JP2018061979A - Pipe manufacturing method and press device used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely and smoothly engage a projection and a recess in a pipe manufacturing method in which steel sheet is formed into a circular shape and, at the same time, the projection and the recess, formed at both side edges of the steel sheet, are engaged.SOLUTION: In a pipe manufacturing method including forming a steel sheet into a circular shape and, at the same time, engaging a projection 11 and a recess 12 formed in combination at both side edges of the steel sheet comprises: placing an external surface along a half lower die forming-surface 41 and a half upper die forming-surface 51 of a post-process lower press die 4 and a post-process upper press die 5, respectively; placing a mandrel 8 along an internal surface and forming the steel sheet into a circular shape; butting, in advance, both the side edges of the steel sheet except the projection 11 and the recess 12; placing a block forming-surface 531 of an engagement block 53 against the external surface of the projection 11 thereafter; and pushing it into the recess 12 from outside so as to bring the internal surface of the projection 11 into contact with the mandrel 8, thereby engaging the projection 11 and the recess 12.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a pipe manufacturing method for manufacturing a pipe by rolling a steel plate, and a press device used therefor.

  The pipe constituting the silencer is manufactured by rolling a steel plate with the aim of reducing the manufacturing cost. Pipes made by rolling steel plates were subjected to TIG welding and seaming at the ends of both sides. However, both of them bring about an increase in manufacturing cost because work after manufacturing of the pipe is required. In addition, the TIG welding may require modification of the shape of the pipe against thermal deformation, and the seaming process requires a steel plate that is larger than the width of the folded side edge, leading to an increase in material cost. Then, the pipe which joins both side edges simultaneously with rolling a steel plate is proposed (patent document 1).

  Patent document 1 assigns and forms the circular protrusion or recessed part which becomes a pair on each both-sides edge of a steel plate, when the both-side edges are faced | matched, the said protrusion and a recessed part are fitted, and the said protruding piece to the circumferential direction And a pipe for engaging the recess. Since the projecting piece and the concave portion approach each other from the circumferential direction, they cannot be fitted well. In Patent Document 1, the vicinity of the base where the concave portion is constricted (both edges of the neck portion) is opened upward, and the projecting piece is fitted into the concave portion from the circumferential direction. A joining method is proposed in which the vicinity of the base of the concave portion is inserted near the base of the protruding piece (Patent Document 1, Claims, page 2, upper right column, lines 5 to 9).

JP 60-046831 A

  The pipe manufacturing method for fitting a pair of protruding pieces and recesses formed on both side edges of the steel plate at the same time as rounding the steel plate does not require post-process TIG welding or shape correction, and thus does not increase the manufacturing cost. Since the pipe for fitting the projecting piece and the recess firmly joins both side edges of the steel plate, as disclosed in Patent Document 1, a configuration in which the projecting piece and the recess having the roots constricted is preferably fitted. It is also understood that in order to successfully fit the projecting piece and the concave portion with the roots constricted, for example, as disclosed in Patent Document 1, a device such as raising the vicinity of the base of the concave portion is required.

  However, Patent Document 1 does not disclose a method of raising the vicinity of the root of the recess for fitting the protrusion and the recess. For example, if the pre-step of raising the vicinity of the root of the concave portion is before press forming that rounds the steel plate, the raised portion may be in the way and press forming with a press die may not be possible. Further, Patent Document 1 discloses a specific method of processing in which the protruding piece is fitted into the concave portion, and then the standing state near the base of the concave portion is canceled and the protruding piece is bitten near the base of the protruding piece. Absent. Although press forming that rounds a steel plate may be used, a special press die should be required for this purpose, but there is no indication or illustration of the press die.

  Therefore, in the pipe manufacturing method for fitting the pair of projecting pieces and recesses formed on both side edges of the steel plate at the same time as rolling the steel sheet, the projecting pieces and the recesses are recessed even if each of the roots is constricted. Pipe manufacturing method and this for the purpose of fitting the projecting piece and the concave portion without difficulty by only pressing using a press die without requiring a pre-process such as raising the vicinity of the root of The press device used for the test was examined.

