US3379042A

US3379042A - Method and machine for form rolling

Info

Publication number: US3379042A
Application number: US516348A
Authority: US
Inventors: Sr Harry W Brown
Original assignee: National Acme Co
Current assignee: Devlieg Bullard Inc
Priority date: 1965-12-27
Filing date: 1965-12-27
Publication date: 1968-04-23
Anticipated expiration: 1985-04-23

Description

April 1968 H. w. BROWN, SR 3,379,042

METHOD AND MACHINE FOR FORM ROLLING Filed Dec. 27, 1965 5 Sheets-Sheet l illil; INVEA/ TOR.

1i 5 HARRY 14/. BROWN'S/2 F76. 2 BY P 1963 H. w. BROWN, SR 3,379,042

METHOD AND MACHINE FOR FORM ROLLING Filed Dec. 27, 1965 5 Sheets-Sheet 2 April was H. w. BROWN, SR 3,379,042

METHOD AND MACHINE FOR FORM ROLLING Filed Dec. 27, 1965 5 Sheets-Sheet Y FIG /2 //V VE N TOR HA RR Y W. BROWN, 57?.

BY m 20% April 23, 1968 H. w. BROWN, SR 3,379,042

METHOD AND MACHINE FOR FORM ROLLING Filed Dec. 27, 1965 5 Sheets-Sheet 4 5 Sheets-Sheet 5 H. W. BROWN, SR

April 23, 1968 METHOD AND MACHINE FOR FORM ROLLING Filed Dec. 2?, 1965 m 1 a m MM R @(k n MHHHHQ MM 0% ||l .h. W 7 w w m W $N i W MN W N n a w M F km 1 .3 M fi a F v m W mm. ww w; h 1- 11 H.H.H T. W n j r m a E. k

United States Patent 3,379,042 METHOD AND MACHINE 180R FORM RQLLHNG Harry W. Brown, Sn, Euclid, Ohio, assignor to The National Acme Company, a corporation of (lhio Filed Dec. 27, 1965, Ser. No. 516,348 18 Claims. (Cl. 72-10) The invention relates in general to the method and a machine for rolling a form on a workpiece and more par ticularly to a method and a machine for rolling a form such as a deep thread or an annular or helical fin on the exterior surface of a tube.

Tube finning machines have been made in the past to create a fin on a tube, for example, for heat exchangers to increase the effective surface area on the exterior of the tube. This is an example of one form of thread rolling or roll forming wherein the material of the workpiece is considerably extruded or cold formed by a considerable displacement of the metal or material of the workpiece. Other examples could include rolling square threads or deep threads on a workpiece. In such cases the rolls which engage the exterior surface of the tube are under considerable radial pressure. To cause the appreciable cold flow of the workpiece where a deep helical fin is desired on the workpiece or tube, the forming rolls must be machined to a complementary shape and thus will also have a long thin fin. In the past considerable difiiculty has been found in machining such form rolls and one solution has been to use stacked discs, each with sharpenededgcs, as the forming roll. However regardless of how the forming roll is constructed, whether in one piece or in several stacked discs, the long narrow tapering edge on the composite roll has been subject to considerable breakage. This breakage has been considered a necessary evil where such a deep fin was desired and this was one reason for using the stacked discs so as to aid replacement of a disc which had broken. However, even this caused considerable down-time of the machine while the rolls were being repaired or replaced.

The breakage of the prior art forming rolls has now been discovered to be caused by the subjecting of the rolls to other than purely radial forces. For example, a longitudinal force on the roll relative to the tube or workpiece can easily break off the edge of the long tapering fin on the roll. Also a rotational force on the roll relative to the roll head or relative to the tube can in turn cause a longitudinal force which again will break the fin on the form roll. Still further it has been found with deep penetration of form rolls into the exterior surface of a tube to cold form a deep fin on the tube, that an internal mandrel was necessary to prevent collapse of the tube. In the prior art this mandrel was in many cases stationary and with a longitudinally moving tube this created considerable friction again introducing a longitudinal strain on the form rolls to break off the fin. Further this longitudinal friction developed considerable heat and the heat further elongated the tube thus making it dilficult to establish a controlled length of the tube and the pitch or lead of the helical fin. The deep penetration and cold flow of the metal also resulted in considerable elongation of the tube in the exit and of the forming rolls. The longitudinal elongation frequently tended to move the mandrel in a forward direction and where the mandrel was held against this movement this caused longitudinal forces tending to break the fins on the forming rolls.

