Roll forming machine

Abstract

Changing of a horizontal roll in a horizontal roll stand involving readjustment of an amount of pressing is to be done readily and promptly. In order to achieve this, a horizontal roll stand 10 with a pair of built-in upper and lower horizontal rolls 11 is configured to retreat toward one side across a forming line. A fixed stand 40 stands upright on a counter-retreating side of the forming line. An overhang part 42 of the fixed stand 40 jutting out over the forming line is provided with a pressure device 43 that applies a pressing force to the horizontal rolls 11. The horizontal roll stand 10 includes a horizontal roll housing 12 with an opened top, receives the pressing force from the pressure device 43 via the opened top, and retreats to the outside of the forming line while the pressure device 43 is left on the forming line. The overhang part 42 of the fixed stand 40 is engaged with the horizontal roll housing 12 of the horizontal roll stand 10 to support the horizontal roll housing 12 in the forming line.

Claims

1. A roll forming machine comprising: a movable horizontal roll stand including one or a plurality of horizontal roll housings in each of which a pair of upper and lower horizontal rolls is housed, the horizontal roll housing including a pair of roll chock receivers with a top opened for removing the horizontal rolls upward through the opened top of the horizontal roll housing, the horizontal roll housing being configured to retreat from a position on a forming line to a position outside of the forming line on a retreating side that is one side of the forming line perpendicular to the forming line while being mounted on a carriage; a fixed stand with an overhang part jutting out from a main frame standing upright outside of the forming line on a counter-retreating side that is an opposite side of the forming line from the retreating side to extend over the forming line and being supported in a cantilever style by the main frame; and first and second roll chocks configured to respectively support opposite ends of the upper horizontal roll, wherein the horizontal roll housing which is returned to the position on the forming line is housed directly below the overhang part of the fixed stand, and the overhang part is provided with: first and second screw down devices for applying pressing forces respectively to the first and second roll chocks of the upper horizontal roll in the horizontal roll housing which is at the position on the forming line via the opened top, the first and second screw down devices being left at the overhang part when the horizontal roll housing is retreated to the position outside of the forming line; and housing supports engaged with the opened top of the horizontal roll housing in the forming line to support and lock the horizontal roll housing, wherein the overhang part of the fixed stand is supported in such a manner as to be movable together with the first and second screw down devices and the housing supports in an up-down direction relative to the fixed stand.

2. The roll forming machine according to claim 1, wherein the retreating side is an operation side for changing of the horizontal rolls in the horizontal roll stand.

3. The roll forming machine according to claim 1, wherein the housing supports provided to the overhang part are slidable supports to be engaged sideway with a forming line upstream portion and a forming line downstream portion of the horizontal roll housing in response to motion of the horizontal roll housing of the horizontal roll stand of returning from the position outside of the forming line on the retreating side of the forming line into the forming line.

4. The roll forming machine according to claim 1, wherein the housing supports provided to the overhang part are slidable supports to be engaged sideway with a forming line upstream portion and a forming line downstream portion of the horizontal roll housing in response to motion of the horizontal roll stand of returning from the retreating side of the forming line into the forming line.

5. The roll forming machine according to claim 1, wherein a vertical roll stand with a pair of right and left side rolls is mounted on the carriage of the horizontal roll stand to be adjacent to the horizontal roll housing from upstream and/or downstream of the forming line.

6. The roll forming machine according to claim 4, wherein the retreating side is an operation side for changing of the horizontal rolls in the horizontal roll stand.

