US2593772A - Mandrel position adjustment means for pilgrim rolling mills - Google Patents

Description

A ril 22, 1952 H. LARSSON 2,593,772

MANDREL. POSITION ADJUSTMENT MEANS FOR PILGRIM ROLLING MILLS Filed July 17, 1947 .INVENTOR ATTORNEYS mandrel between the rolls.

Patented Apr. 22, 1952 UNITED STATES ATENT OF MANDR'ELPOS'ITION ADJUSTMENT MEANS FOR PILGRIM ROLLING MIPLS Gustaf Hjalmar Larsson, Alstlen, near Stockholm,

Sweden,

assignor to See Fabriks Aktiebolag,

Sandviken, Sweden, a corporation of Sweden Application July 17, 1947, Serial No. 761,558 In Sweden December 16, 1942 9 Claims.

The present invention relate to pilgrim rolling mills of the kind in which the rolls are mounted in a reciprocating roll housing and are provided with conically formed rolling grooves into which a rolling mandrel passes and over which parts of tubes are rolled out from a tube blank during the reciprocating movement of the roll housing. When the wall thickness of a part of tube requires to be varied, this can be efiected by altering (displacing) the position of the roll According to the present invention this alteration is effected by means of apneumatic device which can be actuated by the roll housing during the stroke of the latter and in 'its turn is constructed in such a way that it can act on the rolling mandrel to cause it to be withdrawn automatically from the rolls in an axial direction at desired time intervals in a certain position of the roll housings stroke. The return movement of the mandrel is preferably produced by the action of a spring.

The pneumatic device comprises a piston and a cylinder, the latter being connected to a container for compressed air which is admitted to the cylinder through a valve inserted in the connecting pipe when the valve is moved into'the opening position in consequence of the roll housing passing a certain position in its stroke (the reversing point for example) in which it actuates the valve.

The cylinder and piston are so arranged that the movement of the latter is braked immediately 7 before it reaches the cylinder cover whereby the more or less risky and troublesome direct thrust efiect on the cover iseliminated which is of particular importance in view of the fact that the piston must be displaced with considerable force. Braking is effected by constructing the arrangement in such a way that an air cushion is-formed between the piston and cylinder cover.

The piston preferably acts on a displaceabl-y controlled slide to which the rolling mandrel is fixed. As previously mentioned, the rolling mandrel is under the influence of a spring which tends to push the mandrel between the rolls. In order to prevent the mandrel from being returned by the spring before the desired time interval a locking member which may suitably be actuated by the pneumatic device is arranged to engage and lock the slide so that the latter, together with the mandrel, is retained in the withdrawn position.

In the accompanying drawing one embodiment of the invention is shown diagrammatically by way of illustration.

Referring to the drawing, l is the reciprocating roll housing which is moved to and fro in the mill stand (not shown) by means of a crank mechanism comprising a crank disk 35 driven from a suitable power source (not shown) and connecting rods 36. The rolls 3! and 38 which are provided with tapering working grooves or with detachable dies having such grooves are rockably supported in the housing I and conventional means are provided to coordinate their rocking movement mutually and with the reciprocating movement of the housing I. (For details in this respect see the revised specification of applicant's copending application Serial No. 761,557, and now Patent No. 2,537,356, granted January 9, 1951.)

The rear end of the work piece or tube blank 39 is clamped-in a chuck 40 slidably supported on a bed (not shown). The chuck 4i) together with the blank is intermittently fed forward an increment of length for each stroke of the housing I by conventional means, such as a screw spindle 4! actuated through suitable gearings accommodated in the gear housing 2; Operative connections (not shown) between said gearings and the reciprocating housing I or its driving means are provided to ensure feeding when the rolls have been turned so that the blank 39 is disengaged thereby because of the widened end portions of their working grooves. Within the tube blank there is disposed a mandrel 24 having a'tapered head portion extending through the working region of the rolls and a shaft portion extending backwards from said head portion out of the rear endof the blank.

The structure so far described comprises the usual principle elements, of a conventional pilger rolling mill which in operation will produce from a tube blank a reduced cylindrical tube with uniform wall thickness throughout its length.

