US3613982A

US3613982A - Friction welder

Info

Publication number: US3613982A
Application number: US799049A
Authority: US
Inventors: Dale W Hollenberg; Calvin D Loyd; Ronald L Satzler
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1969-02-13
Filing date: 1969-02-13
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19
Also published as: BE745520A; FR2035433A5; AU1111670A; GB1279181A; DE2006053A1; CA922943A

Abstract

A friction welding machine has a direct center drive means wherein the rotor of the drive means functions as the workpiece holding spindle for one or more center driven workpieces; the machine is adapted for use as a dual welder wherein a movable tailstock is employed on each side of the center drive means and also for use with a single tailstock on one side of the center drive and a supplemental thrust bearing means on the other side of the center drive. One embodiment of the machine incorporates a free-floating center drive means. A special workpiece holding device is also provided wherein a special adjustable toggle linkage arrangement is adapted to provide gripping means for a large number of variously sized workpieces.

Description

United States Patent [72] Inventors DaleW.Hollenberg Rolla, Mo.; Calvin D. Loyd, Peoria; Ronald L. Satzler, Metamora, Ill. [21] Appl. No. 799,049 [22] Filed Feb. 13, 1969 [45] Patented Oct. 19, 1971 [73] Assignee Caterpillar Tractor Co.

Peoria, Ill.

[5 4] FRICTION WELDER 16 Claims, 12 Drawing Figs.

[52] US. Cl 228/2, 29/4703, 156/73, 279/41 [51] Int. Cl B231: 27/00 [50] Field of Search 228/2;

[5 6] References Cited UNITED STATES PATENTS 3,417,457 12/1968 Burkeetal. 29/4703 Primary Examiner.lohn F. Campbell Assistant ExaminerRobert J. Craig AnorneyFryer, Tjensvold, Feix, Phillips & Lempio ABSTRACT: A friction welding machine has a direct center drive means wherein the rotor of the drive means functions as the workpiece holding spindle for one or more center driven workpieces; the machine is adapted for use as a dual welder wherein a movable tailstock is employed on each side of the center drive means and also for use with a single tailstock on one side of the center drive and a supplemental thrust bearing means on the other side of the center drive. One embodiment of the machine incorporates a free-floating center drive means. A special workpiece holding device is also provided wherein a special adjustable toggle linkage arrangement is adapted to provide gripping means for a large number of variously sized workpieces.

1 HYDRAULIC SOURCE AND CONTROLS ELECTRICAL POWER 5 SUPPLY AND CONTROL 1 HEAT EXCHANGER l6 UNIT PAIENTEuum 19 12m SHEET 2 OF 8 G ;R E OB TN m L mo H W E M D CALVIN D, LOYD RONALD L. SATZLER I I BY 9 ATTORNEYS PAIENTEDucI 19 ml 3. 5 1 3 9 8 2 SHEET 7 OF 8 INVENTO S DALE W. HOLLENB G CALVIN D. LOYD RONALD L. SATZLER BY 2 Z M wag W +55% AT PORN EYS SHEET8UF 8 PATENTEDucnsmn INVENTORY; DALE W. HOLLENBERG u M m 5 r .A D

D W v L v A0 9/ CR FRICTION WELDER BACKGROUND OF THE INVENTION This invention relates to improvements in friction welding apparatus of the general type wherein two workpieces are subjected to relative rotation while in contact with each other to generate frictional heat to raise the workpieces to a suitable welding temperature, whereupon the relative rotation subsides and a bond is formed between the workpieces.

It is also to be understood that the invention is specifically applicable to apparatus for performing the inertia welding process as described in US. Pat. No. 3,273,233 and as set forth below. In the inertia welding process the energy required to bring the common interface of the parts to a bondable condition is stored as kinetic energy in rotating inertia weights. These weights generally take the form of flywheels and are connected to one of the parts and the entire energy necessary to form the bond is stored in the weights prior to the engagement of the parts at the interface. The stored energy is discharged into the interface through frictional heating and plastic working developed at the interface as the rubbing contact slows the rotating weights and the bonding cycle is concluded.