7. The roll forming machine according to claim 4, wherein a vertical roll stand with a pair of right and left side rolls is mounted on the carriage of the horizontal roll stand to be adjacent to the horizontal roll housing from upstream and/or downstream of the forming line.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a front view of a roll forming machine showing an embodiment of the present invention and showing a state in which a movable stand array is combined;

(2) FIG. 2 is a front view of the roll forming machine according to the embodiment showing a state in which the movable stand array is separated;

(3) FIG. 3 is a perspective view of the roll forming machine according to the embodiment showing a state in which the movable stand array is combined;

(4) FIG. 4 is a perspective view of the roll forming machine according to the embodiment from a different angle showing a state in which the movable stand array is combined;

(5) FIG. 5 is a perspective view of the roll forming machine according to the embodiment from a different angle showing a state in which the movable stand array is separated;

(6) FIG. 6 is a side view of a principal part of the roll forming machine according to the embodiment in a non-pressed state;

(7) FIG. 7 is a side view of the principal part of the roll forming machine according to the embodiment in a pressed state;

(8) FIG. 8 is a back view of a fixed stand of the roll forming machine according to the embodiment;

(9) FIG. 9 is a perspective view showing how the roll forming machine according to the embodiment is used; and

(10) FIG. 10 is a perspective view showing how a different roll forming machine is used.

EMBODIMENTS FOR CARRYING OUT INVENTION

(11) An embodiment of the present invention will be described below. A roll forming machine according to the embodiment is a forming roll stand array arranged in a manufacturing line of manufacturing electric resistance welded pipes, more specifically, a fin-pass (hereinafter called FP) roll stand array arranged upstream of a squeeze (hereinafter called SQ) roll stand.

(12) In the following description, a direction of a forming line is expressed as an x direction, a horizontal direction at a right angle to the x direction is expressed as a y direction, and a vertical direction at a right angle to the x direction is expressed as a z direction. Further, the x direction corresponding to the forming line, the y direction, and the z direction are called a front-rear direction, a right-left direction or sideway, and an up-down direction respectively. A horizontal roll in an FP roll stand unit is a driven roll and driven to rotate by a roll driving mechanism arranged on one side of the forming line. For this reason, a side on which the roll driving mechanism is arranged is called a “driving side” of the forming line, and its opposite side is called an “operation side” of the forming line.

(13) A front side of the forming line means an upstream side of the forming line, and a front part of the forming line means an upstream part of the forming line. Likewise, a rear side of the forming line means a downstream side of the forming line, and a rear part of the forming line means a downstream part of the forming line.

(14) As shown in FIGS. 1 and 2, a roll forming machine A is composed of a movable stand array B to move back and forth between the interior of the forming line and the operation side of the forming line, and a fixed unit C installed on the forming line and extending toward the driving side of the forming line. The roll forming machine A includes a main base D arranged directly below the forming line and extending toward the driving side of the forming line. The main base D is combined with an intermediate stage E arranged closer to the operation side than the main base D across the forming line and a standby stage F arranged still closer to the operation side than the intermediate stage E, thereby forming a stand array changing system.

(15) As shown in FIGS. 3 to 5, the movable stand array B in the roll forming machine A includes two horizontal roll stands 10 arranged in vertical rows in the direction of the forming line, and two vertical roll stands 20 also arranged in vertical rows in the direction of the forming line. The two horizontal roll stands 10 and the two vertical roll stands 20 are mounted alternately along the forming line on a common carriage 30.

(16) The carriage 30 is located on rails 31 placed on the main base D in the roll forming machine A, particularly from a position directly below the forming line to extend over the intermediate stage D on the operation side. The carriage 30 is driven by a cylinder 32 installed as a carriage driving mechanism on the driving side of the forming line to move for retreat from a position on the forming line toward the operation side, and to move for return from the retreating position into the forming line. This further moves the movable stand array B between the interior of the forming line and a retreating side of the forming line, more specifically, between the interior of the fixed unit C of the roll forming machine A and a position on the standby stage F.

(17) The horizontal roll stand 10 includes a pair of upper and lower horizontal rolls 11, 11. The horizontal rolls 11, 11 are driven rolls. With the horizontal roll stand 10 in a retreating state in the forming line, the horizontal rolls 11, 11 are coupled to the roll driving mechanism (not shown) via a pair of upper and lower intermediate joints 50, 50 installed on the driving side of the forming line, thereby driving the horizontal rolls 11, 11 to rotate.

