US3635073A

US3635073A - Mechanical tube expander

Info

Publication number: US3635073A
Application number: US888785A
Authority: US
Inventors: Richard M Oliver
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1969-12-29
Filing date: 1969-12-29
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18
Also published as: NL7018878A; ES386890A1; SE398202B; CA919073A

Abstract

A mechanical tube expander including a cage having rollers mounted therein and a tapered mandrel to coact therewith for expanding the tube. A locking member permits movement of the mandrel a predetermined distance after the rollers make initial contact with the inner surface of the tube, thereby causing a predetermined expansion of the tube.

Description

ilnited Mates Patent @lliver [4 Jan. m, 1.972

[54] MECHANICAL TUBE EXPANDER [72] Inventor: Richard M. Oliver, Chattanooga, Tenn.

[73] Assignee: Combustion Engineering, line, Windsor,

Conn.

[22] Filed: Dec. 29, 1969 [21] Appl. No.: 888,785

[52] US. Cl. ..72/393, 72/120, 72/399 [5 1] int. Cl ..B21d 41/02 [58] Field of Search. ..72/393, 399, 400, 370, 77, 72/78, 113, 120; 29/523 [56] References Cited UNITED STATES PATENTS 2,736,950 3/1956 Mathews ..29/523 3,247,695 4/1966 Linthicum et al ..72/370 2,405,399 8/1946 Bugg et al ..29/523 2,737,996 3/1956 Toth 2,393,283 l/l946 Boyles et al ..29/523 Primary Examiner-Charles W. Lanham Assistant Examiner-Michael J Keenan Attorney-Carlton F. Bryant, Eldon H. Luther, Robert L. 01- son, John F. Carney, Richard H, Berneike, Edward L. Kochey, Jr. and Lawrence P. Kessler {57] ABSTRACT A mechanical tube expander including a cage having rollers mounted therein and a tapered mandrel to coact therewith for expanding the tube. A locking member permits movement of the mandrel a predetermined distance after the rollers make initial contact with the inner surface of the tube, thereby causing a predetermined expansion of the tube.

4 Claims, 3 Drawing Figures PATENTEU JAN 18 1972 N llullm 2 m NI W7. W M W H m R IIIIIA \9 M NN NN 0w 0 nah/d! Q 0 m 3 WEI ATTORNEY MECHANICAL TUBE EXPANDER BACKGROUND OF THE INVENTION Mechanical tube expanders have been used for some time to expand tubes into good physical contact with tube sheets. One problem that has always existed in tube expanders is in expanding the tubes sufficiently to obtain the desired contact between the tube and tube sheet, while preventing overexpansion which can damage thin wall tubes. This problem is particularly troublesome because of the inconsistencies in tube inner diameters.

SUMMARY OF THE INVENTION The tube expander of the present invention makes use of releaseable locking means and a spring having a given amount of compression, which members coact with a tapered mandrel and a collar means which abuts a tube end, for causing expansion of the tube a predetermined amount. Thus regardless of the original inner diameter of the tube, it is always expanded a predetermined amount, substantially alleviating the problem of overexpansion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section of a tube expander at the start of an expanding operation;

FIG. 2 is a cross section of the tool at the completion of an expanding operation; and

FIG. 3 is a sectional view of the gripping mechanism taken on line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now to FIG. 1, numeral denotes a mechanical tube expander having a tapered mandrel 12. Mandrel 12 extends through a cage which houses a plurality of rollers 16. As the mandrel moves longitudinally through the cage 14 from right to left as shown in FIG. 1, the increasing diameter of the mandrel moves the rollers radially outward, until they contact the inner surface of a tube 17 which is to be expanded into good physical contact with a tube sheet 19.

A collar 18 determines how far into the tube 17 the cage and its associated rollers extend. A thrust bearing 20 permits rotation of the cage 14 during the expanding operation, while permitting the collar 18 to remain stationary. Rotation of the collar 18 during the expanding operation could cause scarring of the tube end and tube sheet against which it abuts, and would be undesirable. The above-described structure is old, and operates in the same manner as other mechanical tube expanders presently being used. A suitable pneumatic, hydraulic, or electric motor (not shown) is attached to the right end 24 of mandrel 12 to cause rotation thereof.

The novel apparatus of the invention which causes a predetermined amount of expansion of the tube 17 will now be described. A quick release sleeve 26 surrounds the mandrel 12 rearwardly of the collar 18. This sleeve 26 has a tapered or conical inner surface which acts as a wedge. Integral with sleeve 26 is a hand ring 27. Positioned inside of sleeve 26 is a cylindrical member 28, which acts as a housing for a pair of locking or gripping lugs 30. Integral with housing 28 is a thumb ring 22. The lugs 30 extend through slots (see FIG. 3) cut through the housing 28 so that their grooved inner surfaces can engage and interlock with the grooves 32 on the surface of the mandrel 12 when they are moved inwardly by the tapered surface of sleeve 26. This locking position is shown in FIG. 2. Two pairs of

springs

34 and 35 bias the lugs 30 outwardly away from contact with the grooves 32 which is the position shown in FIG. 1.

A spring 36 biases the quick release sleeve 26 and thumb ring 22 apart. Positioned intermediate the collar 18 and cylindrical member 28 is a spacer spring 38. On the left end of spring 38 a spring seat 40 is located. Seat 40 has a cylindrical extension 41, the purpose of which will be later described.

