Method and apparatus for cold rolling thin wall pipe

Claim 2

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed from said rear frame structure to said front frame structure along the pipe blank feed path; rolling stand means on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; the length of frame structure which will be occupied by a mandrel rod being greater than, but substantially less than twice, the maximum length of pipe blanks to be rolled; clamping means, rigidly fastened at the rear of said frame structure, adapted to selectively clamp the rear end of the mandrel rod and axially position the mandrel head in the rolling reduction zone; pipe blank feed means, including means, adapted to surround the mandrel rod, for releasably clamping a pipe blank placed over the mandrel rod, reciprocally mounted on said intermediate frame structure for travel back and forth from positions adjacent the front and rear frame structures along the pipe blank feed path; intermediate clamping means located on said frame structure between said front end rolling reduction means and the front limit position of said blank feeding means selectively operable to clamp the outer surface of a pipe blank; and drive means connected to reciprocate said rolling reduction means and also connected to incrementally step feed said pipe blank feed means in synchronization with a predetermined stage of a reciprocation cycle of said rolling means.

Claim 3

A pipe mill, as defined in claim 1, wherein said drive means includes: a main electric motor, a reduction gearing including a vertical rocking lever connecting said motor and said rolling stand means; a speed change transmission drive including intermittent input drive gearing connected to said reduction gearing; and a feeding drive connection from said speed change transmission coupled to feed said pipe blank feed means.

Claim 4

A pipe mill, as defined in claim 2, wherein means rotatably mount both of said mandrel clamping means and said pipe blank feed means for rotation about the feed path axis; and a turning drive means from said speed change mechanism is coupled to and adapted to conjointly rotate both of said mandrel clamp and said pipe blank feed means at the same angular rate.

Claim 5

A pipe mill, as defined in claim 3, wherein said electric motor is a multi-speed, asynchronous motor and said change speed transmission includes means selectively enabling at least six different rates of feed between its input and said feeding drive connection.

Claim 6

A pipe mill, as defined in claim 3, wherein said change speed transmission includes means selectively enabling at least two angular values of step rotation oF said turning drive means.

Claim 7

A pipe mill, as defined in claim 2, wherein said pipe blank feed means includes a feed shifting body and a resiliently biased, limited shift, axially floating connecting means between said pipe blank clamping means and said body.

Claim 8

A pipe mill, as defined in claim 6, wherein said limited shift, floating connecting means rotatably mount said floating, pipe blank clamping means for rotation in said body and a turning drive means from said speed change mechanism is coupled to rotate said floating pipe blank clamping means.

Claim 9

A pipe mill, as defined in claim 7, wherein means rotatably mount said mandrel clamping means, and said turning drive means is coupled to rotate said mandrel clamp conjointly with said floating pipe blank clamping means and at the same angular rate.

Claim 10

A pipe mill, as defined in claim 8, wherein a positive axial feed device between said body and said floating pipe blank clamping means intermittently over-rides said floating shift of said floating clamp to assure an increment of feed movement during each intermittent angular rotation of said floating pipe blank clamp, and said intermittent angular rotation occurs during when said rolling stand is at end of its back stroke and the beginning of its working pass.

Claim 11

A pipe mill, as defined in claim 2, wherein said drive means includes: an auxiliary reversible electric motor; selectively shiftable coupling means, drive coupling said auxiliary motor to said speed change transmission and simultaneously disconnecting said intermittent drive gearing to enable high speed continuous forward and reverse feeding of said pipe blank feed means.

Claim 12

A pipe mill, as defined in claim 1, wherein said intermediate clamping means is a solenoid operated jaw clamp.

Claim 13

A pipe mill, as defined in claim 11, wherein operating means for said mandrel end clamp includes a component shifting between two limit positions upon selective clamping and unclamping of said mandrel end clamp; a terminal switch is mounted on said rear frame structure adjacent and actuatable by said shifting component; and safety circuits connect said terminal switch to both the main motor energizing circuit and the energizing circuit to the operating solenoid for said intermediate clamping means whereby the main motor circuit is rendered inoperative when said mandrel end clamp is opened and said solenoid circuit is rendered inoperative when said mandrel end clamp is closed.