(18) The horizontal rolls 11, 11 are housed in a horizontal roll housing 12 with an opened top. In this state, the horizontal rolls 11, 11 are mounted on the carriage 30. The horizontal roll housing 12 includes a pair of right and left U-shaped members 12a, 12a fixed on the carriage 30. As shown in FIGS. 6 and 7, the right and left U-shaped members 12a, 12a are each formed into a U shape with an opened top as viewed from a side surface. The U-shaped members 12a, 12a support the upper and lower horizontal rolls 11, 11 by housing roll chocks 11a, 11a of the upper and lower horizontal rolls 11, 11 between front and rear vertical parts 12b, 12b.

(19) To avoid contact of the upper horizontal roll 11 with the lower horizontal roll 11, the upper horizontal roll 11 is supported elastically at a predetermined height separated from the lower horizontal roll 11. For this support, an elastic mechanism 11b such as a coil spring is interposed between the upper and lower roll chocks 11a, 11a. At each of the right and left U-shaped members 12a, 12a, recesses 12c for engagement of hook-shaped housing supports 42c are provided at an upper front surface of the front-side vertical part 12b and an upper rear surface of the rear-side vertical part 12b, as will be described in detail later.

(20) The fixed unit C includes a pair of front and rear fixed stands 40, 40 installed on the main base D in corresponding relationships with the horizontal roll stands 10, 10. As shown in FIG. 8, each fixed stand 40 is composed of a main frame 41 standing upright on the driving side of the forming line, and an overhang part 42 jutting out from the head of the main frame 41 to extend over the forming line (namely, supported in a cantilever style by the main frame 41). After the horizontal roll stand 10 returns to the interior of the forming line, the horizontal roll stand 10 is housed directly below the overhang part 42. The pair of upper and lower intermediate joints 50, 50 is attached to the main frame 41.

(21) The overhang part 42 includes a base plate 42b horizontally supported by a pair of front and rear horizontal beams 42a, 42a. The front and rear horizontal beams 42a, 42a are fixed parts coupled to the main frame 41. As shown in FIGS. 6 and 7, the base plate 42b is a movable plate supported to be movable in the up-down direction by the front and rear horizontal beams 42a, 42a. A pair of right and left screw down devices 43, 43 are attached in downward-pointed positions to the movable base plate 42b. The base plate 42b has a front edge to which a pair of front-side right and left housing supports 42c, 42c is attached, and a rear edge to which a pair of rear-side right and left housing supports 42c, 42c is also attached.

(22) The front-side housing supports 42c, 42c each have a hook shape with a lower portion projecting rearward. With the horizontal roll stand 10 housed directly below the overhang part 42, projections 42d, 42d of the front-side housing supports 42c, 42c are engaged from the front side with front-side recesses 12c, 12c formed at the front surfaces of the front-side vertical parts 12b, 12b of the right and left U-shaped members 12a, 12a. The rear-side housing supports 42c, 42c each have a hook shape with a lower portion bent frontward. With the horizontal roll stand 10 housed directly below the overhang part 42, projections 42d, 42d of the rear-side housing supports 42c, 42c are engaged from the rear side with rear-side recesses 12c, 12c formed at the rear surfaces of the rear-side vertical parts 12b, 12b of the right and left U-shaped members 12a, 12a.

(23) During return of the horizontal roll stand 10 from the operation side of the forming line into the forming line, the respective projections of the front-side hook-shaped housing supports 42c, 42c are fitted and engaged sideway in a sliding manner with the front-side recesses 12c, 12c as the forming line upstream portions of the horizontal roll housing 12, and the respective projections 42d of the rear-side hook-shaped housing supports 42c, 42c are fitted and engaged sideway in a sliding manner with the rear-side recesses 12c, 12c as the forming line downstream portions of the horizontal roll housing 12. To achieve these engagements easily and smoothly, the recesses 12c, 12c are placed at greater heights, especially than the respective projections 42d of the housing supports 42c, 42c.