More specifically, the present invention is directed to a friction welding machine having a direct center drive means wherein the rotor of the drive means functions as the workpiece holding spindle for one or more center driven workpieces. Use of the rotor shaft as the welder spindle offers important advantages over prior art structures in that it provides a drive system which eliminates the use of costly gearing arrangements, complicated belt drives and pulleys, etc. The elimination of such intermediate drive components also reduces lubrication requirements as well as maintenance problems associated with the relatively complex drive systems of prior art devices.

A further object and advantage of the invention resides in the employment of a center drive workpiece holding device which in one embodiment comprises a free-floating center drive and wherein either a single workpiece may be held in and protrude from either end of the center drive, or separate workpieces may protrude from either end of the center drive, and a tailstock assembly is provided on either side of the center drive means for holding separate workpieces against rotation and wherein the tailstock assemblies may be simultaneously actuated to move axially into engagement with the center drive means whereby axial thrust forces are balanced at the center drive means.

A further object and advantage of the friction welding device of the present invention resides in the employment of either a fixed direct center drive or a free-floating center drive means in combination with a movable tailstock on one side of the center drive and a supplemental thrust bearing means on the other side of the center drive.

Still another object and advantage of the invention resides in the provision of a workpiece holding device having an adjustable toggle linkage arrangement to permit clamping and accurate adjustment for various sizes of workpieces.

Other and further objects and advantages of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what are now considered to the be the best modes contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view illustrating one exemplary embodiment of a friction welding machine constructed in accordance with the present invention;

FIG. 2 is a top plan view of the friction welding machine shown in FIG. 1;

FIG. 3 is a cross-sectional view taken on the line III-III of FIG. l and illustrating certain details of the center drive means of the present invention;

FIG. 4 is a longitudinal view, partially in section, illustrating certain structural details of the center drive means of the present invention;

FIG. 5 is a cross'sectional view illustrating structural details of a novel workpiece holdingdevice of the present invention;

FIG. 6 is a top plan view of the workpiece holding device depicted in FIG. 5;

FIG. 7 is an end view of a friction welding machine constructed in accordance with the present invention;

FIG. 8 is a side elevational view illustrating a modified em bodiment of a friction welding machine constructed in accordance with the present invention and including a free-floating center drive means;

FIG. 9 is a cross-sectional view taken on the line IX-IX of FIG. 8 and illustrating certain details of the free-floating center drive embodiment of the present invention;

FIG. 10 is a side elevational view illustrating a modified embodiment of the friction welding machine shown in FIG. 8;

FIG. 11 is a longitudinal view, partially in section, illustrating certain structural details of a supplemental thrust bearing arrangement for use with the embodiment illustrated in FIG. 10; and

FIG. 12 is an end view of the supplemental thrust bearing arrangement illustrated in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT A friction welding machine constructed in accordance with one exemplary embodiment of the present invention is indicated generally by the reference numeral 10 in FIGS. 1 and 2. The welding machine 10 comprises a housing or frame 12 which houses suitable hydraulic controls 14 and electrical controls 16 for the operation of the machine as will be described at a later point in the description. A heat exchanger unit 17 is provided at one side of the frame to provide oil cooling for various parts of the machine in the event such cooling is found necessary or desirable. The top of the housing 12 is provided with a bed plate 18 for supporting various components of the welding machine.

Guide means, preferably in the form of a pair of spaced guide rods 20 are supported on the bed 18 by means of suitable mounting brackets 22. A hollow shaft, electrical induction, drive motor shown generally at 24 is fixedly supported upon the guide rods 20 by means of a gusset and stand assembly 25 which is secured at its lower end to the bed plate 18. As will be described in detail at a later point of the description a hollow rotor shaft of the motor 24 serves as the center drive spindle for rotating one or more workpieces to be welded such as shown at 26 and 28.

