JP2018030145A - Manufacturing method of metal cylinder body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a new metal cylinder body capable of highly accurately setting inner and outer diameters of the metal cylinder body when manufacturing the metal cylinder body according to press bending working of a metal blank sheet.SOLUTION: A manufacturing method of a metal cylinder body 10 includes: a process (a) of performing press working of a metal blank sheet 12 of a flat plate shape to obtain a belt-like body 20 provided with overlapped parts 14a, 14b on both ends thereof; a process (b) of forming a concave part 24 and a convex part 26 which are engaged to each other on the overlapped parts 14a, 14b at the same time while overlapping the overlapped parts 14a, 14b and retaining the belt-like body 20 into a target diameter size; and a process (c) of joining the overlapped parts 14a, 14b of the belt-like body 20 by abutting welding electrodes 32, 34 on an engaged part of the concave part 24 and the convex part 26, pushing a metal core 38 of the welding electrode 32 against the convex part 26 and performing welding while engaging the concave part 24 and the convex part 26 to each other and retaining the belt-like body 20 into the target diameter size, the welding electrode 32 being provided with the metal core 38 which is harder than a circumference 36 on a tip center part.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method of manufacturing a metal cylinder used for fluid conduits, and more particularly to a method of manufacturing a metal cylinder formed by pressing a base plate.

  2. Description of the Related Art Conventionally, there are metal cylinders that require high accuracy with respect to an inner peripheral surface and an outer peripheral surface, such as fluid conduits that constitute an intake passage and an exhaust passage of an internal combustion engine. Such a metal cylinder is generally cold drawn as shown in, for example, Japanese Patent Application Laid-Open No. 2003-112218 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2006-299300 (Patent Document 2). The pipe material obtained by processing is manufactured by cutting at an appropriate length.

  By the way, when manufacturing the target metal cylinder from the pipe material obtained by cold drawing, depending on the required shape of the metal cylinder, it may be troublesome and the manufacturing cost may increase. There is. For example, when edge processing for forming an inclined surface such as a C-plane or an R-plane is required for the end edge in the length direction of the metal cylinder, a metal cylinder having a target length is used. After cutting out, it was necessary to perform edge processing by turning or the like, and the yield was also poor.

  Then, in view of such a problem, this inventor examined the manufacturing of the target metal cylinder body by bending a base plate by press work and welding the both ends of a bending direction.

  However, if both ends in the bending direction of the bent base plate are butted and welded, the weld bead reduces the dimensional accuracy of the inner and outer peripheral surfaces of the metal cylinder, and satisfies the required accuracy such as dimensions and shape. It was difficult to realize a metal cylinder. In addition, the bent base plate may be difficult to secure a stable welding position by a metal spring back, and in that case, it is difficult to achieve the required diameter with sufficient accuracy.

JP 2003-112218 A JP 2006-299300 A

  The present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is that both ends in the bending direction of the bent metal base plate are produced when the metal cylinder is manufactured by press bending of the metal base plate. It is possible to set the inner and outer diameters of the metal cylinder with high accuracy by welding the parts at appropriate positions, and to prevent deterioration of the dimensional accuracy of the inner and outer peripheral surfaces of the metal cylinder due to the weld beads. An object of the present invention is to provide a novel method for manufacturing a metal cylinder.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible.

  That is, the first aspect of the present invention is a method for manufacturing a metal cylinder, and (a) a strip-shaped metal base plate is bent and provided with overlapping portions for connection at both ends in the bending direction. A step of obtaining a body, and (b) a concave portion and a convex portion that are engaged with each other between the overlapping surfaces at both ends while the overlapping portions at both ends of the belt-like body are overlapped and held in a state of a desired diameter. And (c) a composite electrode in which at least one of a pair of welding electrodes that are abutted across the material to be welded is provided with a metal core that is harder than the periphery relative to the center of the tip. The pair of welding electrodes with respect to the engaging portion of the concave portion and the convex portion in a state where the concave portion and the convex portion are engaged with each other to hold the belt-like body at a target diameter. And the metal of one welding electrode made into the composite electrode By performing welding by pressing the convex portion, and a step of fixedly joining the overlapping portions of the two ends of the belt-shaped member, characterized in that it comprises.