(24) With the horizontal roll stand 10 housed directly below the overhang part 42, the right and left screw down devices 43, 43 attached in downward-pointed positions to the base plate 42b are configured to apply pressing forces from above to the right and left U-shaped members 12a, 12a, particularly to the right and left roll chocks 11a, 11a of the upper horizontal roll 11. A motor 44, which is a driving mechanism common to the screw down devices 43, 43, is located closer to the driving side than the screw down devices 43, 43 and attached to the base plate 42b together with the screw down devices 43, 43.

(25) The upper and lower intermediate joints 50, 50 are connected to the horizontal rolls 11, 11 in the horizontal roll stand 10 and attached to the main frame 41 of the fixed stand 40. The upper and lower horizontal rolls 11, 11 become connected to the upper and lower intermediate joints 50, 50 by inserting rectangular columnar slidable input shafts 11c, 11c (see FIG. 9) provided at an edge of the driving side into the upper and lower intermediate joints 50, 50 (see FIG. 8), thereby coupling the upper and lower horizontal rolls 11, 11 to the roll driving mechanism (not shown) provided still closer to the driving side than the intermediate joints 50, 50.

(26) The vertical roll stand 20, which is mounted on the carriage 30 in an adjacent position to the horizontal roll stand 10, includes a pair of built-in right and left vertical rolls 21, 21. The dimension of a gap between the right and left vertical rolls 21, 21 is set by a roll position adjusting motor 22 installed on the driving side of the forming line. More specifically, a gap adjuster 23 provided in the vertical roll stand 20 is connectable to a coupling 24 connected to the gap adjusting motor 22. With the roll stand 20 in a returning state in the forming line, the gap adjuster 23 is connected to the motor 22 via the coupling 24. With the roll stand 20 in a retreating state outside the forming line, the gap adjuster 23 is disconnected from the coupling 24.

(27) The standby stage F, which is arranged still closer to the operation side than the intermediate stage E, includes a horizontal turntable 60. The turntable 60 is rotatably supported on a base 61 and driven to rotate by a motor-powered rotation driving mechanism 62 attached to a side surface of the base 61. A first standby stage 63a is defined on one of sides across a center of rotation on the turntable 60, and a second standby stage 63b is defined on the other side. The turntable 60 is driven to rotate by the rotation driving mechanism 62 for selectively making the first standby stage 63a or the second standby stage 63b face the roll forming machine A in the forming line.

(28) First rails 64a are placed on the first standby stage 63a. The first rails 64a are to be connected to the rails 31 on the intermediate stage E extending from the main base C when the first standby stage 63a faces the roll forming machine A. Likewise, second rails 64b are placed on the second standby stage 63b. The second rails 64b are to be connected to the rails 31 on the intermediate stage E extending from the main base C when the second standby stage 63b faces the roll forming machine A.

(29) The configuration of the roll forming machine A according to the embodiment and that of the stand array changing system using the roll forming machine A have been described above. In the following, the characteristics of the roll forming machine A in terms of its operation and effect will be shown clearly by describing the motion of the stand array changing system by referring to FIG. 9.

(30) In a state shown in FIG. 9, the first standby stage 63a of the standby stage F is empty in the absence of a movable stand array. In the second stage 63b, a movable stand array B′ of a different type from the movable stand array B in the roll forming machine A is placed.

(31) The movable stand array B and the movable stand array B′ differ from each other only in the dimensions of forming hole dies of the upper and lower horizontal rolls 11, 11 assembled in each of the two horizontal roll stands 10, 10 and the dimensions of forming hole dies of the right and left vertical rolls 21, 21 assembled in each of the two right and left vertical roll stands 20, 20, and are the same in the other configuration.

