JP6577608B2 - Manufacturing method of resin reinforced metal parts - Google Patents

Description

  The present invention includes a first step of applying an uncured thermosetting adhesive to the surface of a metal part in at least two beads, and pressing the adhesive by pressing a CFRP reinforcing material against the metal part. The present invention relates to a method of manufacturing a resin-reinforced metal part including two steps and a third step of heat-curing the adhesive and bonding the CFRP reinforcing material to the metal component.

  When manufacturing a resin reinforced metal part by bonding a CFRP reinforcing material to the surface of the metal part with a thermosetting adhesive, a concave part is formed on the surface of the metal part facing the end of the CFRP reinforcing material. By increasing the thickness of the adhesive locally, the residual shear stress of the adhesive caused by the difference in thermal expansion coefficient between the metal part and the CFRP reinforcing material is reduced, and the peeling of the adhesive is prevented as described below. This is known from US Pat.

WO2016 / 129360

  Conventionally, in order to bond a CFRP reinforcing material to the surface of a metal part with an adhesive, two bead-shaped adhesives 02 are parallel to the surface of the metal part 01 while moving the nozzle held at the tip of the robot arm. After applying (see FIG. 7 (A)) and overlaying the CFRP reinforcing material 03 on the metal part 01 (see FIG. 7 (B)), the CFRP reinforcing material 03 is moved from the longitudinal center to both longitudinal ends. Then, the adhesive 02 was crushed by pressing the metal part 01 sequentially (see FIG. 7C). The reason for pressing the CFRP reinforcing material 03 from the central portion in the longitudinal direction to both ends in the longitudinal direction is to prevent the air pockets 04 from being generated due to air remaining between the two adhesives 02.

  However, when the adhesive 02 is applied to the surface of the metal component 01 in a bead shape with the moving nozzle, the bead width increases locally at the start and end portions where the moving speed of the nozzle decreases, and the start and end portions Thus, it is inevitable that the distance between the two adhesives 02 is reduced. Therefore, in the process of pressing the CFRP reinforcing material 03 from the central portion in the longitudinal direction toward both ends, the two bead-shaped adhesives 02 are mutually attached at both longitudinal ends before the pressing position reaches the both ends in the longitudinal direction. There is a problem that the air pockets 04 are formed as a result of being connected (see FIG. 7C), leaving air behind. Thus, once the air pocket 04 is formed, the air pocket 04 does not disappear even when the pressing of the CFRP reinforcing material 03 is completed (see FIG. 7D), and a metal is used to cure the adhesive 02. When the component 01 and the CFRP reinforcing material 03 are heated, the air in the air pocket 04 is thermally expanded, and the CFRP reinforcing material 03 is peeled off from the metal component 01, so that the adhesive strength may be significantly reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to prevent air pockets from being generated inside an adhesive when a CFRP reinforcing material is pressed against a metal part to pressurize the adhesive. .

  In order to achieve the above object, according to the first aspect of the present invention, a first step of applying an uncured thermosetting adhesive on the surface of a metal part in the form of at least two beads, and A resin-reinforced metal part comprising: a second step of pressing a CFRP reinforcing material against a metal part to pressurize the adhesive; and a third step of heat-curing the adhesive and bonding the CFRP reinforcing material to the metal part. In the manufacturing method, in the first step, the two bead-shaped adhesives are formed in an arch shape so as to approach each other in the longitudinal central portion and to be separated from each other at both longitudinal end portions. In the second step, the two bead-shaped adhesives are sequentially pressed from the longitudinal central portion toward both longitudinal end portions thereof. Proposed manufacturing method That.

  According to the second aspect of the present invention, in addition to the structure of the first aspect, the metal part is a vehicle body frame part of an automobile, and the adhesive after pressing has a filling rate of 80% to 100%. A method for producing a resin-reinforced metal part is proposed, wherein the maximum protrusion amount is 3.5 mm or less and the thickness is 0.5 mm ± 0.1 mm.

  According to the invention described in claim 3, in addition to the structure of claim 2, the adhesive is applied with a bead width of 40 mm or less, and is pressed with a holding time of 20 seconds or more. A method for manufacturing a resin-reinforced metal part is proposed.