  According to the manufacturing method of the metal cylinder according to the first aspect as described above, the metal cylinder is manufactured at low cost by bending the flat metal base plate and welding and connecting both ends to each other. be able to. In particular, when chamfering or the like is required for the corners at both ends of the metal cylinder in the axial direction, chamfering or the like can be performed in advance on the corners of the flat metal base plate. Therefore, processing becomes easy.

  Further, a connecting overlapping portion is provided at both ends of the band-shaped body formed by processing the metal base plate, and the concave and convex portions are formed with respect to the overlapping portions at both ends in a state where the band-shaped body has a desired diameter. By forming each of these simultaneously, the belt-like body can be held at a desired diameter by engagement of the concave and convex portions. Thereby, a metal cylinder can be easily and stably formed with the target diameter by connecting the overlapping portions at both ends of the belt-like body by welding.

  Moreover, as compared with the case where the concave portion and the convex portion are separately formed on the overlapping portions at both ends, the positioning of the overlapping portion by the engagement of the concave portion and the convex portion can be realized with higher accuracy, and the concave portion and the convex portion can be realized. By being formed in a pre-engaged state, poor engagement due to dimensional errors between the concave and convex portions can be avoided.

  Further, in a state where the overlapping portions at both ends of the belt-like body are overlapped with each other, a pair of welding electrodes are brought into contact with the engaging portions of the concave portion and the convex portion in the overlapping portion, and the overlapping portion is welded in the thickness direction. As compared with the case where both ends of the belt-like body are joined to each other in the circumferential direction and joined by welding, the accuracy of the inner and outer diameters by the weld bead is prevented from being reduced, and the desired inner and outer diameter dimensions are obtained. The metal cylinder can be obtained with high accuracy.

  In addition, a pair of welding electrodes used when joining the overlapping portions at both ends of the belt-like body by welding is pressed against at least the convex portion, but a metal core that is harder than the surroundings with respect to the center portion of the tip. It is set as the composite electrode provided. As a result, wear at the center of the tip of the welding electrode due to pressing against the convex portion is reduced, and the durability of the welding electrode is improved.

  According to a second aspect of the present invention, in the method for manufacturing a metal cylinder described in the first aspect, the one of the overlapping portions of the belt-like body is thinned from the inner peripheral side, and the other The overlapping portion is made thin from the outer peripheral side.

  According to the second aspect, in the portion where the overlapping portions are overlapped with each other in the circumferential direction of the metal cylinder, the thickness dimension of the metal cylinder is prevented from being remarkably increased, and the metal cylinder It can suppress that the precision of an internal diameter dimension and an external diameter dimension falls partially in the circumferential direction.

  According to a third aspect of the present invention, in the method for manufacturing a metal cylinder described in the first or second aspect, a rod-shaped cored bar having an outer diameter corresponding to an intended inner diameter of the belt-shaped body. By extrapolating the band-like body to a tool, the band-like body is held in a state of a desired diameter.

  According to the third aspect, the diameter of the band can be easily set to the target diameter by extrapolating the band to the metal core jig. In particular, even when a strip obtained by bending a metal base plate is not easily held to the desired diameter by a spring back, the strip is held along the outer peripheral surface of the metal core jig. Can be easily held at the desired diameter.

  According to a fourth aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to third aspects, the metal core in the composite electrode is made of a stainless steel metal, and the composite electrode The periphery of the metal core is a copper-based metal.

  According to the fourth aspect, since the metal core of the composite electrode is made of a stainless steel metal, sufficient durability (abrasion resistance) of the metal core is obtained by a relatively inexpensive and easily available material. Thus, even if the metal core is repeatedly pressed against the convex portion of the belt-like body that is the material to be welded, the wear of the welding electrode can be suppressed. On the other hand, since the periphery of the metal core in the composite electrode is made of copper-based metal having excellent conductivity, current can be efficiently passed between a pair of welding electrodes, and welding by resistance heating is effective. Realized.

  According to a fifth aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to fourth aspects, the overlapping portions at both ends of the belt-like body are overlapped on the inner peripheral side. The convex portion is formed on the inner peripheral surface of the overlapping portion, and the concave portion is formed on the outer peripheral surface of the overlapping portion overlapped on the outer peripheral side.