  What has been developed as a result of the study, in the pipe manufacturing method of fitting a pair of protruding pieces and recesses formed on both side edges of the steel plate at the same time as rounding the steel plate, the outer surface is attached to the mold surface of the press die, The mandrel is directed to the inner surface, the steel plate is rounded, the both side edges of the steel plate excluding the projecting piece and the recess are brought into contact with each other in advance, and then the block forming surface of the fitting block is applied to the outer surface of the projecting piece. The pipe manufacturing method is characterized in that the projecting piece and the concave portion are fitted by being pushed into the concave portion from the outside so that the inner surface of the inner surface contacts the mandrel. The pipe manufacturing method of the present invention does not limit the shape of the protruding piece and the recessed portion formed on both side edges of the steel plate, but is particularly suitable for the protruding piece and the recessed portion having a shape with a narrow base.

  In the pipe manufacturing method of the present invention, first, both side edges of the steel sheet are butted together except for the projecting pieces and the recesses. At this time, the projecting piece extends in a tangential direction from the side edge on which the projecting piece is provided, and is located on the outside (radius outside of the pipe) with respect to the recess. The fitting block presses the block forming surface against the outer surface of the projecting piece, and sandwiches it with the mandrel, thereby fitting the projecting piece into the recess and continuing to the peripheral surface of the previously formed pipe. Is molded. Since the projecting piece is pushed into the recess from the outside, both can be fitted regardless of the shape of the projecting piece and the recess.

  In the pipe manufacturing method of the present invention, a cylindrical intermediate product in which a press die is rounded a steel plate is formed in advance, and then the projecting piece is fitted into the recess by the fitting block. From now on, if the intermediate product can be supported stably, after the intermediate product is molded, the press die is removed, and the block molding surface of the mating block is placed on the outer surface of the projecting piece while the mandrel is supported from the inside on both sides. It can also be pressed. However, in the press die, it is better to press the block forming surface of the mating block against the outer surface of the protruding piece while holding the mold forming surface on the outer surface of the steel plate with both side edges butted between the press die and the mandrel. The product can be stably supported, which is preferable.

  More specifically, the press die is a pair of upper press die and lower press die having a semicircular arc-shaped upper die forming surface and a lower die forming surface, and both side edges of the steel plate are connected to the upper die forming surface of the upper press die. The fitting block is pressed against the outer surface of the protruding piece through the through hole provided in the upper press die. In the intermediate product, the upper press die and the lower press die are formed by rolling a steel plate so that the projecting pieces and the recesses are located in the range of the through holes provided in the upper press die. Thereby, the block molding surface of the fitting block can be pressed against the outer surface of the protruding piece of the intermediate product that is stably supported by being sandwiched between the upper press die and the lower press die. The through-hole also serves as a guide for specifying the pushing direction of the fitting block when the block forming surface of the fitting block is pressed against the outer surface of the intermediate projecting piece.

  The press die used in the pipe manufacturing method of the present invention is as follows. That is, in a press device used in a pipe manufacturing method for fitting a pair of protruding pieces and recesses formed on both side edges of the steel plate at the same time as rolling the steel plate, a lower press die having a lower mold forming surface with a semicircular cross section An upper press die having an upper die forming surface having a semicircular cross section that is paired with the lower die forming surface of the lower press die, and having a through-hole opened in a part of the upper die forming surface; The upper press mold includes a fitting block having a block molding surface continuous with the upper mold molding surface, the lower press die is fixed in position with the lower mold molding surface facing upward, and the upper press die is the upper die With the molding surface facing down and facing the lower mold molding surface of the lower press mold, it is supported by the ram via an elastic connecting member, and the fitting block is above the upper mold molding surface of the upper press mold The block forming surface positioned at the ram was supported by the ram with the surface facing down. A pressing device used in pipe manufacturing method comprising and.