Accordingly, an object of the present invention is to obviate the above-mentioned disadvantages.

Another object of the invention is to provide a form rolling machine to roll deep threads, fins or forms on a workpiece or tube without any longitudinal forces on the forming rolls to substantially eliminate breakage of these forming rolls.

Another object of the invention is to provide servomotor powered movement of the relative longitudinal movement of the roll head and workpiece to eliminate longitudinal forces on the forming rolls.

Another object of the invention is to provide a machine wherein a controlled feed rate of relative movement of the tube and roll head is provided in order to establish movement for unformed land portions on the tube yet with this motor acting as a servomotor under control of a servovalve or control element for the form rolling of the tube. Further a follow-up movement is provided between the servovalve and the housing thereof in accordance with the movement of the motor.

Another object of the invention is to provide a means whereby a mandrel may be moved longitudinally within the tube to be exterioriy formed and to maintain the mandrel in position to prevent collapse of the tube despite the fact that the mandrel is frictionally urged in one direction by the action of the form rolling.

The invention may be incorporated in a form rolling machine, comprising, in combination, a frame, a carriage movable longitudinally on said frame, a motor connected to drive said carriage longitudinally of said frame, a form roll head including a plurality of form rolling rolls thereon, means to relatively longitudinally move said roll head and a tube to be form rolled in accordance with longitudinal movement of said carriage, means to establish a controlled feed rate of said motor for a forward longitudinal movement of the carriage, means to relatively rotate said roll head and the tube to roll a form on the exterior surface of the tube, a control element and housing, the relative rotation of said roll head and tube while in engagement relatively longitudinally moving the tube and the head, means to relatively move said control element and housing in accordance with the relative longitudinal movement of said roll head and the tube, means connecting said control element and housing to said motor for control of same to establish forward movement of said carriage, and means connecting said control element and housing for relative followup movement in accordance with longitudinal movement of said carriage.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view through a form rolling head which may be used in the invention;

FIGURE 2 is an end view of the form rolling head;

FIGURE 3 is an enlarged view of a forming roll and the tube being formed;

FIGURE 4 is a view of the completed workpiece of tube with the helical fin thereon;

FIGURES 5 through 16 are plan views, diagrammatical in many details, illustrating the sequence of operation for rolling a fin on a tube;

FIGURE 17 is a longitudinal elevational view, partly in section of the carriage portion of the machine of FIG- URE 5; and

FIGURE 18 is an end view of the carriage portion of the machine shown in FIGURE 17.

The form rolling method may be performed by a machine 20 illustrated as rolling a helical form on the exterior surface of a workpiece. The machine 20 is illustrated as rolling a deep helical fin on a workpiece or tube 21. This tube 21 is illustrated in FIGURE 4 and showing the helical fin 22. The machine 20 includes a frame 25 having a first end at the right and a second end at the left. A carriage 26 is disposed generally at the right end of the frame 25 and is slidably journalled for longitudinal movement on a way 27. The carriage 26 has mounted thereon a motor 29 shown as a hydraulic rotary motor. This motor 29 drives a pinion 3t engaging rack 31 fixed on the rear of the frame 25. Accordingly rotation of the pinion 30 moves the carriage 26 longitudinally of the frame 25. A servovalve 33 has a housing 34 containing a servovalve spool 35. This valve spool may be considered a control element. The servovalve housing 34 is fixed on the carriage 26 and has fluid conduits interconnecting with the hydraulic motor 29, as diagrammatically illustrated in FIGURE 10.

The machine also includes a plurality of rollers 37 mounted on cantilever arms 28 from the frame so as to avoid interference with the carriage 26. These rollers 37 support the tube 21 to be form rolled along the longitudinal axis 39 of the machine 20.