Claim 14

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed to extend at least from said rear frame structure to said front frame structure along the pipe blank feed path; rolling stand means on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; the length of frame structure between said front and rear frame structure which will be occupied by a mandrel rod being greater than, but substantially less than twice, the maximum length of pipe blanks to be rolled; clamping means rigidly fastened relative to the rear of said frame structure adapted to selectively clamp the rear end of the mandrel rod and axial position the mandrel head in the rolling reduction zone encompassed in the front frame structure; pipe blank feed means having means to grip a pipe blank and mounted for feed movement in a path parallel to said mandrel rod to and from positions adjacent the front and rear frame structures, said pipe blank feed means adapted to continually grip a pipe blank while feeding said pipe blank a distance equal to its length; and solenoid actuated intermediate clamping means located adjacent said frame front end rolling reduction means and the front limit position of said blank feeding means selectively operable to clamp the outer surface of a pipE blank.

Claim 15

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed to extend at least from said rear frame structure to said front frame structure along the pipe blank feed path; rolling stand means on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; the length of frame structure between said front and rear frame structure which will be occupied by a mandrel rod being greater than, but substantially less than twice, the maximum length of pipe blanks to be rolled; clamping means rigidly fastened relative to the rear of said frame structure adapted to selectively clamp the rear end of the mandrel rod and axial position the mandrel head in the rolling reduction zone encompassed in the front frame structure; pipe blank feed means having means to grip a pipe blank and mounted for feed movement in a path parallel to said mandrel rod to and from positions adjacent the front and rear frame structures, said pipe blank feed means adapted to continually grip a pipe blank while feeding said pipe blank a distance equal to its length; and solenoid actuated intermediate clamping means located adjacent said frame front end rolling reduction means and the front limit position of said blank feeding means selectively operable to clamp the outer surface of a pipE blank.

Claim 16

A pipe mill, as defined in claim 13, wherein operating means for said mandrel end clamp includes a component shifting between two limit positions upon selective clamping and unclamping of said mandrel end clamp; a terminal switch is mounted on said rear frame structure adjacent and actuatable by said shifting component; and safety circuits connect said terminal switch to both the main motor energizing circuit and the energizing circuit to the operating solenoid for said intermediate clamping means whereby the main motor circuit is rendered inoperative when said mandrel end clamp is opened and said solenoid circuit is rendered inoperative when said mandrel end clamp is closed.

Claim 17

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed from said rear frame structure to said front frame structure along the pipe blank feed path; rolling stand means on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; clamping means fastened on said frame structure, adapted to selectively hold the mandrel rod and axially position the mandrel head in the rolling reduction zone; a pipe blank feed means reciprocally mounted on said intermediate frame structure for travel between the front and rear frame structure along the pipe blank feed path including means, adapted to surround the mandrel rod, for releasably clamping a pipe blank placed over the mandrel rod; and drive means connected to reciprocate said rolling reduction means and to incrementally step feed said pipe blank feed means in synchronization with a predetermined stage of a reciprocation cycle of said rolling means, said drive means including: an output crank means, a vertically disposed rocking lever with its rocking axis intermediate its arms, a connecting rod connected between said crank means and a lower arm of said rocking lever, and connecting rod means connecting an upper arm of said rocking lever to said rolling stand means; means on said frame structure mounting said crank means with its axis normal to and below the feed path axis; and means on said frame structure mounting said rocking lever with its axis normal to and below the feed path axis, the upper rocking lever arm projecting above the feed path axis and the connection between said upper lever arm and said connecting rod means to said rolling stand means disposed above the feed path axis.