Two movable tailstocks shown generally at 30 and 32 are slidably supported upon the guide rods 20 on each side of center drive motor 24. A pair of double-acting hydraulic rams 34 are rigidly mounted to the end support brace 22 with their rod ends extending through the support for attachment to tailstock 30 as shown at 35. A similar pair of rams 36 are provided for movement of the tailstock assembly 32. While two rams are shown associated with each tailstock, it is to be understood that unitary ram means could be employed if desired. The

rams

34 and 36 are provided with a fluid pressure port 37 for the admission and emission of pressure fluid from the hydraulic controls to the head ends of the rams. A similar fluid pressure port 38 is provided for the rod ends of the rams.

As best shown in FIG. 3 the center drive motor is fixedly secured to the guide bars 20 by means of cantilever clamps 27. During a friction welding operation the tailstock assemblies 30 and 32 are simultaneously actuated by the

rams

34 and 36 to engage workpieces (not shown) held in the tailstocks with the rapidly rotating

workpieces

26 and 28 held in .the center drive 24.

Referring now to FIG 4 in conjunction with FIG. 3, it will be observed that the motor 24 comprises stator windings 46 which are embedded in slots provided in the stator core 48. Rotor bars 50 are shown embedded in the slots provided in the rotor core 52. The rotor and stator are separated by a radial airgap 54.

It should be noted that a spindle or rotor shaft 56 is provided with a hollow bore 58 through which a center driven workpiece or workpieces can be inserted to be clamped by

chucks

60 and 62 attached at either end of the rotor shaft 56. Since the core through the rotor shaft is coaxial with the chuck openings one long workpiece can be passed through the rotor to be clamped by both chucks or each of two shorter workpieces can be held in the individual chucks.

The rotor shaft is also provided at either end with flange elements 64. The flange elements 64 are provided with drilled holes or other suitable means for attaching the

chucking devices

60 and 62 and also one or more flywheels such as 66 which may be required to provide the proper amount of stored energy. Suitable bearing means 67 are provided for the shaft assembly 56.

The motor 24 is a Class K induction motor which is a low slip device. The Class K motor is characterized by low torques at speeds that are a low percentage of synchronous speed but develop maximum torque at about cycles of slip from synchronous speed regardless of the frequency applied to the motor. Maximum motor efiiciency (electrical) is at about one cycle slip. These characteristics used in a variable frequency system allow the advantage of a highly efficient system over a high-speed range.

The details of the tailstock assembly 30 will now be described with reference to FIGS. 5, 6 and 7. It should be understood that the description with respect-to the tailstock 30 applies equally to the tailstock 32. As best shown in FIGS. 5 and 6 a tailstock frame comprises two laterally spaced end plates 80 and 80' reinforced by a bottom plate 82 and two connecting metal straps 84 and 86. The end plates are further connected by tubular bushings 88 and the tailstock is slidably mounted on the guide rods through the employment of linear motion bearings 90.

First toggle links 92 and 92' are secured in the tailstock by through-bolts 94 and 94' as best shown in FIG. 6. The toggle links 92 and 92' extend the full length of the tailstock and have three projected connecting

arms

96, 98 and 100. A second set of

toggle links

101 and 102 are connected to the first set of toggle links by

pins

104 and 106 respectively. The second set of

toggle links

101 and 102 are provided with V-

blocks

108 and 110 which are attached to the ends of the

links

101 and 102 respectively, such as by countersunk capscrews.

The center arms 98 and 98' formed on the first toggle links 92 and 92' are pivotally connected by pins Ill and 111'to the upper ends of actuating

links

112 and 114. The lower ends of actuating

links

112 and 114 are connected by a common pivot pin 115 to the bifurcated end ofa rod 116. The rod 116 is provided with a piston 117 which is received in a cylinder 118. The cylinder 118 is mounted to the center of bottom plate 82 and the rod 116 extends upwardly through the bottom plate to the pivotal attachment 115 for the actuating links 112 and 114.

Actuation of the above-described double-toggle arrangement to cause clamping and unclamping of a workpiece is effected by vertical motion of the rod 116 inwardly and outwardly of the cylinder 118. Thus, when oil is introduced at a port 126 the rod 116 will be moved inwardly as shown and the V-

blocks

108 and 110 will be moved into a clamped position. Introducing pressure fluid at a port 128 will cause the rod 116 to be moved outwardly of the cylinder 118 and thereby move the V-

blocks

108 and 110 to an unclamped position.