Mounted in a central area of the frame 25 is a support 40 for a form rolling head 41. The support 40 journals the roll head 41 for rotation around the longitudinal axis 39 and this head is better shown in FIGURES l and 2. The head 41 is adapted to be rotated around the axis 39 by any suitable means such as the motor 42. This motor 42 may rotate at a constant speed to establish a constant rate of forming the fin 22 on the tube 21.

FIGURES l and 2 better show the construction of the form rolling head 41 as including a rotatable housing 45 rotatable by the motor 42. Blocks 46 carry axles 47 on each of which a forming roll 48 is freely journalled. Four such forming rolls may be used and in FIGURE 2 only two such rolls are illustrated in order to show other parts of the mechanism. Each block 46 is slidable radially in the housing 45 and is urged outwardly by a spring 49 and by work pressure. Each forming roll 48 cooperates with the others to roll a helical fin or thread on the tube 21. In order to accomplish this the axis of the axles 47 may be parallel to the longitudinal axis 39, together with having a helical form on the forming rolls 48. Alternatively, a helical form on the rolls together with axes of the rolls skewed an amount corresponding to the helix will roll an annular groove on the workpiece and also longitudinally move the workpiece relative to the roll head. Alternatively as illustrated in this case, the forming rolls 48 may be provided with annular grooves thereon and may be simply constructed by a plurality of stacked discs 50. Where annular grooves are used on the forming rolls 48, then the axes of the axles 47 are skewed an appropriate amount corresponding to the helix desired to be formed on the workpiece.

A cup 52 surrounds the rotatable housing 45 and has a plurality of rollers 53, each one to engage a different block 46. Each block has a cam surface 54 so that upon longitudinal retraction of the cup 52 the springs 49 and the work rolling pressure will move the blocks 46 outward ly to open the head. In this condition the forming rolls 48 will not engage the tube 21. When the cup 52 is moved forwardly to the position shown in FIGURE 1 the rollers 53 move the blocks 46 inwardly to the closed position of the head. This closed position establishes the rollers for full depth penetration of the form of these rolls into the tube 21. A spool 55 is fastened to the rear of the cup 52. A yoke 56 engages this spool 55. Power means such as a fluid motor 57 is connected to actuate the yoke 56 to open and close the head 41. The fluid motor 57 is controlled by suitable means, shown diagrammatically in FIGURE 1 A mandrel 60 is diagrammatically shown in the FIG- URES 516. This mandrel has the left end thereof carried in a mandrel support 61. This support 61 may move longitudinally of the frame 25. A motive means 62, shown as a fluid cylinder in FIGURE 6 has a piston 64 connected by means of a cable 63 to the mandrel support 61. Movement of the piston 64 within the motive means cylinder 62 will move the mandrel support 61 longitudinally of the fram6e 25, between the positions shown in FIGURES 5 and A tube length sensing device 66 includes a support 67 longitudinally slidable on the frame 25. The device 66 further includes a tubular part 68 extending toward the roll head support 40. The free end 69 of the tubular part 68 is adapted to engage the forward end or second end 72 of the tube 21, as illustrated in FIGURE 7 compared to FIGURE 6. The first end 71 of the tube 21 is adapted to be clamped in a fixture 73 on the carriage 26, see FIGURES 5 and 17. The tubular part 68 thus surrounds the mandrel 60 and is of a diameter to engage the second end 72 of the tube 21. Adjustable pilot valves 74 are carried on the frame 25 and engaged by a cam 75 carried on the tube length sensing support 67. These valves 74 may be also limit switches, for example, and are connected to control the opening and closing of the roll head 41 by connection means 72 as diagrammatically illustrated in FIGURES 7 and 10. The roll head 41 is diagrammatically illustrated in FIGURES 5-16 in order to simplify these figures. For example, these valves may be limit switches to control energization of solenoids moving a fluid valve for selective control of fluid to the fluid motor power means 57, shown in FIGURE 1. Briefly when the cam 75 is in engagement with one of the limit switches or valves 74, as shown in FIGURES 5, 6, and 7, then the roll head is open. When the cam 75 is not in engagement with one of the valves or switches 74, for example as shown in FIGURE 8, then the roll head 41 is closed.