Claim 18

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed from said rear frame structure to said front frame structure along the pipe blank feed path; rolling stand means on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; clamping means fastened on said frame structure, adapted to selectively hold the mandrel rod and axially position the mandrel head in the rolling reduction zone; a pipe blank feed means reciprocally mounted on said intermediate frame structure for travel between the front and rear frame structure along the pipe blank feed path including means, adapted to surround the mandrel rod, for releasably clamping a pipe blank placed over the mandrel rod; and drive means connected to reciprocate said rolling reduction means and to incrementally step feed said pipe blank feed means in synchronization with a predetermined stage of a reciprocation cycle of said rolling means, said drive means including: an output crank means, a vertically disposed rocking lever with its rocking axis intermediate its arms, a connecting rod connected between said crank means and a lower arm of said rocking lever, and connecting rod means connecting an upper arm of said rocking lever to said rolling stand means; means on said frame structure mounting said crank means with its axis normal to and below the feed path axis; and means on said frame structure mounting said rocking lever with its axis normal to and below the feed path axis, the upper rocking lever arm projecting above the feed path axis and the connection between said upper lever arm and said connecting rod means to said rolling stand means disposed above the feed path axis.

Claim 19

A pipe mill, as defined in claim 15, wherein said connecting rod is so disposed below the feed path that its path of movement is in alignment with a vertical plane through the feed path axis.

Claim 20

A pipe mill, as defined in claim 15, wherein the rocking lever structure has means providing a feed path space between its rocking axis and the end of the upper arm so a pipe blank can pass through the upper lever arm into the rolling reduction zone.

Claim 21

A pipe mill, as defined in claim 17, wherein said rocking lever includes a lever body equally balanced on opposite sides of a vertical plane through the feed path axis.

Claim 22

A pipe mill, as defined in claim 15, wherein said connecting rod means includes adjustable parallel links connected at different positions on said upper lever arm and to said rolling stand means and to a roller separator located within said rolling stand means to provide reciprocation of said rolling stand means and of said roller separator synchronized at the proper ratio.

Claim 23

A pipe mill, as defined in claim 15, wherein said upper lever arm is longer than said lower lever arm.

Claim 24

A pipe mill, as defined in claim 15, wherein said drive means further includes: a main three speed electric motor, a reduction gearing including said crank means; a speed change transmission drive including an intermittent input drive gearing connected tO said reduction gearing; and a feeding drive connection from said speed change transmission coupled to feed said pipe blank feed means in synchronization with reciprocation of said rolling stand means.

Claim 25

The method of reducing wall thickness of pipe, as defined in claim 21 including the further steps of: stopping the mill drive when the blank feeding means reaches the end of its feed path; secondarily clamping the exterior surface of the pipe blank on the feed-in side of the rolling zone and thereby maintaining the axial position of the mandrel; unclamping the mandrel rear end and the blank feeding chuck; returning the blank feeding device to its start of feed location; feeding a new pipe blank over the rear end of the mandrel and into abutment with the rear end of the preceding and secondarily clamped pipe blank disposed through the rolling zone; clamping the mandrel end clamp, releasing the secondary clamping of the preceding pipe blank and actuating feed chuck clamping of the rear end of the new pipe blank; placing the mill drive in operation to accomplish continued step by step rolling reduction of the remaining portion of the pipe blank in the rolling zone and of the succeeding pipe blank as it enters and is fed through the rolling zone.

Claim 30

A pipe mill, as defined in claim 15, wherein said rolling stand includes a roller separator and said connecting rod means includes adjustable differential motion linkage connected to said rolling stand means and to said roller separator to provide reciprocation of said rolling stand means and of said roller separator synchronized at the proper ratio.