The V-

blocks

108 and 110 are replaceable to permit the clamping of various sized workpieces. Further, an are traced by the

links

101 and 102 is adjustable to cause the V-

blocks

108 and 110 to engage the workpiece properly. Adjustment of the aforementioned arc is accomplished by follower elements, such as small rollers or pins 134 and 136 mounted on the

links

101 and 102, following a path defined by

arcuate guides

138 and 140.

The position of the

arcuate guides

138 and 140 is adjustable through positioning of rods 142 and 144 associated with each of the

guides

138 and 140. The rods 142 and 144 are welded to the

guides

138 and 140 and vertical adjustment of the guides is provided through adjustment nuts and 151 associated with the rod 142, and nuts 152 and 153 associated with the rod 144. Transverse adjustment of the

guides

138 and 140 is provided by

slots

154 and 155 formed in the metal straps 84 and 86 and slots 156 formed in the bottom plate 82.

Prior to clamping the workpiece in the V-

blocks

108 and 110, the workpiece is placed in a bracket 160 which holds the workpiece at the correct level prior to being clamped by the V-blocks. The brackets 160 are replaceable and can be changed with the V-blocks to permit welding of various sized parts.

The hydraulic control 14 of FIG. 1 consists of a fluid source, pressure pump, and other components to permit proper operation of the tailstock cylinders 118 and the thrust rams 34 and 36. The electrical controls 16 comprise proper circuitry to start and accelerate the motor 24 to a preselected speed, sense the motor speed, automatically shutoff power to the motor when a speed is proper and provide a signal to the hydraulic controls to initiate the welding sequence.

At the beginning of a welding operation either a single workpiece may be fed through the hollow shaft of the motor 24 and clamped in place by closing

chucks

60 and 62 or two separate workpieces may be clamped in the

chucks

60 and 62. Separate workpieces are then placed in each of the

tailstock assemblies

30 and 32 and the hydraulic controls 14 are actuated to cause tailstock cylinders 118 to lock the workpieces securely in the tailstocks.

The electrical controls are then set and actuated to cause the motor 24 to accelerate to a speed proper for welding of the materials being joined. When the desired speed is reached, a feedback speed signal causes the power to the motor to be discontinued and simultaneously a signal is sent to the hydraulic controls to supply pressure fluid to

rams

34 and 36 which causes the

tailstocks

30 and 32 to be urged toward the motor 24 until the workpieces held in the tailstocks come into contact with the rotating workpiece or workpieces held in the spindle of the motor 24.

During the welding operation the fixed motor 24 is in a balanced condition between the

tailstocks

30 and 32 since the thrust of the rams 34 cancels out the thrust of the rams 36. This balanced condition minimizes the load on the bearings of the motor 24. Upon completion of the weld, the controls function to operate the tailstock cylinders 118 to unclamp the workpieces and the

chucks

60 and 62 are loosened to permit the joined workpieces to be removed.

In the event that a single workpiece is fed through the hollow shaft of the motor 24 and welded to end pieces held in each of the

tailstock assemblies

30 and 32, the joined material may be fed through the welder until the free end of the part originally held in one of the tailstocks is located in the other tailstock. If desired a new splice section can then be inserted through the motor and a new long workpiece section clamped in the now vacant tailstock to permit repetition of the abovedescribed process. This latter procedure would be especially beneficial for rod or wire splicing wherein the joined sections are eventually formed in a large coil.

FIG. 8 illustrates a modified embodiment of the invention wherein the drive motor is free-floating or slidably supported on the guide rods rather than being fixedly secured thereto as shown in the embodiment of FIGS. 1 and 2. Those portions of the machine shown in FIG. 8 which are identical with the machine 10 of FIGS. 1 and 2 carry the same reference numeral with a prime symbol added.

FIG. 8 illustrates a free floating, hollow shaft, electrical induction, drive motor, shown generally at 24, slidably supported upon the guide rods 20'. FIG. 9 is a cross-sectional view ofthe motor 24' taken on the line lX-IX of FIG. 8.