  The press apparatus of the present invention uses a mandrel as in the prior art. The mandrel is placed on the inner surface of the steel plate attached to the lower mold forming surface of the lower press die, and both side edges of the steel plate placed on the upper surface are sandwiched with the upper mold forming surface of the upper press die. In the press apparatus of the present invention, when the ram is lowered, the upper press die and the fitting block are lowered together. First, the upper press die first presses the upper mold forming surface against the steel plate and rounds the steel plate. Then, when the lowering of the upper press die is blocked by the lower press die, the ram is lowered while compressing the elastic member to lower only the fitting block, and the block molding surface of the fitting block is brought to the outer surface of the projecting piece. Press. The elastic member may be a member or device that elastically deforms (a member or device that contracts if there is a load and returns to its original state when the load is removed), and examples thereof include a gas spring and a coil spring.

  Since the fitting block only needs to be able to pass through the through hole provided in the upper press die, the cross section may be smaller than the cross section of the through hole. However, if the upper press die is provided with a through-hole having a cross-sectional shape excluding a circular shape, and the fitting block has the same cross-sectional shape as the through-hole, and the side surface is in sliding contact with the inner surface of the through-hole, the through-hole Can be used as a guide for specifying the downward trajectory of the fitting block, so that the downward trajectory of the fitting block is stabilized. In addition, since the inner surface or corner of the through hole and the side surface or corner of the fitting block are engaged, there is no possibility that the fitting block rotates, and the upper molding surface of the upper press die and the block molding surface of the fitting block Will not shift. The “cross-sectional shape excluding a circular shape” means a cross-sectional shape having inner surfaces, side surfaces, and corner portions that form a pair of a through hole and a fitting block, and examples thereof include a square cross section.

  When manufacturing a pipe fitted with a pair of protruding pieces and recesses formed on both side edges of the steel sheet by the pipe manufacturing method of the present invention, a press die was used without performing additional processing on the protruding pieces and recesses. The protrusions and the recesses can be securely and reliably fitted by pressing alone. In particular, press forming that manufactures a pipe from a steel plate without additional processing such as raising the vicinity of the root of the recess as seen in Patent Document 1, even in a projecting piece and recess having a base that can be firmly fitted. The projecting piece and the recess can be fitted with each other, and the manufacturing cost is excellent.

  When the press mold is pressed against the outer surface of the projecting piece while the mold forming surface is attached to the outer surface of the steel sheet with both side edges abutted against each other, the molding of the steel plate by the press mold and the fitting block It is possible to press-mold the protrusions and the recesses in a continuous manner. Specifically, when the press die is composed of an upper press die and a lower press die, and the block forming surface of the fitting block is pressed against the outer surface of the protruding piece through a through hole provided in the upper press die, it will be described later. The advantage is that the upper press die and the fitting block can be lowered with the same ram, or the fitting block can be lowered without rotating with the through hole as a guide, at the heart of the pressing device.

  The press device of the present invention having a lower press die, an upper press die, and a fitting block has a configuration in which the fitting block is lowered through a through hole provided in the upper press die, and the rams of the upper press die and the fitting block are arranged. While being common, a step-by-step procedure for lowering the upper press die in advance and subsequently lowering the fitting block can be performed, and the pipe manufacturing method of the present invention can be carried out by a single press molding. In addition, if the through hole provided in the upper press mold has a cross-sectional shape excluding a circle and the fitting block has the same cross-sectional shape, the through-hole serves as a guide and the fitting block is stably lowered without rotating. It is possible to fit the projecting piece and the recessed portion by press molding cleanly and surely.