FIGURE 17 illustrates the carriage 26. The clamping fixture 73 may be clamped by a screw 78 to clamp the first end or right end 71 of the tube 21 to a plate 79. This plate is journalled for longitudinal sliding movements on a rod 80 fixed on the carriage 26. Linear bearings 81 may be provided for low fricton free floating movement of the plate 79, within limits. The plate 79 fixedly carries a bracket 82 into which a micrometer adjustment 83 is screwed and which is in alignment with the valve spool 35. A tension spring 84 urges the plate 79 to the right as viewed in FIGURE 17 and an internal spring 85 in the servovalve housing 34 urges the valve spool 35 to the left, see FIGURE 10.

FIGURE 10 illustrates diagrammatically the hydraulic circuit used for control of the fluid motor 29. This motor controls movement of the carriage 26 and accordingly the relative longitudinal movement of the tube 21 and roll head 41.

A pump 87 is illustrated in FIGURE 10 as a source of fluid pressure. A directional valve 88 is illustrated as a four-way valve with a neutral position. This valve 88 may be controlled by forward and reverse

control devices

89 and 90. These may be solenoids, for example. These forward and reverse

control devices

89 and 90 are connected by means 91 for control by a handle 92 which may be mounted for convenient use on the machine 20. In FIG- URE 10 this handle 92 is shown in the forward position and thus the valve 88 is shown in the forward position wherein fluid pressure is directed into a conduit 93 and a conduit 94 is connected to drain 95. Pressure in conduit 93 causes the fluid motor 29 to rotate in a forward direction causing forward movement of the carriage 26. This moves the tube forwardly, that is from the first end toward the second end thereof, and toward the roll head 41. A check valve 97 in the conduit 94 diverts fluid flow through the servovalve 33 for this forward movement. The servovalve 33 has been diagrammatically illustrated in FIG- URE 10 as being a restrictor valve variably restricting the flow of fluid therethrough. Flow is also through another check valve 98 and a branch conduit 99. Mechanical means shown as the micrometer adjustment 83 acts on the servovalve 33 to partially bias open this servovalve 33. This establishes a controlled feed rate of forward movement of the carriage 26. Viewing FIGURES 10 and 17, the spring 85 pushes the valve spool 35 to the left tending to open this valve. This tendency to open the valve is resisted by the tension spring 84. The micrometer adjustment 83 may thus be changed to vary the controlled feed rate of the carriage 26.

OPERATION A tube 21 to be roll formed may have the first end 71 thereof clamped in the clamping fixture 73 as illustrated in FIGURES 5 and 17. This tube 21 will be supported on the rollers 37 concentric with the longitudinal axis 39 of the machine 20. A valve 101 supplied by pressure fluid from a pump 102 may next be moved to move the piston 64 to the left to move the mandrel support 61 to the right. This moves the mandrel 60 inside the full length of the tube 21. The rear end or first end of this mandrel 60 may thus engage a stop 103 on the clamping fixture '73 on the carriage 26. This movement of the mandrel support 61 also moves the tube length sensing device 66 to the right near the roll head 41. This will be as shown in FIGURE 6. The motor 42 may then be actuated to rotate the roll head 41, for example, at a predetermined constant rate. The handle 92 may then be moved to the forward position as illustrated in FIGURE 7. This actuates the hydraulic system to move the valve 88 to the forward position, as shown in FIGURE 10. Pump pressure through conduit 93 actuates the fluid motor 29 in the forward direction. This motor 29 drives the carriage 26 to the left, or in the forward direction. The rate of movement will be at a controlled feed rate dependent upon the micrometer adjustment 83 which controls the opening of the servovalve 33. This could also be effected by a separate valve in parallel with the servovalve 33 but for simplicity, the two functions may be combined in the servovalve 33. This will move the tube 21 to the left, with the forward end 72 thereof engaging the free end 69 of the tube length sensing device 66, at the point shown in FIGURE 7.