Turning now to the mandrel position control device according to the embodiment oi-the present invention shown in the drawing, the mandrel shaft is extended through the blank chuck 40 and gear housing 2 to a mandrel chuck 42 in which it is clamped. The chuck 42 is attached to a slide [3 adapted tobe displaced along suitable stationary guideways (not shown). A spring 43 is disposed to urge the slide l3 to the right and hence the mandrel 24 to its foremost position between the rolls 3?, 38. To move the slide l3 in the opposite direction for the withdrawal of the mandrel 24 a certain distance, a pneumatic device is provided. This device comprises a cylinder [0 fixed to the rear end of the rolling millframee means Of 3. valve '9.

work or gear housing 2 and wherein a piston II is fitted which is provided with a piston rod |2 acting on the slide l3 in the direction opposite to that of the spring 43. Compressed air from a container 1 is admitted to the front end of the cylinder I through a pipe 8 on the opening of a spring loaded valve 6 which is opened when the mandrel 24 is to be withdrawn. To effect this opening a lever 3 which is adapted to engage the valve spindle is pivotally mounted on the rolling mill framework adjacent the reciprocating roll housing I. This lever slidably supports at its free end a pin 4 which can be actuated and moved in an axial direction by means of an electro-magnet (not shown). When so moved the pin 4 enters the path of movement of a cam surface or the like disposed on the roll housing and. then the cam surface causes the lever 3 to pivot and open the valve 6 at a certain stroke position of the roll housing, as for example when the latter approaches its turning point and the rolls have disengaged the tube blank. The compressed air which then flows into the cylinder III in front of the piston |I forces the latter and its rod I2 backwards through the cylinder, the rod I2 pushing the slide |.-3 backwards against the action of the spring 43 and causing withdrawal of the mandrel 24. A withdrawal of the mandrel 24 is thus initiated by the actuation of the electro-magnet for the .pin 4 and is thereafter automatically performed under control of the roll housing I. The piston II is provided with a small auxiliary piston I4 for which an auxiliary cylinder I5 is arranged in the cover IB of the cylinder l0. Passages I! are formed in the cover which allow a part of the air present between the piston II and cover Hi to escape from the cylinder I0 when the piston is pushed backward.

The escape of the air is regulated by means of a valve I8. When the piston II is pushed backward on account of the compressed air flowing in behind it, the auxiliary piston I4 is finally led in the auxiliary cylinder l5 whereby the latter is closed so that no air can escape from the cylinder ID by way of the auxiliary cylinder I5 through the passages I! which pass out from the auxiliary cylinder I5. As the result of this an air cushion is formed between the piston I and cover I6 (see the piston position marked on the drawing in dotted lines )which brakes the piston so that the latter does not exert a direct thrust on the cover I6. As previously mentioned, braking is regulated by means of the valve I8.

On the return stroke of the piston air escapes behind the piston through a passage regulated by This valve is adjusted in such a way that no appreciable drop of pressure takes place in the compressed air which flows in front of the piston on the backward stroke of the latter.

The slide I3 is provided with a strip 20 with which a locking pin 2| cooperates inasmuch as the pin is under the influence of a spring 22 which tends to move it into engagement with a groove 23 in the strip 20 when the slide I3 has been displaced to the left by the piston rod I2. By this means the slide can be retained in the displaced position for a desired length of time and the rolling mandrel which is fixed to the slide is thus held for the required period in the withdrawn position relatively to the rolls.

When the rolling mandrel is to be led between the rolls again a pin 25, corresponding to the previously mentioned pin 4 and carried by a lever 26 arranged in the same manner as the lever 3,

guess-7t is adjusted to cooperate with a cam surface 3.