  According to the invention described in claim 4, in addition to the constitution of claim 2 or claim 3, the uncured adhesive has a viscosity of 40 Pa · s to 170 Pa · s. A method of manufacturing a reinforced metal part is proposed.

  According to the invention described in claim 5, in addition to the configuration of any one of claims 1 to 4, the adhesive is an epoxy-based or urethane-based high-viscosity adhesive, and after curing A method for producing a resin-reinforced metal part is proposed, which has an initial elastic modulus with a dumbbell physical property of 1500 MPa or more and a shear strength with an adhesion to the metal part of 20 MPa or more.

  According to the invention described in claim 6, in addition to the structure of any one of claims 1 to 5, the CFRP reinforcing material includes carbon continuous fibers oriented in the longitudinal direction. A method for manufacturing a resin-reinforced metal part is proposed.

  According to the invention described in claim 7, in addition to the configuration of any one of claims 1 to 6, the metal part constitutes at least a part of a hollow closed cross-section member, and the tensile load is A method for manufacturing a resin-reinforced metal part is proposed, characterized in that the CFRP reinforcing material is bonded to the working surface.

  According to the invention described in claim 8, in addition to the configuration of any one of claims 1 to 7, the adhesive is heated in a state where the CFRP reinforcing material is temporarily fixed to the metal part. A method for producing a resin-reinforced metal part characterized by curing is proposed.

  According to the invention described in claim 9, in addition to the structure of any one of claims 1 to 8, the CFRP reinforcing material is manufactured by an autoclave method or an RTM method. A method for manufacturing a resin-reinforced metal part is proposed.

  According to the invention described in claim 10, in addition to the configuration of any one of claims 1 to 9, when the metal part has a plurality of surfaces intersecting each other, On the other hand, the manufacturing method of the resin reinforced metal component characterized by performing said 2nd process is proposed.

  According to the invention described in claim 11, in addition to the configuration of any one of claims 1 to 10, the second step includes a plurality of processes for pressing the CFRP reinforcement against the metal part. A method of manufacturing a resin-reinforced metal part is proposed, which is performed by using a pressurizer in which pressure cylinders are arranged in a straight line and sequentially operating the pressure cylinders on both ends from the pressure cylinder on the center side. The

  According to the structure of claim 1, in the first step, at least two beads of uncured thermosetting adhesive are applied to the surface of the metal part, and in the second step, the CFRP reinforcing material is applied to the metal part. Is pressed to pressurize the adhesive, and in the third step, the adhesive is heated and cured to bond the CFRP reinforcing material to the metal part to produce a resin-reinforced metal part. In the first step, the two bead-like adhesives are applied in an arch shape so as to approach each other in the longitudinal central portion and to be separated from each other at both longitudinal ends. In the second step, The two bead-shaped adhesives are sequentially pressurized from the longitudinal center to the both ends in the longitudinal direction, so that the air existing between the two bead-shaped adhesives is efficiently removed. By preventing the occurrence of air pockets by extruding, it is possible to prevent the CFRP reinforcing material from peeling off from the metal parts due to the expansion of air in the air pockets when the adhesive is heated and cured in the third step.

  According to the configuration of claim 2, the metal part is a car body frame part of an automobile, and the pressure-sensitive adhesive has a filling rate of 80% to 100%, a maximum protrusion amount of 3.5 mm or less, and a thickness of 0. Since it is 5 mm ± 0.1 mm, it is possible to maximize the strength of the vehicle body skeleton parts while minimizing the consumption of adhesive. If the filling rate of the adhesive is less than 80%, the adhesive strength is insufficient, if the filling rate of the adhesive exceeds 100%, the adhesive is wasted, and if the maximum protruding amount of the adhesive exceeds 3.5 mm, the surroundings If the adhesive adheres to the article, the working environment is deteriorated, and the adhesive strength decreases if the thickness of the adhesive is out of the range of 0.5 mm ± 0.1 mm.

  According to the third aspect of the present invention, since the adhesive is applied with a bead width of 40 mm or less and pressed for a holding time of 20 seconds or more, a filling rate of 80% is achieved with a minimum amount of adhesive. be able to.

  According to the fourth aspect of the present invention, since the uncured adhesive has a viscosity of 40 Pa · s to 170 Pa · s, it is possible to achieve a filling rate of 80% by controlling the diffusion of the adhesive by pressurization. .