It is a perspective view showing an example of the steel plate provided to the pipe manufacturing method of the present invention. It is a perspective view showing the manufacturing process of the steel plate of this example. It is a perspective view showing the preparatory step of the pre-process which bends a steel plate in a U-shaped section. It is a perspective view showing the stage which created the U-shaped cross section intermediate product by the previous process. It is a perspective view showing a U-shaped cross-section intermediate product. It is a perspective view showing the preparatory step of the post-process which bends a U-shaped cross-section intermediate product into a circular section. It is a perspective view showing the press die on a back process used for a back process. It is a perspective view showing the step which produced the cylindrical intermediate product which the protrusion and the recessed part have not fitted by the post process. It is a partial fracture front view showing the stage which created the cylindrical intermediate product which the projection piece and the crevice did not fit by a back process (breaking a press die on a back process). It is a partial abbreviation top view showing the stage which produced the cylindrical intermediate product which the projection piece and the crevice have not fitted by the back process (the press die on a back process is omitted). It is a perspective view showing the stage which pushed the protrusion into the recessed part with the fitting block, and created the pipe. It is a partial fracture front view showing the stage which pushed the projection piece into the crevice by the fitting block, and created the pipe (the press die on a back process is fractured). It is a perspective view showing the completed pipe. It is a perspective view showing an example of the press apparatus of this invention which produces a pipe by a single process.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the pipe manufacturing method of the present invention, when the steel plate 1 (see FIG. 1) provided with a pair of protruding pieces 11 and concave portions 12 on both side edges is rolled and both side edges are butted, the protruding pieces 11 and the concave portions 12 are fitted. Thus, the pipe 16 (see FIG. 13) is manufactured. As shown in FIG. 2, the steel plate 1 is separated from the original plate 13 by cutting the fed original plate 13 along a cutting line including the outer edge of the protruding piece 11 (the inner edge of the recess 12). As a result, the steel sheet 1 inevitably includes the protruding pieces 11 and the recesses 12 which are paired on both side edges, and can eliminate the generation of scraps to be discarded. When a hole is provided in the pipe 16, it is opened in the step of separating from the original plate 13 or the step after separation.

  The steel plate 1 of the present example is a protruding piece 11 and a recessed portion 12 having a shape in which the base is constricted. The projecting piece 11 and the recess 12 having a shape with a narrow base are difficult to separate in the surface direction (the tangential direction of the circumferential surface of the pipe 16) when fitted, and the pipe 16 can be stably maintained in shape. However, the fitting that is difficult to separate means that it is difficult to fit the protrusion 11 and the recess 12 from the surface direction. Since the pipe manufacturing method of the present invention is pushed into the concave portion 12 from the outside in the plane orthogonal direction (the radial direction outer side of the pipe 16), even the projecting piece 11 and the concave portion 12 having a narrowed root can be fitted.

  This example shows two presses, a pre-process for making a U-shaped intermediate product 14 (see FIGS. 4 to 6) and a post-process for making a cylindrical intermediate product 15 (see FIGS. 8 to 10) and a pipe 16. It is a pipe manufacturing method that undergoes processing. The pre-process pressing apparatus includes a pre-process lower press die 2 (see FIG. 3) and a pre-process lower press die 3 (see FIG. 4). The post-process pressing apparatus includes a post-process lower press die 4 (see FIG. 6) and a pre-process lower press die 5 (see FIG. 7). The pre-process and post-process press apparatuses are usually installed side by side, and the pre-process and post-process are performed simultaneously. In addition, the post-process pressing apparatus uses a mandrel 8 having a pair of side surfaces equal to the inner surface of the pipe 16 (see FIG. 6).

  In the pre-process, the U-shaped intermediate product 14 is created by sandwiching the steel plate 1 between the pre-process lower press die 2 and the pre-process upper press die 3. The pre-process lower press die 2 is a U-shaped lower die composed of an arc-shaped cross section that follows the outer surface of the U-shaped cross-section intermediate product 14 and a pair of left and right linear cross sections that extend upward as a tangent to the arc-shaped cross section. A molding surface 21 is provided on the upper surface side (see FIG. 3), and the U-shaped lower mold molding surface 21 is positioned upward and fixed to a frame (not shown) of the press device.