The adjustment of the pin 25 is also efiected by means of an electro-magnet (not shown in the drawing). When the lever 26 is pivoted under the action of the cam surface 5 a spring-loaded valve 21 connected in a pipe 28 leading from the container 1 is opened. From the valve 21 a pipe 29 goes out and opens into a cylinder 30 in which a piston 3| is fitted, on the piston rod of which the previously mentioned locking pin 2| is formed. In the pipe 29 a three-way cook 32 is connected which is in direct connection with the container 1 through a pipe 33. When the threeway cook 32 is set in the position shown in the drawing and the valve 21 opens in consequence of the pivoting of the lever 26 by the cam surface 5, the piston 3| will be displaced in the cylinder 30, whereupon the locking pin 2| is drawn out of the groove 23 and the slide, together with the rolling mandrel, is pushed back by the action of the spring 43, the return of the mandrel to its foremost position is thus initiated by the actuating of the electro-magnet for the pin 25 and is then brought about automatically under control of the roll housing I as was the case with clearance when it is in its withdrawn position because of the tapering form of the mandrel and as this space or clearance at the end of a working stroke of the rolls determines the wall thickness of the finished tube this wall thickness will vary accordingly. To the right in the drawing there is shown a length of finished tube having a portion a with a relatively great wall thickness produced with the mandrel in its withdrawn position and a portion b with a relatively small wall thickness produced with the mandrel in its forward position, said two portions a and b being joined by an intermediate (transitional) portion 0 having a wall thicknes gradually decreasing from that of portion a to that of portion b- When it is desired to change the tube blank the slide I3 and rolling mandrel must be withdrawn for a distance which is at least as great as the length of the tube blank. This may be done in any already known manner and thereforedoes not require further description here. By this means, however, the locking pin 2| is released so that it is drawn out by the spring 22 and thus prevents the return of the slide I3 to its correct position. On account of this fact it is preferable that the mechanism for the withdrawal of the slide should be associated with a mechanism which returns the locking pin 2| to the initial position. This can be effected in a simple manner by reversing the three-way cook 32 so that the pipe 33 communicates with the part of the pipe 29 leading to the cylinder 30. The air from the container I will then flow in behind the piston 3| so that the locking .pin 2| is drawn back and retained in the withdrawn position until the slide has been returned to its normal position.

The three-way cock 32 may of course be located at the point at which the other controlling gear for the rolling mill is arranged, and the operation of the cock can take place automatically in conjunction withthe withdrawal of the slide for the changing of the tube blank.

Changes of a constructional nature may of course be made within the scope of the invention without departing from the principle of the latter. Thus for example, the manner in which the adjustment for actuatin the valvesis carried out and also the reversing process itself may be varied in many ways. i

I claim:

1. A pilgrim rolling mill as defined in and by claim 8 wherein the fluid operated means includes means providing a source of supply of pressure fluid, a cylinder, a piston in the cylinder, means providing communication between said .source and said cylinder, said control means including a valve, and operating means for moving the valve to open position responsive to the movement of the roll housing, said piston being operably connected with said mandrel" so that the opening of the valve moves the-piston and thereby the mandrel is withdrawn from between the rolls.

2. A rolling mill as defined in and by claim 1 wherein the operating means for the valve includes a pivoted lever engageable with the valve, abutment means carried by said lever, said roll housing having a cam surface thereon, said cam surface engaging said abutment means during the movement of the roll housing to pivot said lever to move said lever to open position. V

3. The combination of a rolling mill including a reciprocable roll housing, rolls having conically formed rolling grooves supported therein, a reciprocable rolling mandrel, cooperable with the rolls to determine wall thickness of a tube blank to be rolled, the blank passing over the mandrel and between the rolls during a rolling operation, fluid operated means operatively connected with the mandrel to move the same relative to the tube blank and the roll to produce a variation in the wall thickness of the finished tube leaving the rolls, control means responsive to the reciprocable movement of the roll housing providing automatic actuation of said fluid operated means, means for normally moving said mandrel to a forward position between the rolls and locking means cooperable with the mandrel to retain the same in the position where it is withdrawn from said rolls, said fluid operated means including a source of supply of pressure fluid, a cylinder, a piston in the cylinder, means providing communication between said source and said cylinder, said control means including a valve, and means for moving the valve to open position responsive to the movement of the roll housing, said piston being operably connected with said mandrel so that the opening of the valve moves the piston and thereby the mandrel is automatically withdrawn from between the rolls, and wherein means are provided in said cylinder for braking the movement of said piston.