As shown in FIG. 9 the motor housing 40 is provided at each side with tubular extensions 42 which are preferably formed integrally with the motor housing 40. The guide rods 20' are shown disposed in the bores of the tubular members 42 which are mounted over the guide rods through the employment of linear motion bearings 44.

Due to this hearing arrangement, during a welding operation the center drive motor 24' floats upon the guide bars 20' and the tailstock assemblies 30' and 32' are simultaneously actuated by the rams 34' and 36' to engage workpieces (not shown) held in the tailstocks with rapidly rotating workpieces held in the center drive motor. It should be understood that during the welding operation the free-floating motor 24' is balanced in a position between the 'tailstocks 30' and 32 since the thrust of the rams 34' cancels out the thrust of the rams 36'.

FIG. illustrates a modified embodiment of the invention shown in FIG. 8 wherein a free-floating center drive friction welder is adapted to make a single weld rather than two welds. When making dual welds (one at each end) with a free-floating center drive motor (as in FIG. 8) very little thrust is transmitted to the bearings of the center drive spindle. However, when making a single weld at one end of the free-floating center drive welder, provision must be made to locate the spindle to permit thrust loading at the weld interface and relieve the spindle bearings of thrust loads which might exceed their designed thrust resistance. As will be described in greater detail below, the embodiment of FIG. 10 employs a supplemental thrust bearing arrangement 199 to counteract thrust loading at the interface of a single pair of weld members disposed at one end of the machine. The thrust unit is a low-inertia device to minimize its influence on the deceleration rate of the spindle.

Those portions of the machine shown in FIG. 10 which are identical with the machine 10' shown in FIG. 8 carry the same reference numeral. As shown in FIG. 10 the thrust rams 34, tailstock assembly 30 etc., to the left of the free-floating drive motor 24' remain as described previously. The tailstock assembly to the right of the drive motor is not shown, and in fact may preferably be removed from the machine when performing a single weld operation.

The drive motor in FIG. 10 is free-floating on the tie bars and the supplemental thrust bearing means 199 are provided for limiting movement of the motor to the right so that the thrust rams 34' can provide adequate thrust loading at the interface of the weld members held in tailstock and rotating chuck 60. In addition the supplemental thrust bearing means 199 should operate to effectively prevent damaging thrust loads from being transmitted to the spindle bearings of drive motor 24.

Referring now to FIG. I0 in conjunction with FIG. 11 the flange element 64' at the right of spindle 56 has nothing attached to it and is preferably provided with a friction face 65. The supplemental thrust bearing means 199 comprises a flange 200 which is also provided with a friction face 202 adapted for frictional engagement with the friction face 65 of flange 64' during a welding operation. The flange element 200 is secured by bolts to a rotatable shaft 204 which is adapted for limited longitudinal movement in a chamber 206 defined by a housing 208. As shown in F IG. 12 the housing 208 is fixedly clamped to the tie bars 20 by bolted clamp elements 209.

A suitable sealing element, such as a labyrinth seal shown generally at 210 insures a fluidtight connection where the shaft 204 enters the housing 208. A fluid passageway 212 leads away from the seal 210 to a drain conduit 214. A first roller bearing element 216 is provided between a shoulder 218 on the shaft 204 and an annular retainer ring 220 secured to the housing 208. A second and similar bearing element 222 is provided between the shaft 204 and the wall of cavity 206 and is held in place between an annular shoulder 224 and a snap ring 226.

The cavity 206 is provided with a reduced diameter portion 220 into which the end 230 of the shaft 204 projects in a pistonlike manner. Preferably, the reaction surface of the shaft end 230 is equal to the reaction surfaces associated with the thrust rams 34. A very small annulus 232 is provided between the shaft end 230 and the wall of reduced diameter cavity 228 to provide a controlled fluid leakage path out of reduced cavity 228 into main cavity 206. A pressure fluid inlet port is provided at 234 for the admission of pressure fluid during a welding operation as will be described below.