The controlled feed rate of the motor 29 and carriage will continue to move the tube to the left from the position shown in FIGURE 7, overcoming the lesser force of the fluid motor motive means 62, which may be an air cylinder. When the cam 75 rides off the first limit switch 74, then the roll head 41 will close to begin to form a helical thread or fin on the tube 21. This will be as viewed in FIGURE 8 and there may be an unfinned land 105 at the forward end of the tube 21. This would help utilization of the tube 21 in a heat exchanger or other end product.

The closing of the rotating head 41 on the non-rotating tube 21 will cause a longitudinal movement of the tube through the roll head 41. This is because of the threading action of the fin formed on the tube and the longitudinal component of the lead or pitch of the helical thread or fin on the roll or on the workpiece. This component will establish longitudinal movement of the tube because of the rotation of the head 41 but at a different rate from the conrolled feed rate. Preferably the rate of pulling the tube through the head is at a faster rate than the controlled feed rate. Accordingly the tube 21 pulls on the clamping fixture 73. This in turn moves the plate 79 forwardly, see FIGURE 17 and the internal spring 85 moves the valve spool 35 forwardly to increase the fluid flow and increase the rate of movement of the fluid motor 29. This increases the rate of the carriage 26 to a second rate so that the fluid motor 29 acts as a servomotor under control of the servovalve 33. The carriage 26 is accordingly moved at the same rate of speed as the tube 21 in its passage though the roll head 41. The fact that the servovalve housing 34 is fixed on the carriage 26 is a means connecting the con trol element 35 and housing 34 for relative follow-up movement in accordance with the longitudinal movement of the carriage. This longitudinal movement of the carriage is that which provides relative longitudinal movement between the tube 21 and roll head 41. The motor 42 rotating the head 41 is that which provides relative rotational movement between the head 41 and tube 21 and thus establishes the rate of relative longitudinal movement between the tube 21 and head 41.

FIGURE 9 illustrates a position of further progress of the tube 21 through the head 41. The cam 75 has engaged a second one of the limit switches 74 to open the roll head 41. FIGURES l0 and 11 show that this cam has remained in engagement with the limit switch 74 for a length suflicicntly to establish an unthreaded or unfinned land 1106 on the tube 21. Such an unfinned land 106 may be used to provide a smooth exterior land portion on the tube 21 for support of the tube when assembled in the end product such as a heat exchanger. FIGURE 12 again shows the roll head 41 opened by the cam engaging another limit switch 74. FIGURE 13' shows this cam 75 about to ride of? this limit swich 74 and thus another land 106 will be formed as shown in FIGURES l3 and 14.

The form rolling action on the tube 21 elongates the finned portion of the tube 21. This is because of the considerable extrusion or cold flow of the metal or material forming the tube in order to form the very deep fins 22. For example, this tube may be A" in outside diameter and about .050" wall thickness. The complete helical fin 22 may be in the order of .080" deep with a remaining tube wall thickness 108 of about .020" to .030". This shows that the machine of the invention will produce a fin of considerably greater radial depth than the remaining radial thickness of the tube wall. This is a considerable deformation of the material of the tube wall. This cold flow of the material has been found to elongate the finned section of the tube 21 about 25 percent. This elongation takes place principally at the exit end of the forming rolls 48, which is at the bottom of FIGURE 3. The mandrel 60 fits the inner diameter of the tube 21 with only a slight clearance 109. As the rolls 48 act radially inwardly on the tube 21, the inner tube wall 110 is supported by the mandrel 60 to prevent collapse of this tube 21. As the finned tube exits from the forming rolls 48 there is a slight amount of resilient spring back of the tube 21 to provide a small clearance 111 between the mandrel 60 and the tube 21.

FIGURE 8 illustrates the fact that the mandrel 60, even though resiliently urged to the right by the motive means 62, has been frictionally moved to the left by the action of the roll head 41 elongating the tube. The longitudinal elongation of the tube 21 has been toward the finned end of the tube 21. This frictionally moves the mandrel 60 in the same direction and therefore the rearward end of this mandrel 60 has moved away from the stop 103 on the carriage 26. This is illustrated in FIG- URE 8. When the roll head 41 opens, as illustrated in FIGURE 9, or when the radial inward pressure of the rolls 48 on the tube 21, and hence the tube 21 on the mandrel 60 is slightly relieved, then the motive means 62 moves the mandrel 60 back to the right into engagement with the stop 103. This is as illustrated in FIGURE 9. The mandrel is moved away from the stop 103 during each of the form rolling actions as illustrated in FIG- URES 8, l1, and 14. Each time that the head 41 is opened, the mandrel 60 moves back to the right as illustrated in FIGURES 9, 12, and 15.