  In the pipe manufacturing method according to the present invention, the projecting piece 11 and the recessed portion 12 are sandwiched between the fitting block 53 and the mandrel 8 in the final stage (the subsequent stage of the present example) (see FIG. 12). It is necessary to round the steel plate 1 so that is located at a predetermined position. Therefore, in order to specify which part of the steel plate 1 is rounded to make the U-shaped cross-section intermediate product 14, when the steel plate 1 is placed on the lower press die 2 in the previous process, the U-shaped lower mold forming surface 21 is The position of the steel plate 1 is specified.

  In this example, as shown in FIG. 3, a pair of left and right front process left and right positioning blocks 22 and 22 are applied to both side edges of the steel plate 1 (left rear and right front in FIG. 3). The left and right center of the letter-shaped lower mold forming surface 21 and the left and right center of the steel plate 1 are aligned. The left-right center of the steel plate 1 is the middle of the distance between both side edges provided with the protruding pieces 11 and the recessed portions 12. Further, the rear-end edge of the U-shaped lower mold forming surface 21 and the back-side edge of the steel plate 1 are placed by applying a pre-process length direction positioning block 23 to the rear edge of the steel plate 1 (right back in FIG. 3). Match. When the U-shaped lower mold forming surface 21 is longer than the steel plate 1, the pre-process length direction positioning block 23 may be omitted.

  In the pre-process, after the positioning of the steel plate 1 with respect to the U-shaped lower mold forming surface 21, as shown in FIG. 4, the pre-process upper press die 3 is lowered, and the pre-process lower press die 2 and the pre-process upper The steel sheet 1 is sandwiched between the press dies 3 and rolled. The pre-process upper press die 3 has an outer surface similar to the U-shaped lower mold forming surface 21 of the pre-process lower press die 2 and a U-shaped upper mold forming surface 31 on the lower surface side. It is attached to the ram 32 for the pre-process of the press device in a posture with the molding surface 31 facing downward.

  Thus, the steel plate 1 that has undergone the preceding process becomes a U-shaped intermediate product 14 as seen in FIG. The U-shaped cross-sectional intermediate product 14 corresponds to a lower half obtained by dividing the pipe 16 in half, and has a U-shaped cross section in which the projecting pieces 11 and the recesses 12 face upward. The previous process up to this point is no different from the conventional pipe manufacturing method in which a pipe is made from a steel plate that does not have protrusions and recesses (the conventional U-shaped intermediate product has an outer shape without protrusions 11 and recesses 12). ). The features of the present invention appear in the post-process.

  The post-process creates a cylindrical intermediate product 15 by sandwiching the U-shaped cross-section intermediate product 14 between the post-process lower press die 4 and the post-process upper press die 5, and further presses the projecting piece 11 with the fitting block 8. Fits 12 and builds pipe 16. The post-process lower press die 4 has a half-section composed of an arc-shaped cross section (equal to the arc-shaped section of the U-shaped cross-section intermediate product 14 or the cylindrical intermediate product 15) following the outer surface of the lower half of the pipe 16 divided in half. A lower mold forming surface 41 is provided on the upper surface side (see FIG. 6), and the position is fixed to a frame (not shown) of the press apparatus with the half-shaped lower mold forming surface 41 opened upward.

  In the post-process, the position of the U-shaped intermediate product 14 with respect to the half-shaped lower mold forming surface 41 is specified as in the pre-process. In this example, the curved portion of the U-shaped cross-section intermediate product 14 is sandwiched between the half-shaped lower mold forming surface 41 and the outer surface of the mandrel 8, so that the left and right sides of the half-shaped lower mold forming surface 41 of the lower press die 4 in the post-process are The center and the left and right center of the steel plate 1 are aligned. The left-right center of the U-shaped cross-section intermediate product 14 is the middle of the distance between both side edges provided with the projecting piece 11 and the recess 12. Further, a rear process length direction positioning block 43 is applied to the rear edge of the U-shaped intermediate product 14 (right rear in FIG. 6) and the rear edge of the half-shaped lower mold forming surface 41 and the rear side of the steel plate 1. Match the edges.

