 6 and 9, have been found to provide the desired 45 shear plane.

In FIGURE 8 of the drawing there is illustrated a manually operated apparatus for accomplishing the purposes of the present invention. That apparatus which is particularly adapted for field use comprises a clamping member including a fixed jaw 33 and a movable jaw 34 operated by a cam 35 having an operating handle 36. The tubing 10 is clamped between the jaws 33 and 34 with the end 14 extending forwardly from the face of the clamp. A rotatable member 37 journalled in a support 39 is adapted to be rotated by an arm 40. The member 37 has a slot 38 therein the lower or bottom surface of which is provided with a slope of the same order as the slope of the surface portion 22 of the apparatus previously described. The shaft 41 is adapted to slide within the support 39 so that the member 3'7 can be advanced to a point where the end 14 of the tube enters the slot 38 where it is slightly offset or bent. Manual rotation of the member 37 causes the tube end 14 to move along the same circular path as that illustrated in FIGURE 6 of the drawing thereby work hardening the tube end to provide the desired break.

While the invention has been described with specific reference to certain embodiments thereof it will be understood that it is not limited thereto and it is intended by the appended claims to cover all such modifications as come within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Tube break-off apparatus comprising:

clamping means for clamping a portion of a tube with one end of said tube extending beyond a face of said clamping means,

a movable member supported for reciprocal move ment relative to said clamping means along a line parallel to the axis of the clamped tube portion between a first position and a second position adjacent to but spaced from said face,

said movable member including a first surface adapted upon movement of said movable member to its second position to offset said tube end at an angle of from about 5 to 15 relative to said clamped portion,

said movable member including a second surface substantially normal to said first surface for engaging said ofi'settube end,

, and means for rotating said movable member about the axis of the clamped portion of said tube in a direction such that said second surface engages said tube end for rotation thereof about the axis of said clamped portion for separating said end from said tube.

2. Tube break-off apparatus comprising:

clamping means for clamping a portion of a tube with i one end of said tube extending beyond a face of said clamping means, 7

a movable member supported for reciprocal movement relative to said clamping means along a line parallel to the axis of the clamped tube portion between a first position and a second position adjacent to but spaced from said face,

said movable member including a first surface adapted upon movement of said movable member to its second position to offset said tube end at an angle of from about 6 to 9,

said movable member including a second surface sub- 3,191,833 5 6 stantially normal to said first surface for engaging References Cited by the Examiner sdald ofisetfmbe f M b b t UNITED STATES PATENTS an means or ro a ng sai mova e mem er a ou the axis of the clamped portion of said tube whereby 332; 225-102 X said second surface causes said tube end to travel 5 31383O8 6/64 Oakley 225-102 XR through a conical path to progressively subject the tube wall to tension and compression forces causing ANDREW JUHASZ, Pr'mary Examine"- work hardening and shearing of said wall. WILLIAM W. DYER, Examiner.

Claims (1)

1. TUBE BREAK-OFF APPARATUS COMPRISING: CLAMPING MEANS FOR CLAMPING A PORTION OF A TUBE WITH ONE END OF SAID TUBE EXTENDING BEYOND A FACE OF SAID CLAMPING MEANS, A MOVABLE MEMBER SUPPORTED FOR RECIPROCAL MOVEMENT RELATIVE TO SAID CLAMPING MEANS ALONG A LINE PARALLEL TO THE AXIS OF THE CLAMPED TUBE PORTION BETWEEN A FIRST POSITION AND A SECOND POSITION ADJACENT TO BUT SPACED FROM SAID FACE, SAID MOVABLE MEMBER INCLUDING A FIRST SURFACE ADAPTED UPON MOVEMENT OF SAID MOVABLE MEMBER TO ITS SECOND POSITION TO OFFSET SAID TUBE END AT AN ANGLE OF FROM ABOUT 5 TO 15* RELATIVE TO SAID CLAMPED PORTION, SAID MOVABLE MEMBER INCLUDING A SECOND SURFACE SURFACE SUBSTANTIALLY NORMAL TO SAID FIRST SURFACE FOR ENGAGING SAID OFFSET TUBE END,

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