The fact that the motive means 62 is resilient in its urging toward the right in FIGURES 5l6, permits the mandrel 60 to be moved forwardly with the elongation of the finned portion of the tube. This avoids the longitudinal sliding friction between the mandrel and the tube which otherwise would occur if the mandrel was held stationary. This was a difficulty in prior fin rolling machines and such longitudinal sliding friction created considerable heat which further aggravated the strain on the finning or forming rolls. The present machine eliminates this source of friction and such longitudinal strain on the rolls. Accordingly there is no longitudinal force on the fins or the firming rolls relative to the tube and accordingly breaking of these rolls is greatly reduced. Also with the elimination of the heat of friction the tube is not elongated for this reason, and accordingly exact length of finned sections may be established. This establishes an exact number of fins per inch of tube length which is necessary to meet specifications for these finned tubes. In prior art machines which had a non-rotating head and gear driven rolls to rotate the rolls and the workpiece,

the elongation of the tube during the rolling action destroyed the preciseness of the number of rolled fins per inch of length. Also in such prior machines the threading action of the rolls onto the tube was that which longitudinally fed the tube through the head. This was a considerable longitudinal force applied on the slender fins of the forming rolls and this caused considerable breakage of these rolls. In the present machine, the motor 29, acting as a servomotor, supplies all of the force for the longitudinal movement of the tube to eliminate such 10ngitudinal forces on the slender fins of the forming rolls.

FIGURE 16 illustrates the return to the left of the mandrel support 61, caused by reversal of the valve 101. Also the handle 92 is now moved to the right to the reverse position, and this moves valve 88 to the right. This establishes full fluid flow into conduit 94 and the fiuid motor 29 runs freely in the reverse direction. This returns the carriage 26 to the right to the position shown in FIG- URE 16. The clamping fixture 73 may now be released and the completed finned tube may be removed from the machine 20. The machine is now ready for another cycle of operation.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts and steps may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A form rolling machine, comprising in combination,

a frame,

a carriage movable longitudinally on said frame,

a motor connected to drive said carriage longitudinally of said frame,

a form roll head including a plurality of form rolling rolls thereon,

means to relatively longitudinally move said roll head and a tube to be form rolled in accordance with longitudinal movement of said carriage,

means to establish a controlled feed rate of said motor for a forward longitudinal movement of the carriage, means to relatively rotate said roll head and the tube to roll a form on the exterior surface of the tube,

a control element and housing,

the relative rotation of said roll head and tube while in engagement relatively longitudinally moving the tube and the head,

means to relatively move said control element and housing in accordance with relative longitudinal movement of said roll head and the tube,

means connecting said control element and housing to said motor for control of same to establish forward movement of said carriage, and

means connecting said control element and housing for relative followup movement in accordance with longitudinal movement of said carriage.

2. A machine as defined in claim 1 including,

means to journal said form rolling rolls on said head for free rotation thereon.

3. A machine as defined in claim 1 including,

means to longitudinally move the tube by one end from the carriage and commencing the form rolling operation on the other end of the tube.

4. A machine as defined in claim 1 including,

means to rotate the roll head and to hold the tube rotatively stationary to have the form rolls rotate in engagement with the tube.

5. A machine as defined in claim 1 wherein said controlled feed rate is at a different rate of movement than that longitudinal movement established by the relative rotation of the roll head and tube while in engagement,

and said control of said motor by said control element and housing relieving the form rolls from any axial force relative to the roll head.

6. A machine as defined in claim 1 including,

a hydraulic servomotor as said carriage motor,

a servovalve having a valve spool in a housing as said control element and housing,

means to mount said servovalve housing on the carriage,

and means to control movement of said servovalve spool in accordance with movement of the tube relative to said carriage.