  According to the configuration of claim 5, the adhesive is an epoxy or urethane high viscosity adhesive, and after curing, the initial elastic modulus with a dumbbell physical property of 1500 MPa or more and the shear strength with an adhesion to a metal part of 20 MPa or more. Therefore, it is possible to prevent the adhesive from splashing during transportation from the second process to the third process and the CFRP reinforcing material from falling off from the metal parts. The strength of the parts can be increased.

  Moreover, according to the structure of Claim 6, since the CFRP reinforcing material contains the carbon continuous fiber oriented in the longitudinal direction, the tensile strength of the CFRP reinforcing material can be effectively increased.

  According to the structure of claim 7, the metal part forms at least a part of the hollow closed cross-section member, and the CFRP reinforcing material is bonded to the surface on which the tensile load acts. Is reinforced with a CFRP reinforcing material having a high tensile strength, so that the resin-reinforced metal part can be effectively reinforced.

  According to the configuration of claim 8, since the adhesive is heat-cured in a state where the CFRP reinforcement is temporarily fixed to the metal part, the CFRP reinforcement is displaced from the metal part during conveyance from the second process to the third process. It can be prevented from falling off or falling off, and reliable bonding can be achieved.

  According to the ninth aspect of the present invention, since the CFRP reinforcing material is manufactured by the autoclave method or the RTM method, it is possible to increase the bending strength by preventing voids from being generated inside the CFRP reinforcing material.

  According to the structure of claim 10, when the metal part has a plurality of surfaces intersecting each other, the second step is performed on each surface, so that the CFRP reinforcing material having a complicated shape is securely bonded. Can do.

  According to the configuration of claim 11, the second step uses a pressurizer in which a plurality of pressurizing cylinders that press the CFRP reinforcing material against the metal part are linearly arranged, and the pressurization at both ends is applied from the central pressurization cylinder. Since the pressure cylinders are sequentially operated, the CFRP reinforcing material can be easily and reliably adhered.

It is explanatory drawing of the adhesion method of the CFRP reinforcement material with respect to a metal component. (First embodiment) It is a perspective view of a pressurizer. (First embodiment) It is a fragmentary perspective view of a center pillar inner and a center pillar outer. (First embodiment) FIG. 4 is a four-direction arrow view of FIG. 3. (First embodiment) FIG. 5 is a sectional view taken along line 5-5 of FIG. (First embodiment) FIG. 2 is a diagram corresponding to FIG. (Second to fourth embodiments) It is a figure corresponding to Drawing 1 (A)-Drawing 1 (D). (Comparative example)

First embodiment

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1A, in order to bond a CFRP (carbon fiber reinforced resin) reinforcing material 13 to a metal part 11 such as a steel plate, uncured epoxy or urethane heat is applied to the surface of the metal part 11. A curable adhesive 12 is applied in the form of two beads. The two bead-shaped adhesives 12 are curved in an arch shape having a radius R so that the mutual interval W1 is narrow at the center in the longitudinal direction and the mutual interval W2 is wide at both ends in the longitudinal direction. As shown in FIG. 1 (B), after the CFRP reinforcing material 13 as an adherend is superposed on the two bead-shaped adhesives 12 applied to the metal part 11, FIG. 1 (C), As shown in (D), after pressing the CFRP reinforcing material 13 toward the metal part 11 and crushing and diffusing the adhesive 12, the metal part 11 and the CFRP reinforcing material 13 are heated to cure the adhesive 12. Thus, the CFRP reinforcing material 13 is bonded to the metal part 11.

  FIG. 2 shows a pressurizing machine 14 for pressing the CFRP reinforcement 13 toward the metal part 11. The pressurizer 14 is supported by a flat base 15, a pair of support columns 16 erected on the base 15, a linear support member 17 connecting the upper ends of the pair of support columns 16, and the support member 17 downward. And a plurality of pressure cylinders 18 arranged on a straight line, and a flat plate-shaped pressure plate 20 connected to the lower ends of the output rods 19 of the plurality of pressure cylinders 18. The mounting interval of the pressure cylinder 18 can be arbitrarily adjusted along the support member 17 and the pressure plate 20.