A welding operation of the device shown in FIGS. 10 and 11 is carried out as follows. Assuming that free-floating motor 24' is rotating at the proper speed the hydraulic controls 14' are actuated which supplies fluid to the tailstock rams 34 and the stationary workpiece held in the tailstock chuck is advanced along the guide bars 20' toward the rotating workpiece held in chuck 60'. Simultaneously fluid pressure is admitted through the port 234 to the cavity 228 of the supplemental thrust means 199.

After the weld pieces come into contact the motor 24 will move rightwardly under the thrust from rams 34 until the flange element 64 comes into contact with flange element 200 of the shaft 204. The shaft 204 will now begin rotating and a hydrostatic thrust bearing will be established between shaft end 230 and cavity 228 to offset the thrust applied by the tailstock rams 34'. Since the thrust loading imposed by rams 34 is counteracted by the hydrostatic bearing established in member 199 no appreciable amount of thrust load is exerted on the bearings of motor 24'.

The supplemental thrust bearing means 199 of FIGS 10, 11 and 12 has been illustrated as a hydrostatic thrust bearing unit. However, it is to be understood that other suitable thrust bearing elements could be utilized. The only requirements for such a thrust bearing unit are the capability of permitting free rotation for the thrust shaft 204 and simultaneously absorbing the thrust from rams 34' so that this thrust force does not damage the motor bearings which permit rotation of the motor shaft 56.

It should also be understood that a supplemental thrust bearing means similar to the unit at 199 could be used with the fixed center drive embodiment of FIGS. 1 and 2 when that embodiment is adapted to make a single weld rather than two welds. The supplemental thrust assembly 199 could be installed on the guide rods 20 with the friction surface abutting the motor flange to relieve thrust loads imposed on the motor bearings when making welds at only one end of the center drive 24.

While we have illustrated and described preferred embodiments of our invention, it is to be understood that these are capable of variation and modification, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the following claims.

l. A friction welding machine comprising:

a main frame;

guide means extending longitudinally of the frame;

a single center drive means mounted on the guide means centrally of the machine frame;

said center drive means comprising a motor having a rotor; a workpiece holding spindle rigidly connected to the rotor and projecting outwardly from each side of the rotor;

spindle chuck means rigidly mounted on the spindle for holding a spindle workpiece for rotation with said rotor during engagement of the spindle workpiece with tailstock workpieces at the ends of the spindle;

a pair of tailstock assemblies mounted for sliding movement on the guide means on either side. of the center drive means, each tailstock having tailstock chuck means for holding a tailstock workpiece against rotation; loading means connected to each of the tailstock assemblies for moving the tailstock assemblies inwardly toward the motor to press the two tailstock workpieces against the spindle workpiece;

and wherein the rigid connection between the rotor and spindle chuck means utilizes all of the kinetic energy of the decelerated motor rotor as the two welds are produced with the tailstock workpieces at the ends of the spindle.

2. A friction welding machine as set forth in claim 1 wherein the center drive means is fixedly secured to the guide means to prevent movement thereof.

3. A friction welding machine as set forth in claim 1 wherein the center drive means is slidably mounted on the guide means for free-floating movement thereon.

4. A friction welding machine as set forth in claim 1 wherein said guide means comprises at least two tie bars extending longitudinally of the machine frame.

5. A friction welding machine as set forth in claim 1 wherein said rotor comprises an electrical motor.

6. A friction welding machine as set forth in claim 5 wherein said rotor comprises an electrical induction motor.

7. A friction welding machine as set forth in claim 1 wherein said rotor comprises a hollow shaft.

8. A friction welding machine as set forth in claim 1 wherein said center drive rotor is provided with a workpiece holding chuck on each end thereof; said machine further comprising, ram means for axially moving each tailstock on the guide means towards the center drive means; and means for simultaneously actuating the rams to move the workpieces held by each tailstock into engagement with the workpieces held at each end of the center drive motor, whereby axial thrust loads exerted by the rams produce a balanced condition at the center drive means.

9. A friction welding machine as set forth in claim 8 wherein said guide means comprise at least two tie bars extending longitudinally of the machine frame and said motor comprises an electrical motor.