7. A machine as defined in claim 1, including,

a mandrel,

motive means to relatively move said mandrel longitudinally inside the tube to prevent collapse of the tube during rolling of the form thereon,

the tube elongating during the form rolling action and frictionally urging said mandrel to move longitudinally relative to one end of the tube,

said roll head being openable at least partially to relieve inward pressure between the tube and said mandrel,

and said motive means returning said mandrel into position inside the portion of the tube within the roll head during the period of relief of said inward pressure.

8. A machine as defined in claim 1, including,

said roll head being openable and being closable to engage a tube for rolling a form thereon,

means to open said roll head to establish an unformed land on the tube,

and said controlled feed rate of said motor continuing the forward movement of said carriage to produce said unformed land.

9. A machine as defined in claim 8, including,

a mandrel,

and said motive means returning said mandrel into position inside the portion of the tube within the roll head during the period of establishing said unformed land.

10. A machine to roll a deep thread on a tube having first and second ends comprising, in combination,

means to non-relatively hold the first end of the tube,

means to move said tube longitudinally from said first end toward said second end,

a thread rolling head having thread forming rolls freely rotatably journalled in said head,

means to open said head to have the rolls spaced sufficiently to not contact the tube and means to close the head to have the rolls form a deep thread in the tube,

power means to longitudinally forwardly move the tube toward the second end,

means to close the head and to rotate the head to roll a helical thread on the exterior of the tube,

the thread rolling action moving the tube longitudinally through the head, and

means responsive to the thread rolling action producing longitudinal movement of the tube to control said power means as a servomotor to feed the tube forwardly from the first end to the second end thereof to relieve longitudinal forces on the thread forming rolls.

11. A machine as defined in claim 10, including,

means to sense the length of the rolled thread end of the tube,

means responsive to said length sensing means to open the head to form an unthreaded land on the tube,

and said power means feeding the tube forwardly during the unthreaded land portion of the tube passage through the head.

12. A machine as defined in claim 11, including,

a mandrel of a length exceeding the length of the tube to be rolled and having first and second ends,

and motive means to move the mandrel first end longitudinally into the full length of the tube from the second end to the first end.

13. A machine as defined in claim 12, including,

the thread rolling action on the tube longitudinally elongating the tube and frictionally moving the mandrel forwardly so that the first end thereof moves away from the first end of the tube,

and said motive means moving the mandrel rearwardly during movement of the tube for the unthreaded land portion of the tube to have the first end of the mandrel moved adjacent the first end of the tube.

14. A thread rolling machine, comprising in combination,

a frame having first and second ends,

a carriage movable longitudinally on said frame,

a hydraulic motor connected to drive said carriage longitudinally of said frame,

a hydraulic servovalve having a housing and a valve spool,

means to move said servovalve housing with movement of said carriage,

means to connect a tube to be threaded to said valve spool to move same, a mandrel longitudinally movable relative to said frame, a thread rolling head including a plurality of thread rolling rolls journalled for free rotation thereon, motive means to move said mandrel longitudinally inside of the tube to be threaded into engagement with said carriage,

said rolling head being openable and being closable to engage a tube for rolling threads thereon,

means to establish a controlled feed rate of said hydraulic motor for a forward longitudinal movement of the carriage and tube,

means to rotate said roll head,

means to close said roll head to roll a thread on the exterior surface of the tube with the tube held against rotational movement and with the mandrel preventing collapse of the tube during rolling of the thread,

the rotation of said rolling head threading itself onto the tube and pulling the tube longitudinally to move said servovalve spool in said forward longitudinal direction,

means connecting said servovalve to said hydraulic motor for control of same to establish forward movement of said carriage under control of said servovalve,

a tube length sensing device adjacent said mandrel and disposed near said second end of said frame,

said tube length sensing device contacting the forward end of the tube during forward longitudinal movement thereof to be moved forwardly therewith,

means cooperating with said tube length sensing device to open said roll head to establish an unthreaded land on the tube,

said controlled feed rate of said hydraulic motor continuing the movement of said carriage to produce said unthreaded land,

the tube elongating during the thread rolling action and causing said mandrel to move longitudinally away from said carriage,

and said motive means returning said mandrel into engagement with said carriage during the period of establishing said unthreaded land.