  The metal part 11 and the CFRP reinforcing material 13 overlapped with the adhesive 12 are placed on the base 15 of the pressurizing machine 14, and the pressing plate 20 is overlapped on the CFRP reinforcing member 13, and the pressurizing cylinder 18. Are pressed in order from the center in the longitudinal direction to those at both ends in the longitudinal direction, and the pressure plate 20 sequentially presses the CFRP reinforcing material 13 from the center in the longitudinal direction to both ends in the longitudinal direction, thereby pushing the adhesive 12 It can be crushed and diffused to the bonding surface of the metal part 11 and the CFRP reinforcing material 13 and the air existing between the two bead-shaped adhesives 12 can be pushed out from the longitudinal center to both longitudinal ends. .

  At this time, as shown in FIG. 1 (A), the two bead-shaped adhesives 12 are curved in an arch shape, and the interval W2 between the longitudinal ends is widened. Even if W3 is enlarged as compared with other parts, in the process of pressing the CFRP reinforcing material 13 against the metal part 11 sequentially from the longitudinal center to the longitudinal ends, the two bead-shaped adhesives 12 are formed. The two ends in the longitudinal direction are not connected to each other (see FIG. 1C), and the adhesive 12 is evenly crushed without forming air pockets.

  Accordingly, when the metal part 11 and the CFRP reinforcing material 13 are heated to cure the adhesive 12, the air in the air pocket is prevented from expanding and peeling off the CFRP reinforcing material 13 from the metal part 11. The material 13 can be securely bonded to increase the strength and rigidity of the laminate of the metal component 11 and the CFRP reinforcing material 13.

  Of the filling rate of the adhesive 12, that is, the area of the bonding surface of the CFRP reinforcing material 13 facing the metal part 11 (the area of the chain line rectangle in FIG. 1D), the area filled with the compressed adhesive 12 ( The ratio of the shaded area in FIG. 1D is preferably 80% to 100%. If the filling rate is less than 80%, the adhesive strength is insufficient due to the lack of the bonding area, and if the filling rate exceeds 100%, the adhesive protrudes and is wasted.

  The maximum amount of the adhesive 12 protruding, that is, the maximum distance that the compressed adhesive 12 protrudes from the edge of the CFRP reinforcing material 13 to the outside is preferably 3.5 mm or less. As a result, it is possible to prevent the protruding adhesive 12 from adhering to surrounding articles and deteriorating the working environment. Further, the thickness of the adhesive 12 after compression is preferably 0.5 mm ± 0.1 mm, whereby the maximum adhesive strength can be obtained.

  Further, the bead width of the adhesive 12 applied to the metal part 11 is set to 40 mm or less, and the holding time after applying the adhesive 12 (time for holding the pressurized state) is set to 20 seconds or more. When the holding time increases, the filling rate increases. However, the filling rate reaches a peak even when the holding time becomes 20 seconds or more. In order to increase the strength, the holding time is desirably 20 seconds or more. When the holding time is 20 seconds or more, if the bead width of the adhesive 12 exceeds 40 mm, the filling rate exceeds 100% and the adhesive 12 is wasted. Therefore, the bead width is desirably 40 mm or less.

  The uncured adhesive 12 has a viscosity of 40 Pa · s to 170 Pa · s. Thereby, the spreading | diffusion of the adhesive agent 12 by pressurization can be controlled, and a 80% or more filling rate can be achieved.

  3 to 5 show a metal part 11 that is an inner center pillar that constitutes an inner portion in the vehicle width direction of the center pillar of an automobile. The metal part 11 is formed by pressing a steel plate into a substantially hat-shaped cross section, and includes a pair of welding flanges 11a located at both ends in the front-rear direction, a pair of side walls 11b rising from the pair of welding flanges 11a in the vehicle width direction, and a pair. A bottom wall 11c that connects the side wall 11b in the front-rear direction, and a raised portion 11d that is formed on the bottom wall 11c and protrudes in a groove shape outward in the vehicle width direction. A pair of welding flanges 11a of the metal part 11 are welded to a pair of welding flanges 21a of another metal part 21 that is a center pillar outer having a hat-shaped cross section, and constitute a center pillar having a hollow closed cross section.