10. A friction welding machine as set forth in claim 8 wherein said rotor comprises a hollow shaft.

11. A friction welding machine as set forth in claim 9 wherein said rotor comprises a hollow shaft.

12. A friction welding machine comprising a main frame; guide means extending longitudinally of the frame; a drive means for rotating a first workpiece relative to a second workpiece, said drive means beingcentrally mounted for free floating movement longitudinally on the guide means; said drive means including a motor, a rotor in the motor, a spindle rigidly connected to the rotor, spindle chuck means for holding said first workpiece for rotation with the spindle and rotor, and bearing means for permitting rotation of the rotor and spindle within the motor housing; a tailstock assembly mounted for sliding movement on the guide means on a first side of the drive means and having means for holding a second workpiece; loading means for axially moving said tailstock assembly along the guide means to engage said first and second workpieces, and a separate thrust bearing means, located externally of the drive means on a second side of said center drive means, for absorbing axial thrust forces transmitted through said free-floating drive means during engagement of said first workpiece with said second workpiece; whereby the maximum axial forces to which the spindle bearing means are subjected during a weld cycle are of a very low magnitude.

13. A friction welding machine as set forth in claim 12 wherein said thrust bearing means comprises a hydrostatic bearing assembly.

14. A friction welding machine as set forth in claim 12 wherein said guide means comprises at least two tie bars extending longitudinally of the frame.

15. A friction welding machine as set forth in claim 12 wherein said motor comprises an electrical induction motor.

16. A friction welding machine as set forth in claim 12 wherein said rotor shaft is hollow.

Patent No.

Inventor(s) (SEAL) Attest:

Attesting Officer EDWARD M.FLETCHER,JR.

UNITED STATES PATENT OFFICE Dated October 19, 1971 and Galvin D1 Lovd It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The original patent identified above carries the number 3,613,982 on the cover and the typewritten specification and claims, whereas all eight sheets of the drawings are identified with the incorrect number Signed and sealed this 22nd day of August 1972.

ROBERT GOTTSCHALK Commissioner of Patents ORM PO-IOSO (10-63) USCOMM-DC GOING-P69 s u s covznnmsm' Pmmmu OFFICE 1 $969 0-300-334

Claims

1. A friction welding machine comprising: a main frame; guide means extending longitudinally of the frame; a single center drive means mounted on the guide means centrally of the machine frame; said center drive means comprising a motor having a rotor; a workpiece holding spindle rigidly connected to the rotor and projecting outwardly from each side of the rotor; spindle chuck means rigidly mounted on the spindle for holding a spindle workpiece for rotation with said rotor during engagement of the spindle workpiece with tailstock workpieces at the ends of the spindle; a pair of tailstock assemblies mounted for sliding movement on the guide means on either side of the center drive means, each tailstock having tailstock chuck means for holding a tailstock workpiece against rotation; loading means connected to each of the tailstock assemblies for moving the tailstock assemblies inwardly toward the motor to press the two tailstock workpieces against the spindle workpiece; and wherein the rigid connection between the rotor and spindle chuck means utilizes all of the kinetic energy of the decelerated motor rotor as the two welds are produced with the tailstock workpieces at the ends of the spindle.

12. A friction welding machine comprising a main frame; guide means extending longitudinally of the frame; a drive means for rotating a first workpiece relative to a second workpiece, said drive means being centrally mounted for free floating movement longitudinally on the guide means; said drive means including a motor, a rotor in the motor, a spindle rigidly connected to the rotor, spindle chuck means for holding said first workpiece for rotation with the spindle and rotor, and bearing means for permitting rotation of the rotor and spindle within the motor housing; a tailstock assembly mounted for sliding movement on the guide means on a first side of the drive means and having means for holding a second workpiece; loading means for axially moving said tailstock assembly along the guide means to engage said first and second workpieces, and a separate thrust bearing means, located externally of the drive means on a second side of said center drive means, for absorbing axial thrust forces transmitted through said free-floating drive means during engagement of said first workpiece with said second workpiece; whereby the maximum axial forces to which the spindle bearing means are subjected during a weld cycle are of a very low magnitude.