(32) As shown in FIGS. 1, 3, 4, and 9, in a step of manufacturing an electric resistance welded pipe, the movable stand array B in the roll forming machine A, namely, the two horizontal roll stands 10 and the two vertical roll stands 20 aligned on the carriage 30 in the direction of the forming line, are present in the forming line. More specifically, the movable stand array B is combined with the fixed unit C and housed directly below the overhang part 42 of the fixed stand 40. In each horizontal roll stand 10, the upper and lower horizontal rolls 11, 11 are coupled via the intermediate joints 50, 50 arranged on the driving side of the forming line to the roll driving mechanism (not shown) still closer to the driving side, thereby driving the upper and lower horizontal rolls 11, 11 to rotate.

(33) As shown in FIGS. 6 and 7, the right and left screw down devices 43, 43 provided to the overhang part 42 of the fixed stand 40 adjust the upper horizontal roll 11 in the horizontal roll stand 10, more specifically, adjust the right and left roll chocks 11a, 11a of the upper horizontal roll 11 to predetermined positions. At this time, as the right and left U-shaped members 12a, 12a of the horizontal roll housing 12 of the horizontal roll stand 10 are opened upward, the right and left roll chocks 11a, 11a are pressed directly via the opened tops of the right and left U-shaped members 12a, 12a.

(34) As a result of this pressing, the elastic mechanism 11b interposed between the upper and lower roll chocks 11a, 11a contracts, and resultant reaction force (upward reaction force) is applied to the base plate 42b of the overhang part 42 to lift the base plate 42b. By doing so, the front-side hook-shaped housing supports 42c, 42c and the rear-side hook-shaped housing supports 42c, 42c attached to the base plate 42b are lifted to lock the horizontal roll housing 12.

(35) Here, the base plate 42b is lifted for locking the horizontal roll housing 12 only by applying pressure using the right and left screw down devices 43, 43. As an alternative to this or in addition to this, the base plate 42b can be lifted for locking the horizontal roll housing 12 using a clamp cylinder attached to the base plate 42b side or to the horizontal roll housing 12 side.

(36) During forming, large upward reaction force for the forming is applied to the upper horizontal roll 11 and transmitted to the overhang part 42. In this regard, as the overhang part 42 is coupled to the horizontal roll housing 12 using the front and rear housing supports 42c, 42c, the reaction force for the forming applied to the overhang part 42 is reduced significantly. As a result, the configuration of the fixed stand 40 including the overhang part 42 is simplified while high rigidity is ensured.

(37) At the vertical roll stand 20, the gap adjuster 23 is connected to the coupling 24 arranged on the driving side of the forming line to be coupled to the roll position adjusting motor 22. As a result, the dimension of the gap is set at a predetermined value.

(38) If roll changing is necessitated by the change in size of an electric resistance welded pipe to be manufactured, to stop pressing using the screw down devices 43, 43, the motor 44 mounted on the overhang part 42 is actuated at the horizontal roll stand 10. In response to this, the horizontal roll stand 10 is released from the locking using the overhang part 42, namely, the locking using the front-side hook-shaped stand supports 42c, 42c and further using the rear-side hook-shaped stand supports 42c, 42c.

(39) In this state, the cylinder 32 installed on the driving side of the forming line is actuated to move the carriage 30 for retreat toward the operation side of the forming line. More specifically, the carriage 30 is pushed onto the first standby stage 63a of the turntable 60 at the standby stage F. By doing so, the movable stand array B in the roll forming machine A is moved for retreat onto the first stage 63a of the turntable 60.

(40) At this time, while the right and left screw down devices 43, 43 are left at the overhang part 42 of the fixed stand 40, the horizontal roll stand 10 moves for retreat onto the first standby stage 63a of the turntable 60. The front-side hook-shaped stand supports 42c, 42c are slidable supports to be engaged from the front side with the front-side vertical members 12b, 12b of the right and left U-shaped members 12a, 12a as the forming line upstream portions of the horizontal roll housing 12, and the rear-side hook-shaped stand supports 42c, 42c are slidable supports to be engaged from the rear side with the rear-side vertical parts 12b, 12b of the right and left U-shaped members 12a, 12a as the forming line downstream portions of the horizontal roll housing 12. Thus, these supports 42c do not hinder the motion of the horizontal roll stand 10 of retreating to the outside of the forming line.