  A CFRP reinforcing material 13 having a hat-shaped cross section is bonded to the bottom wall 11c and the raised portion 11d of the metal part 11 with the adhesive 12 described above. The CFRP reinforcing material 13 is obtained by embedding a large number of continuous carbon fibers aligned in the longitudinal direction in a matrix resin, and has a high tensile strength in the longitudinal direction. A pair of upper and lower groove-shaped recesses 11e are formed so as to straddle the bottom wall 11c and the raised portion 11d of the metal part 11 facing both ends in the longitudinal direction of the CFRP reinforcing material 13.

  By manufacturing the CFRP reinforcing material 13 by the autoclave method or the RTM (Resin Transfer Molding) method, it is possible to prevent the generation of voids in the inside thereof and increase the bending strength.

  When the CFRP reinforcing material 13 is bonded to the metal part 11, four clips 22 penetrating the four corners of the CFRP reinforcing material 13 and the bottom wall 11 c of the metal part 11 are attached in a state where the uncured adhesive 12 is compressed. The CFRP reinforcing material 13 is temporarily fixed to the metal part 11 with the clip 22.

  The metal part 11 and the CFRP reinforcing material 13 are bonded to each other with five continuous adhesive surfaces so as to form a hat-shaped cross section, and two bead-shaped adhesives 12 are applied to each of the adhesive surfaces in an arch shape. The The pressing of the CFRP reinforcing material 13 against the metal part 11 is also performed for each bonding surface. The application and compression of the adhesive 12 are performed in the weld zone of the automobile production line, and the subsequent heat curing of the adhesive 12 is performed in the paint zone of the automobile production line.

  Since two bead-shaped adhesives 12 are applied in an arch shape on each bonding surface, no air pockets are generated inside the compressed adhesive 12, and the CFRP reinforcing material 13 for the metal part 11 is formed. Adhesive strength is increased. Further, since the adhesive 12 is compressed for each adhesive surface, even if the CFRP reinforcing material 13 has a non-planar shape such as a hat-like cross section, the adhesive 12 on all the adhesive surfaces can be compressed without any trouble. it can.

  In addition, since the metal part 11 and the CFRP reinforcing material 13 stacked with the uncured adhesive 12 sandwiched therebetween are temporarily fixed by the clip 22, the CFRP reinforcement from the metal part 11 is carried during the transportation from the weld zone to the paint zone of the production line. It is possible to reliably prevent the material 13 from being displaced or dropped.

  Further, when the metal part 11 and the CFRP reinforcing material 13 are heated and then cooled to cure the adhesive 12, the adhesive 12 sandwiched between the metal part 11 having a large coefficient of thermal expansion and the CFRP reinforcing material 13 having a small coefficient of thermal expansion. Is subjected to shear stress, and the shear stress becomes maximum at both ends in the longitudinal direction of the elongated CFRP reinforcing material 13, and the cured adhesive 12 may break and peel at that portion.

  However, according to the present embodiment, the thickness of the adhesive 12 facing both ends in the longitudinal direction of the CFRP reinforcing material 13 is locally increased by the recesses 11e formed in the metal part 11, thereby reducing the shear stress. Thus, breakage and peeling of the adhesive 12 can be prevented in advance.

  Now, when the automobile is subjected to a side collision and a collision load is input to the center pillar, the middle part of the center pillar with the upper and lower ends fixed is curved inward in the vehicle width direction, and the metal part 11 that is the center pillar inner part, A tensile load acts on the CFRP reinforcing material 13 bonded to the metal part 11. At this time, since the carbon continuous fibers of the CFRP reinforcing material 13 are oriented along the longitudinal direction of the metal part 11, the tensile load due to the collision is efficiently supported by the carbon continuous fibers of the CFRP reinforcing material 13, and the center pillar The rigidity and strength can be effectively increased.

Second to fourth embodiments

  FIG. 6A shows a second embodiment of the present invention. In the first embodiment, the adhesive 12 is applied in the form of two arches in order to bond the CFRP reinforcing material 13, but in the second embodiment, the two arched adhesives 12 are applied. In the meantime, another linear adhesive 12 is applied.

  FIG. 6B shows a third embodiment of the present invention. In the first embodiment, the adhesive 12 is applied in the form of two arches in order to bond the CFRP reinforcing material 13, but in the third embodiment, the two arched adhesives 12 are applied. Two arched adhesives 12 are further applied to the outside of the film. The distance between the first arch-shaped adhesive 12 and the added arch-shaped adhesive 12 is set to be small at the central portion in the longitudinal direction and large at both ends in the longitudinal direction. The number of the arched adhesives 12 to be added is not limited to two, and may be three or more.