  In this way, the left-right direction and the front-rear direction of the U-shaped intermediate product 14 are positioned with respect to the half-shaped lower mold forming surface 41. As a result, when the U-shaped intermediate product 14 is deformed by press working in the first stage of the post-process, the fitting positions of the through hole 511, the projecting piece 11 and the recess 12 of the post-process upper press die 5 described later are made coincident. In this example, the block forming surface 531 of the fitting block 53 is passed through the through hole 511 of the post-process upper press die 5 while the cylindrical intermediate product 15 is held by the post-process lower press die 4 and the post-process upper press die 5. Is pressed against the outer surface of the projecting piece 11, it is important to match the through hole 511 of the press die 5 with the fitting position of the projecting piece 11 and the recess 12 in the post-process.

  In the post-process, after the positioning of the steel plate 1 with respect to the half-shaped lower mold forming surface 41 is finished, the post-process upper press die 5 is lowered, and the post-process lower press die 4 and the post-process upper press die 5 are in the middle of the U-shaped cross section. Roll 14 while sandwiching product 14. The pipe manufacturing method of the present invention is composed of two-stage press working in which post-processes are continuous. The front press process creates a cylindrical intermediate product 15 from the U-shaped intermediate product 14. Then, the subsequent press working of the subsequent stage creates the pipe 16 from the cylindrical intermediate product 15. The pre-stage and the post-stage press work are continuously performed only by lowering the press die 5 in the post-process.

  As shown in FIG. 7, the post-process upper press die 5 has a halved upper mold forming surface 51 on the lower surface side formed of an arc-shaped cross section that follows the outer surface of the upper half of the pipe 16 that is halved. Through holes 511 and 511 are provided at two locations in the front-rear direction (the direction connecting the left front side and the right back side in FIG. 7) of the half-shaped upper mold forming surface 51. The through-hole 511 has a square cross section in which two opposite sides are aligned in the extending direction and the extending orthogonal direction of the halved upper mold forming surface 51, and the halved upper mold is formed from the upper surface of the press die 5 in the post process. It penetrates to surface 51. The fitting block 53 is a prism having a cross section equal to the through-hole 511, and has a block forming surface 531 formed of a peripheral surface having an arcuate cross section continuous with the half-shaped upper mold forming surface 51 on the lower surface.

  The post-process upper press die 5 is attached to the press device post-process ram 52 via an elastic member (in this example, a coil spring) 521 with the halved upper mold forming surface 51 facing downward. Further, the fitting block 53 faces the block forming surface 531 downward and faces the position above the half-shaped upper mold forming surface 51 of the post-process upper press die 5 in the post-process upper press. It is inserted through the through hole 511 of the mold 5 and directly attached to the ram 52 for the post process of the press device. The block forming surface 531 of the fitting block 53 does not contact the U-shaped intermediate product 14 even when the half-shaped upper mold forming surface 51 of the press die 5 in the post-process contacts the U-shaped intermediate product 14.

  As shown in FIG. 8, the first stage of the post-process is the arc-shaped side surface of the mandrel 8 on the inner surface of the U-shaped intermediate product 14 positioned with respect to the half-shaped lower mold forming surface 41 of the post-process lower press die 4. The ram 52 for the post process is lowered while being directed, and both side edges of the U-shaped intermediate product 14 are rounded by the half-shaped upper mold forming surface 51 of the press die 5 on the post process, A cylindrical intermediate product 15 is produced. At this time, the U-shaped intermediate product 14 and the cylindrical intermediate product 15 are in contact with only the half-shaped upper mold forming surface 51 of the press die 5 in the post-process, and are in contact with the block forming surface 531 of the fitting block 53. Absent.