15. The method of using a roll head having rolls to roll a helical form on a tube, comprising the steps of,

relatively longitudinally forwardly moving the tube and the roll head by power means at a first rate,

relatively rotating the tube and roll head and causing the rolls thereon to engage the exterior surface of the tube with the relative rotation of the head and tube causing relative longitudinal movement therebetween at a second rate in accordance with the rotational speed and pitch of the helical form,

said second rate being different from said first rate,

and controlling the rate of movement of said power means in accordance with said second rate.

16. The method as set forth in claim 15, including,

journalling the rolls for free rotation on the roll head.

17. The method as set forth in claim 15, including,

holding the tube non-rotatively and rotating the roll head,

and holding the head non-longitudinally movable and moving the tube longitudinally through the roll head.

18. The method as set forth in claim 15, including,

inserting a mandrel in the tube,

measuring the length of the externally formed portion of the tube,

controlling the opening of the head in accordance with said measured length to establish an unformed land on the tube,

the form rolling action elongating the tube and thus causing the mandrel to frictionaily move longitudinally with the portion of the tube being form rolled,

and moving the mandrel during the roll head open conditions which established the unformed lands to maintain the mandrel in a position inside the tube at the roll head.

References Cited UNITED STATES PATENTS 1,860,989 5/1932 Brinkman 72-96 1,982,369 11/1934 Brinkman 72 96 2,092,873 9/1937 Brinkman 72-118 2,157,598 5/1939 Fentress et al 72ll2 2,669,278 2/1954 Andersen 72--118 2,714,919 8/1955 Johnston 7296 2,757,706 8/1956 Johnston 72-96 3,137,926 6/1964 Barlow et a1. 72-367 3,203,256 9/1965 Lehnert 72-77 3,262,295 7/ 1966 Wolosynek 7225 CHARLES W. LANHAM, Primary Examiner.

E. M. COMES, Assistant Examiner.

Claims

1. A FORM ROLLING MACHINE, COMPRISING IN COMBINATION, A FRAME, A CARRIAGE MOVABLE LONGITUDINALLY ON SAID FRAME, A MOTOR CONNECTED TO DRIVE SAID CARRIAGE LONGITUDINALLY OF SAID FRAME, A FORM ROLL HEAD INCLUDING A PLURALITY OF FORM ROLLING ROLLS THEREON, MEANS TO RELATIVELY LONGITUDINALLY MOVE SAID ROLL HEAD AND A TUBE TO BE FORM ROLLED IN ACCORDANCE WITH LONGITUDINAL MOVEMENT OF SAID CARRIAGE, MEANS TO ESTABLISH A CONTROLLED FEED RATE OF SAID MOTOR FOR A FORWARD LONGITUDINAL MOVEMENT OF THE CARRIAGE, MEANS TO RELATIVELY ROTATE SAID ROLL HEAD AND THE TUBE TO ROLL A FORM ON THE EXTERIOR SURFACE OF THE TUBE, A CONTROL ELEMENT AND HOUSING, THE RELATIVE ROTATION OF SAID ROLL HEAD AND TUBE WHILE IN ENGAGEMENT RELATIVELY LONGITUDINALLY MOVING THE TUBE AND THE HEAD, MEANS TO RELATIVELY MOVE SAID CONTROL ELEMENT AND HOUSING IN ACCORDANCE WITH RELATIVE LONGITUDINAL MOVEMENT OF SAID ROLL HEAD AND THE TUBE, MEANS CONNECTING SAID CONTROL ELEMENT AND HOUSING TO SAID MOTOR FOR CONTROL OF SAME TO ESTABLISH FORWARD MOVEMENT OF SAID CARRIAGE, AND MEANS CONNECTING SAID CONTROL ELEMENT AND HOUSING FOR RELATIVE FOLLOWUP MOVEMENT IN ACCORDANCE WITH LONGITUDINAL MOVEMENT OF SAID CARRIAGE.