(41) In response to the retreating motion of the horizontal roll stand 10, the respective input shafts 11c, 11c of the upper and lower horizontal rolls 11, 11 of this horizontal roll stand 10 are pulled out of the upper and lower intermediate joints 50, 50 arranged on the driving side of the forming line to separate these horizontal rolls 11, 11 from the roll driving mechanism (not shown).

(42) At the vertical roll stand 20, this vertical roll stand 20 retreats toward the operation side of the forming line together with the horizontal roll stand 10. As a result, the gap adjuster 23 is separated from the coupling 24 and then separated from the roll position adjusting motor 22.

(43) When the movable stand array B in the roll forming machine A moves for retreat onto the first retreat stage 63a of the turntable 60, the turntable 60 makes a half turn to make the second retreat stage 63b face the roll forming machine A. Then, the cylinder 32 is actuated in the opposite direction to pull the movable stand array B′ placed on the second standby stage 63b of the turntable 60 into the fixed unit C of the roll forming machine A.

(44) At this time, at the horizontal roll stand 10, the front-side hook-shaped stand supports 42c, 42c attached to the overhang part 42 of the fixed stand 40 are engaged sideway in a sliding manner with the front-side recesses 12c, 12c of the right and left U-shaped members 12a, 12a, and the rear-side hook-shaped stand supports 42c, 42c are also engaged sideway in a sliding manner with the rear-side recesses 12c, 12c of the right and left U-shaped members 12a, 12a.

(45) At the same time, the input shafts 11c, 11c of the upper and lower horizontal rolls 11, 11 are inserted into the upper and lower intermediate joints 50, 50 arranged on the driving side of the forming line to be coupled to the roll driving mechanism.

(46) At the vertical roll stand 20, the gap adjuster 23 is connected to the coupling 24 to be coupled to the roll position adjusting motor 22.

(47) As a result, the movable stand array B in the roll forming machine A is replaced with the different movable stand array B′, thereby changing the horizontal rolls 11, 11 of the horizontal roll stand 10 and the vertical rolls 21, 21 of the vertical roll stand 20 simultaneously. Changing of the horizontal rolls 11, 11 does not require removal of the screw down device 43 from the horizontal roll stand 10, so that the horizontal rolls 11, 11 are changed easily.

(48) For restarting manufacture of electric resistance welded pipes, pressing forces are applied from the right and left screw down devices 43, 43 to the upper horizontal roll 11 at the horizontal roll stand 10. While the horizontal roll stand 10 is retreating on the operation side of the forming line, the right and left screw down devices 43, 43 still remain in the forming line and retain operating data about an amount of pressing. Thus, pressing forces are not required to be adjusted again for application of the pressing forces to the changed horizontal roll 11. This allows roll changing to be done promptly and efficiently.

(49) At the movable stand arrays B and B′, the upper and lower horizontal rolls 11, 11 of the horizontal roll stand 10 are changed outside the forming line, if necessary. The horizontal roll housing 12 of the horizontal roll stand 10 is opened upward, so that the horizontal rolls 11, 11 are changed readily through this opened top by crane lifting, for example.

(50) In this way, in the roll forming machine A, changing of the horizontal rolls 11, 11 in the horizontal roll stand 10 involving readjustment of an amount of pressing is done readily and promptly. Further, the horizontal roll stand 10 has a simplified configuration and is reduced in size and weight easily. Thus, in trying to locate a plurality of stands, it becomes possible to reduce a pitch between the stands to shorten a line length. Together with the configuration of the horizontal roll stand 10, the configuration of the fixed stand 40 is simplified to allow significant reduction in total cost.