Claim 31

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed from adjacent said rear frame structure to said front frame structure along the pipe blank feed path; a reducing roll stand reciprocally mounted on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; clamping means rigidly secured relative to said frame structure, adapted to selectively hold the mandrel rod and axially position the mandrel head in the rolling reduction zone; a pipe blank feed means reciprocally mounted on said intermediate frame structure for travel between the front and rear frame structure along the pipe blank feed path including means, adapted to surrounding the mandrel rod, for releasably clamping a pipe blank placed over the mandrel rod; and drive means connected to reciprocate said rolling reduction means and to incrementally step feed said pipe blank feed means in synchronization with a predetermined stage of a reciprocation cycle of said roll stand, said drive means including: an output crank means, a vertically disposed rocking lever with its rocking axis intermediate its arms, a connecting rod connected between said crank means and a lower arm of said rocking lever, and connecting rod means connecting an upper arm of said rocking lever to said roll stand; means on said frame structure mounting said crank means with its axis normal to and below the feed path axis; means on said frame structure mounting said rocking lever with its axis normal to and below the feed path axis, the upper rocking lever arm projecting above the feed path axis and the connection between said upper lever arm and said connecting rod means to said roll stand disposed above the feed path axis; and said front frame structure including opposed, spaced apart tracks, disposed parallel to the feed path axis; and said roll stand comprising a carriage with bearing means adapted to engage the tracks and reciprocally mount said stand on the tracks, a thick walled roller mounting head rigidly fastened in said carriage coaxial with the feed path axis, a roller separator slidably mounted within said head for reciprocation along said feed path axis relative to said head, working rollers in said separator spaced at equi-angular locations around said axis, and means on said carriage enabling attachment of said connecting rod means.

Claim 32

A pipe mill for rolling and reducing the wall thickness of pipe blanks comprising: front, rear and intermediate frame structure fixed rigidly along a pipe blank feed path, whereby a removable mandrel rod with a mandrel head on the front end may be disposed from adjacent said rear frame structure to said front frame structure along the pipe blank feed path; a reducing roll stand reciprocally mounted on said front frame structure for accomplishing a step-by-step incremental rolling reduction of the wall of a pipe blank over and forward along a mandrel head zone; clamping means rigidly secured relative to said frame structure, adapted to selectively hold the mandrel rod and axially position the mandrel head in the rolling reduction zone; a pipe blank feed means reciprocally mounted on said intermediate frame structure for travel between the front and rear frame structure along the pipe blank feed path including means, adapted to surrounding the mandrel rod, for releasably clamping a pipe blank placed over the mandrel rod; and drive means connected to reciprocate said rolling reduction means and to incrementally step feed said pipe blank feed means in synchronization with a predetermined stage of a reciprocation cycle of said roll stand, said drive means including: an output crank means, a vertically disposed rocking lever with its rocking axis intermediate its arms, a connecting rod connected between said crank means and a lower arm of said rocking lever, and connecting rod means connecting an upper arm of said rocking lever to said roll stand; means on said frame structure mounting said crank means with its axis normal to and below the feed path axis; means on said frame structure mounting said rocking lever with its axis normal to and below the feed path axis, the upper rocking lever arm projecting above the feed path axis and the connection between said upper lever arm and said connecting rod means to said roll stand disposed above the feed path axis; and said front frame structure including opposed, spaced apart tracks, disposed parallel to the feed path axis; and said roll stand comprising a carriage with bearing means adapted to engage the tracks and reciprocally mount said stand on the tracks, a thick walled roller mounting head rigidly fastened in said carriage coaxial with the feed path axis, a roller separator slidably mounted within said head for reciprocation along said feed path axis relative to said head, working rollers in said separator spaced at equi-angular locations around said axis, and means on said carriage enabling attachment of said connecting rod means.

Claim 33

A pipe mill, as defined in claim 26, wherein the rocking lever structure has means providing a feed path space between its rocking axis and the end of the upper arm so a pipe blank can pass through the upper lever arm into the rolling reduction zone.

Claim 34

A pipe mill, as defined in claim 27, wherein said rocking lever upper arm includes a dual member lever bodY equally balanced on opposite sides of a vertical plane through the feed path axis.

Claim 35

A pipe mill, as defined in claim 26, wherein said connecting rod means includes adjustable differential motion linkage connected to said roll stand and to said roller separator to provide reciprocation of said roll stand and of said roller separator synchronized at the proper ratio.

Claim 36

A pipe mill, as defined in claim 26, wherein said upper lever arm is longer than said lower lever arm.

Claim 37

A pipe mill, as defined in claim 26, wherein said drive means further includes: a main three speed electric motor, a reduction gearing including said crank means; a speed change transmission drive including an intermittent input drive gearing connected to said reduction gearing; and a feeding drive connection from said speed change transmission coupled to feed said pipe blank feed means in synchronization with reciprocation of said roll stand.