  Further, even when the cylindrical intermediate product 15 is produced, as shown in FIGS. 9 and 10, the range of the through hole 511 is not deformed by pressing, and both the projecting piece 11 and the recess 12 are cylindrical. The intermediate product 15 remains in a state of protruding in the circumferential tangent direction. The projecting piece 11 and the recess 12 are formed in the range of the through hole 511 by positioning the U-shaped cross-sectional intermediate product 14 with respect to the half-shaped lower mold forming surface 41 of the post-process lower press die 4 at the beginning of the post-process. It is in. Here, if the size of the through hole 511 is about 2 to 3 times the size of the projecting piece 11, even if the positioning of the U-shaped intermediate product 14 is deviated, the projecting piece 11 and the recess 12 are always provided in the through hole. It is in the range of 511.

  When the post-process ram 52 is further lowered from the state where the cylindrical intermediate product 15 is thus produced, the post-process upper press die 5 whose lowering is prevented by the post-process lower press die 4 and the mandrel 8 becomes the elastic member 53. During compression, the fitting block 53 descends and starts pushing the protruding piece 11 by the block molding surface 531. Since the fitting block 53 has an outer shape equal to the cross-sectional shape of the through-hole 511, the fitting block 53 descends straight without rotating. 11 and 12, when the projecting piece 11 is fitted into the recess 12 and sandwiched between the fitting block 53 and the mandrel 8, the press work is completed, and the pipe 16 (see FIG. 13) Is completed. The former stage and the latter stage of the subsequent process are only one press work and are continuous.

  For example, as shown in FIG. 14, the present invention can also be applied to single-step pressing by a single-step lower press die 6 and a single-step upper press die 7. The single-step lower press die 6 has a half-like lower die forming surface 61 formed on an upper surface side, which is formed by an arc-shaped cross section following the outer surface of the lower half of the pipe 16 that is half-divided. The position is fixed to a frame (not shown) of the pressing device with the face 61 opened upward. The half-shaped lower mold forming surface 61 is open so that the steel sheet is formed into a V shape (the interval between the upper edges is wider than the outer diameter of the pipe 16). Further, the upper surface of the single-process lower press die 6 is provided with a transfer inclined surface 62 that receives the guide inclined surface 74 of the single-process upper press die 7 with a downward slope from the half-shaped lower mold forming surface 61.

  The single-step upper press die 7 has a halved upper mold forming surface 71 formed on an underside formed of an arc-shaped cross section following the outer surface of the upper half of the pipe 16 halved. Through holes 511 and 511 are provided at two locations in the front-rear direction of the surface 71 (the direction connecting the left front side and the right back side in FIG. 14). The lower surface of the single-step upper press die 7 is provided with a guide inclined surface 74 that is inclined downward from the half-shaped upper die forming surface 71. The through-hole 711 has a square cross section in which two opposite sides are aligned in the extending direction and the extending orthogonal direction of the half-shaped upper mold forming surface 71, and the half-shaped upper mold is formed from the upper surface of the single press upper die 7. It penetrates to surface 71. The fitting block 73 is a rectangular column having a cross section equal to the through hole 711 and has a block forming surface 731 formed on a lower surface formed of a peripheral surface having an arcuate cross section continuous with the half-shaped upper mold forming surface 71.

  The single-process upper press die 7 is attached to the post-process ram 72 of the press device via an elastic member (in this example, a coil spring) 721 with the half-shaped upper mold forming surface 71 facing downward. Further, the fitting block 73 has the block forming surface 531 facing downward and the single step upper press in a posture facing the position above the half-shaped upper mold forming surface 71 of the single step upper press die 7. The die 7 is inserted through the through-hole 711 and directly attached to the ram 72 for the post-process of the press device. The block forming surface 531 of the fitting block 73 does not come into contact with the U-shaped intermediate product 17 even when the half-shaped upper mold forming surface 71 of the press die 7 in the single process contacts the U-shaped intermediate product 14.