  FIG. 6C shows a fourth embodiment of the present invention. The fourth embodiment is a combination of the first embodiment and the second embodiment, and one more linear adhesive 12 is applied to the center of the four arched adhesives 12. The That is, the adhesive 12 outside the center line of the total application width of the plurality of adhesives 12 is applied in the arch shape of the present invention.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the body frame structure of an automobile to which the present invention is applied is not limited to the center pillar inner of the embodiment, and may be a front pillar, a rear pillar, a cross member, a roof arch, a side sill, a tire pan, etc. It is effective when applied to a portion that is a closed section member and is subjected to a tensile load when a collision load is input.

  In the embodiment, the CFRP reinforcing material 13 is temporarily fixed to the metal part 11 with the clip 22. However, the temporary fixing means is not limited to the clip 22, and may be a rivet or a self-piercing nut.

11 Metal Parts 12 Adhesive 13 CFRP Reinforcement Material 14 Pressure Machine 18 Pressure Cylinder

Claims (11)

A first step of applying uncured thermosetting adhesive (12) in the form of at least two beads on the surface of the metal part (11), and pressing the CFRP reinforcement (13) against the metal part (11) A second step of pressurizing the adhesive (12) and a third step of heat-curing the adhesive (12) to bond the CFRP reinforcing material (13) to the metal part (11). A method of manufacturing a reinforced metal part,
In the first step, the two bead-shaped adhesives (12) are applied in an arch shape so as to approach each other in the longitudinal central portion and to be separated from each other at both longitudinal ends, In the second step, the two bead-shaped adhesives (12) are sequentially pressed from the longitudinal central portion toward both longitudinal end portions thereof. Production method.   The metal part (11) is a car body frame part of an automobile, and the pressure-sensitive adhesive (12) has a filling rate of 80% to 100%, a maximum protrusion amount of 3.5 mm or less, and a thickness of 0.5 mm. The method for producing a resin-reinforced metal part according to claim 1, wherein the thickness is ± 0.1 mm.   The method for producing a resin-reinforced metal part according to claim 2, wherein the adhesive (12) is applied with a bead width of 40 mm or less and pressed for a holding time of 20 seconds or more.   The method for producing a resin-reinforced metal part according to claim 2 or 3, wherein the uncured adhesive (12) has a viscosity of 40 Pa · s to 170 Pa · s.   The adhesive (12) is an epoxy-based or urethane-based high-viscosity adhesive, and after curing, has an initial elastic modulus with a dumbbell physical property of 1500 MPa or more and a shear strength with an adhesion to the metal part (11) of 20 MPa or more. The method for producing a resin-reinforced metal part according to any one of claims 1 to 4, further comprising:   The method for producing a resin-reinforced metal part according to any one of claims 1 to 5, wherein the CFRP reinforcing material (13) includes carbon continuous fibers oriented in a longitudinal direction.   The said metal component (11) comprises at least one part of a hollow closed cross-section member, and the said CFRP reinforcing material (13) is adhere | attached on the surface where a tensile load acts. The manufacturing method of the resin reinforced metal component of any one of these.   8. The adhesive according to claim 1, wherein the adhesive (12) is heat-cured in a state where the CFRP reinforcing material (13) is temporarily fixed to the metal part (11). Manufacturing method for resin-reinforced metal parts.   The method for manufacturing a resin-reinforced metal part according to any one of claims 1 to 8, wherein the CFRP reinforcing material (13) is manufactured by an autoclave method or an RTM method.   The said 2nd process is performed with respect to each surface, when the said metal component (11) is provided with several surface which mutually cross | intersects, The any one of Claims 1-9 characterized by the above-mentioned. Manufacturing method for resin-reinforced metal parts.   The second step uses a pressurizer (14) in which a plurality of pressurization cylinders (18) for pressing the CFRP reinforcing material (13) against the metal part (11) are arranged in a straight line, and the pressurization on the center side is performed. The method for producing a resin-reinforced metal part according to any one of claims 1 to 10, wherein the pressure cylinders (18) on both ends are sequentially operated from the cylinder (18). .