LII

The operation of the tube expander will now be described. When it is desired to expand a tube, the operator inserts the cage 14 into the bore of the tube 17, until collar 18 contacts the tube and tube sheet. The operator then grasps the thumb ring 22 and hand ring 27, moving them together, causing compression of spring 36. Springs 34 and 35 thus cause the locking lugs to move outwardly away from the grooves 32 on the mandrel 12, as the release of the wedging action of the quick release sleeve 26 permits. Mandrel 12 is now free to be moved longitudinally of all of the members surrounding it, including the cage 14, collar 18, and cylindrical member 28. Mandrel 12 is then moved into the tube 17 until the tapered portion thereof causes the rollers 16 to be moved outwardly into contact with the inner surface of the tube.

The operator then moves the quick release sleeve 26 and housing 28 by means of their associated rings 27 and 22 to the left with respect to the mandrel, until spring seat 40 abuts against collar 18 and the right end of spring 38 just touches and abuts against cylindrical member 28. Spring 38 should be stiff enough so that it will not be compressed unless some degree of force is exerted. The operator then releases ring 27. Spring 36 thus causes ring 27 and its integral quick release sleeve 26 to move to the left. The wedging action on gripping lugs 30 causes them to move inwardly into a gripping or looking relationship with grooves 32. The tube expander is now ready to cause expansion of the tube 17.

The drive motor for the tool is actuated at this time, causing rotation of the mandrel, which in turn causes rotation of the rollers 16 and the roller cage 14. The rollers 16 to mandrel 12 axial relationship is skewed 1 to 3 degrees which is well known in the industry as a self-feeding expander. Rotation of the mandrel 12 causes said mandrel to feed inwardly to the left, the rollers 16 thereby being moved radially outward to expand the tube 17. Because of the positive wedging or locking action between lugs 30 and grooves 32 the cylindrical member 28 moves along with the mandrel 12. Continued rotation of the mandrel 12 causes continued longitudinal travel of the mandrel l2 and cylindrical member 28 which causes compression of spring 38. The longitudinal movement of the mandrel 12 and member 28 continues until the end of cylindrical member 28 makes contact with the end 41 of the spring seat 40. This condition of the tool is shown in FIG. 2. No further longitudinal movement of the mandrel is possible at this time.

From the above, it can be seen that the mandrel 12 can move only a predetermined longitudinal distance D" after the rollers 16 initially touch and make contact with the inner surface of tube 17. Since the mandrel has a fixed angle of taper throughout its tapered length portion, the rollers 16 will be cammed outwardly a fixed given amount due to the movement of the mandrel, causing the tube 17 to be expanded a predetermined amount.

Although in the preferred illustrated embodiment spring seat 40 with a cylindrical piece 41 is used as the stop member for abutting against the end of member 38 at the end of the expanding operation, this member could be eliminated. If this were done, the spring 38 would have to be fully compressed before longitudinal movement of the mandrel 12 were stopped. In this instance, the predetermined distance the mandrel would move during the expansion operation would be determined by the difference in length of spring 38 in its uncompressed and fully compressed state.

From the above, it can readily be seen that the tube expander of the present invention can be used by even a relatively inexperienced operator to cause a predetermined amount of tube expansion time after time. Tolerance is very good. For example, if the grooves 32 are 1/32-inch apart, and 1/16 inch of longitudinal travel of the mandrel causes a 0.00l-inch tube expansion by the rollers 16, the tolerance will be plus or minus 0.0005 inch of the desired expanded tube diameter. The predetermined amount of tube expansion can be readily and easily changed by using different sized spacer springs.

What is claimed is:

1 A tube expander including a tapered mandrel, a cage with radially movable rollers mounted therein surrounding the mandrel, which rollers move outwardly as the tapered mandrel moves longitudinally therethrough, collar means surrounding the mandrel rearwardly of the cage and adapted to abut against the end of the tube to be expanded, gripping means surrounding the mandrel rearwardly of the collar means, spring means positioned between the collar means and the gripping means and adapted to abut against the end of each, said gripping means having a first position which permits longitudinal movement of the mandrel with respect thereto, and a second position in gripping contact with the mandrel, so as to move longitudinally therewith, whereby when a tube is to be expanded the gripping means is originally maintained in its first position until the rollers contact the inner surface of the tube to be expanded and the spring in its uncompressed state is in contact at one end with the collar means and at its other end with the gripping means, at which time the gripping means is moved to its second position, and the gripping means along with the engaged mandrel are moved longitudinally with respect to the collar means a predetermined distance until the spring has been completely compressed, thereby causing a predetermined amount of expansion of the tube.

2. The tube expander set forth in claim 1, wherein the gripping means includes lug means which are spring biased away from the mandrel, and wedge means for forcing the lug means into engagement with the mandrel.

3. The tube expander set forth in claim 2, wherein the lug means has a grooved surface which engages the mandrel, and the mandrel has grooves which coact with those on the lug means.

4. The tube expander set forth in claim 3, including means biasing the wedge means towards the position which forces the lug means into engagement with the mandrel.

Claims

1. A tube expander including a tapered mandrel, a cage with radially movable rollers mounted therein surrounding the mandrel, which rollers move outwardly as the tapered mandrel moves longitudinally therethrough, collar means surrounding the mandrel rearwardly of the cage and adapted to abut against the end of the tube to be expanded, gripping means surrounding the mandrel rearwardly of the collar means, spring means positioned between the collar means and the gripping means and adapted to abut against the end of each, said gripping means having a first position which permits longitudinal movement of the mandrel with respect thereto, and a second position in gripping contact with the mandrel, so as to move longitudinally therewith, whereby when a tube is to be expanded the gripping means is originally maintained in its first position until the rollers contact the inner surface of the tube to be expanded and the spring in its uncompressed state is in contact at one end with the collar means and at its other end with the gripping means, at which time the gripping means is moved to its second position, and the gripping means along with the engaged mandrel are moved longitudinally with respect to the collar means a predetermined distance until the spring has been completely compressed, thereby causing a predetermined amount of expansion of the tube.