  In the single process, after the positioning of the steel plate with respect to the half-shaped lower mold forming surface 61 is finished, first, the mandrel 8 is pressed from above to make a U-shaped intermediate product 17 and then the single process upper press die 7 is lowered. The both side edges of the U-shaped cross-sectional intermediate product 17 are guided by the guide inclined surface 74 and bent, so that the U-shaped cross-sectional intermediate product 17 is sandwiched between the single-process lower press die 6 and the single-process upper press die 7 and rolled. Go. At this time, the U-shaped intermediate product 17 is in contact with only the half-shaped upper mold forming surface 71 of the upper press die 7 in a single process, and is not in contact with the block forming surface 731 of the fitting block 73 (see FIG. 9). .

  If the single-process ram 72 is further lowered from the state in which the U-shaped intermediate product 17 is created in this way, the single-process upper press die 7 that is prevented from being lowered by the single-process lower press die 6 and the mandrel 8 is an elastic member. While compressing 73, the fitting block 73 descends and starts pushing the protruding piece 11 by the block forming surface 731. Then, when the projecting piece 11 is fitted into the concave portion 12 (see FIGS. 11 and 12) and sandwiched between the fitting block 73 and the mandrel 8, the press work is completed and the pipe 16 (see FIG. 13) is completed. .

1 Steel plate
11 Projection
12 Recess
13 Original plate
16 pipes
17 U-shaped intermediate product 2 Pre-process lower press die
21 U-shaped lower mold molding surface 3 Press mold in the previous process
31 U-shaped upper mold surface
32 Pre-process ram 4 Post-process lower press die
41 Half-shaped lower mold forming surface 5 Post-process press die
51 Upper half mold surface
511 Through hole
52 Post process ram
521 Elastic member
53 Mating block
531 Block forming surface 6 Single-process lower press die
61 Half-divided lower mold forming surface 7
71 Half-shaped upper mold surface
711 Through hole
72 Single process ram
721 Elastic member
73 Mating block 8 Mandrel

Claims (5)

In the pipe manufacturing method of fitting a pair of protruding pieces and recesses formed on both side edges of the steel plate simultaneously with rounding the steel plate,
The outer surface is attached to the mold surface of the press mold, the mandrel is directed to the inner surface, the steel plate is rounded, the two edges of the steel plate excluding the projecting piece and the recess are butted together, and then fitted to the outer surface of the projecting piece A pipe manufacturing method, wherein the projecting piece and the recess are fitted by pressing the block forming surface of the block and pressing the projecting piece into the recess from the outside so that the inner surface of the projecting piece contacts the mandrel. 2. The pipe manufacturing method according to claim 1, wherein the press die presses the block forming surface of the fitting block against the outer surface of the protruding piece while the die forming surface is attached to the outer surface of the steel plate with both side edges abutted. The press mold is a pair of upper press mold and lower press mold having a semicircular arc-shaped upper mold forming surface and lower mold forming surface. Both side edges of the steel plate are butted within the range of the upper mold forming surface of the upper press mold, and the upper press The pipe manufacturing method according to claim 1, wherein the fitting block is pressed against the outer surface of the protruding piece through a through hole provided in the mold. In the press device used in the pipe manufacturing method for fitting the protruding pieces and the recesses that are formed on the both side edges of the steel plate at the same time as rolling the steel plate,
A lower press die having a lower die forming surface with a semicircular cross section;
An upper press die having an upper mold forming surface with a semicircular cross section that is paired with the lower mold forming surface of the lower press die, and having a through-hole opened in a part of the previous mold forming surface;
A fitting block having a block molding surface continuous with the upper mold molding surface of the upper press die,
The lower press die is fixed in position with the lower die forming surface facing up,
The upper press die is supported by the ram through the elastic connecting member in a state where the upper mold forming surface faces downward and faces the lower mold forming surface of the lower press die,
A press apparatus used in a pipe manufacturing method, wherein the fitting block is supported by a ram with a block forming surface positioned above the upper mold forming surface of the upper press die facing downward. The upper press die is provided with a through-hole having a cross-sectional shape excluding a circular shape,
The press apparatus used for the pipe manufacturing method according to claim 4, wherein the fitting block has the same cross-sectional shape as the through-hole and the side surface is slidably contacted with the inner surface of the through-hole.

Images