4. A rolling mill as defined in and by claim 3 wherein the means for breaking the movement of the piston includes an auxiliary cylinder in said first mentioned cylinder, an auxiliary piston carried by said first mentioned piston and movable therewith into said auxiliary cylinder and means controlling the egress of air from said main cylinder so that as the auxiliary piston enters the auxiliary cylinder an air cushion is formed between the main piston and the end wall of the main cylinder immediately before the main piston completes its stroke.

5. A pilgrim rolling mill as defined in and by claim 8 wherein the fluid operatedmeans includes a source of supply ofv pressurefluid, a cylinder, a piston inv the cylinder, means providing communication between said source and said cylinder, said control means including a normally closed valve and means for moving the valve to open position responsive to the-movement of the roll housing, a displaceably controlled slide connected with the mandrel and engageable by the piston, the piston being 'movable when the valve is open to move the slide and thereby the mandrel to withdraw the mandrel from between the rolls, locking means co-operable with the slide to re- .tain the same and the mandrel in its withdrawn position, fluid operated lock releasing means including additional control means also responsive to the movement of the roll housing to release the locking means to release the slide and means normally urging said mandrel to a forward position between the rolls.

6; A pilgrim rolling mill as defined in and by claim 5 wherein the fluid operated lock releasing means and the control means therefore comprises another cylinder, a piston movable in said other cylinder, another normally closed valve controlling communication between the source of compressed air and said other cylinder, a pivoted lever engageable with said other valve, said lever being movable in response to the movement of the roll housing to open the valve to permit air to enter the said other cylinder to move the second mentioned piston, and said latter piston being operably connected to the locking means so that the movement of the said latter piston releases the locking means.

7. A rolling mill as defined in and by claim 8 wherein the fluid operated means include a source of supply of compressed air, a cylinder, a piston movable in the cylinder, a slide operably connected with the mandrel and engageable by the piston to move the mandrel in one direction, to withdraw the same, resilient means engageable with the slide for moving the same in an opposite direction, locking means co-operable with the slide to retain the same in said withdrawn position, said locking means including another cylinder an a piston therein, conduits providing communication between the source of supply of compressed air and both said cylinders, valve means disposed in said conduits including normally closed valves and control means responsive to the movement of the roll housing to operate the valves. to selectively control admission of air to the respective cylinders to respectively withdraw the mandrel on the operation of one of said valves and to withdraw the locking means on the operation of the other of said valves to permit said resilient means to move said mandrel in said opposite direction, and additional valve means in said conduits controlling admission of air to only said other cylinder to retain said locking means in released position.

8. In a pilgrim rolling mill, a reciprocable roll housing, rolls having conically formed rolling grooves therein supported in said housing, a reciprocable rolling mandrel cooperable with the rolls to determine wall thickness of a tube blank to be rolled, pushing means for feeding a blank over the mandrel and between the rolls, fluid operated means including a source of fluid under pressure, a cylinder, and a piston connected to the mandrel for withdrawing the mandrel axially from between the rolls and control means including valve means movable responsive to the reeiprocable movement of the roll housing for controlling fiuid flow from said source to said cylinder to move said piston to Withdraw said man- .drel axially from between the rolls independently of the movement of the pushing means.

9. The combination of a rolling mill including a reciprocable roll housing, rolls having conically formed rolling grooves supported therein, a reciprocable rolling mandrel cooperable with the rolls to determine wall thicknessof a tube :blank to be rolled, the blank passing over the mandrel and between the rolls during a rolling operation, fluid operated means operatively connected with the mandrel to move the same relative to the tube blank and the rolls to produce a variation in the Wall thickness of a finished tube leaving the rolls, said fluid operated means including control means responsive to the reciprocable movement of the roll housing providing automatic actuation of said fluid operated means, means normally urging said mandrel to a for- REFERENCES CITED The following references are of record in the file of this patent:.

UNITED STATES PATENTS Number Name Date 869,282 Winter Oct. 29, 1907 1,041,661 Nowak Oct. 15, 1912 1,085,964 Briggs F'eb. 3, 1914 2,021,686 Gassen Nov. 19, 1935 2,085,729 Coe July 6, 1937 FOREIGN PATENTS Number Country Date 57,432 Denmark Apr. 15, 1940 521,611 Germany Mar. 27, 1931

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