(51) FIG. 10 shows a different stand array changing system. This stand array changing system is a linearly movable system and includes a standby stage G arranged parallel to the operation side of the forming line. The standby stage G is a linearly movable carriage 70 located on rails 71 parallel to the forming line and is driven by a motor-powered linear driving mechanism 72 installed outside the rails 71 to move back and forth along the forming line.

(52) In a traveling direction of the standby stage G, the standby stage G has a first half functioning as a first standby stage 73a and a rear half functioning as a second standby stage 73b. The linearly movable carriage 70 in the movable stage 70 is linearly driven by the linear driving mechanism 72 for selectively making the first standby stage 73a or the second standby stage 73b adjoin the roll forming machine A in the forming line.

(53) First rails 74a are placed on the first standby stage 73a. The first rails 74a are to be connected to the rails 31 in the roll forming machine A when the first standby stage 73a adjoins the roll forming machine A in the forming line. Likewise, second rails 74b are placed on the second standby stage 63b. The second rails 74b are to be connected to the rails 31 in the roll forming machine A when the second standby stage 63b adjoins the roll forming machine A in the forming line.

(54) In a state shown in FIG. 10, the first standby stage 73a is empty in the absence of a movable stand array. A movable stand array H′ of a different type from a movable stand array H in the roll forming machine A is placed on the second standby stage 73b.

(55) Each of the movable stand arrays H and H′ is a sizing (SZ) roll stand array arranged downstream of an SQ roll stand, and includes three horizontal roll stands 10 and three vertical roll stands 20 arranged alternately on the carriage 30 along the forming line. The movable stand array H and the movable roll stand array H′ differ from each other only in the dimensions of forming hole dies of the upper and lower horizontal rolls 11, 11 assembled in each of the three horizontal roll stands 10 and the dimensions of forming hole dies of the right and left vertical rolls 21, 21 assembled in each of the three vertical roll stands 20, and are the same in the other configuration.

(56) For roll changing, with the first standby stage 73a on the carriage 70 adjoining the roll forming machine A in the forming line, particularly adjoining the movable stand array H in the roll forming machine A, the cylinder 32 in the roll forming machine A is actuated to push the carriage 30 in the roll forming machine A onto the first standby stage 73a of the carriage 70. This moves the movable stand array H in the roll forming machine A for retreat onto the first standby stage 73a. When the movement for retreat is finished, the carriage 70 moves frontward to make the second standby stage 73b adjoin the roll forming machine A. Next, the cylinder 32 is actuated in the opposite direction to pull the movable stand array H′ on the second standby stage 73b into the fixed unit C of the roll forming machine A.

(57) As a result, the movable stand array H is replaced with the movable stand array H′ in the roll forming machine A. In this way, the roll changing is finished. On the linearly movable carriage 70 of the standby stage G, rolls are changed in the movable stand array H on the first standby stage 73a or the movable stand array H′ on the second standby stage 73b, if necessary. These rolls are to be changed readily for the reason given above.

REFERENCE SIGNS LIST

(58) A Roll forming machine B, B′, H, H′ Movable stand array C Fixed unit D Main base E Intermediate stage F, G Standby stage 10 Horizontal roll stand 11 Horizontal roll 11a Roll chock 11b Elastic mechanism 11c Input shaft 12 Horizontal roll housing 12a U-shaped member 12b Vertical part 12c Recess 20 Vertical roll stand 21 Vertical roll 22 Roll position adjusting motor 23 Gap adjuster 24 Coupling 30 Carriage 31 Rail 40 Fixed stand 41 Main frame 42 Overhang part 42a Horizontal beam 42b Base plate 42c Housing support 42d Projection 43 Screw down device 50 Intermediate joint 60 Turntable 61 Base 62 Rotation driving mechanism 63a First standby stage 63b Second standby stage 64a First rail 64b Second rail 70 Linearly movable carriage 71 Rail 72 Linear driving mechanism 73a First standby stage 73b Second standby stage 74a First rail 74b Second rail