  According to the fifth aspect, it is easy to avoid the formation of the protruding portion due to the convex portion on the outer peripheral surface of the manufactured metal cylinder, and in particular, when other members are extrapolated to the metal cylinder. As described above, even when the roundness or the like is required with high accuracy on the outer peripheral surface, it becomes easy to cope with it.

  According to a sixth aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to fifth aspects, welding is performed on the welded portions at the overlapping portions at both ends of the strip-shaped body. Later, cutting or polishing is performed.

  According to the sixth aspect, by reducing the unevenness remaining in the overlapped portion after welding by cutting or polishing, the inner and outer diameter accuracy of the metal cylinder can be further improved, and the inner peripheral surface of the metal cylinder In addition, the outer peripheral surface can be made smoother. In addition, by adjusting the surface shape of the welded part by cutting or polishing after welding, it is possible to repeatedly achieve the desired dimensional accuracy of the inner and outer diameters and smoothness of the inner and outer peripheral surfaces of the metal cylinder, making it more stable. It is also possible to provide a metal cylinder of the quality.

  According to a seventh aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to sixth aspects, an inner peripheral side and an outer periphery of at least one end edge in the width direction of the belt-shaped body. A tapered surface is formed by pressing at least one corner on the side.

  According to the seventh aspect, it is possible to easily attach a tapered surface such as a C surface or an R surface to the corner portion (edge portion) by pressing before forming the metal base plate into a cylindrical body. Chamfering of corners of products (metal cylinders) can be easily and highly accurately performed compared to the case of manufacturing a cylinder by cutting the tube obtained by thinning out with an appropriate length. it can.

  According to an eighth aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to seventh aspects, the overlapping portions at both ends of the belt-shaped body are arranged in the width direction of the belt-shaped body. It is formed continuously over the entire length.

  According to the eighth aspect, the overlapping portion can be provided in a wide range in the width direction of the belt-shaped body, and the overlapping portions can be held more stably in a state of overlapping each other. It becomes easy to prevent twisting and displacement of the body. In addition, processing for forming the overlapping portion on the flat metal base plate is facilitated, and more accurate inner and outer diameter dimensions of the metal cylinder can be realized.

  According to a ninth aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to eighth aspects, the welding of the pair of welds is performed at the overlapping portion at both ends of the strip-shaped body. The electrode is pressed against one of the concave portion and the convex portion to make the depth dimension of the concave portion and the height dimension of the convex portion smaller than before welding.

  According to the ninth aspect, after welding, the concave and convex portions are compressed between a pair of welding electrodes during welding, so that the depth dimension of the concave portion and the height dimension of the convex portion are made smaller than before welding. In the obtained metal cylinder, the inner peripheral surface and the outer peripheral surface are smooth surfaces with less irregularities, and the accuracy of the inner diameter dimension and the outer diameter dimension is improved.

  According to a tenth aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to ninth aspects, the thickness of the strip is set to 0.5 mm to 4.0 mm. It is.

  By setting the thickness dimension of the belt-like body to be equal to or greater than the lower limit (0.5 mm) of the thickness dimension shown in the tenth aspect, the overlapping portion, the concave portion and the convex portion can be stably formed on the belt-like body. It becomes easy. On the other hand, when the thickness dimension of the belt-like body is not more than the upper limit (4.0 mm) of the thickness dimension shown in the tenth aspect, the desired shape of the metal cylinder can be easily realized by bending or welding. At the same time, it is easy to join the overlapping portions by spot welding or the like.

  According to an eleventh aspect of the present invention, in the method for manufacturing a metal cylinder described in any one of the first to tenth aspects, the depth dimension of the recess is defined as one of the strips including the recess. The height of the projection is set to be equal to or less than the plate thickness of the overlapping portion, and the height of the convex is set to be equal to or less than the thickness of the other overlapping portion of the belt-like body including the projection.

  According to the eleventh aspect, the mechanical strength can be sufficiently easily obtained at the formation site of the concave portion and the convex portion, and stable workability can be ensured. Furthermore, it becomes easy to make the unevenness | corrugation of a welding part small in the metal cylinder after welding.

  According to the present invention, when a flat metal base plate is bent and both end portions are welded and connected to each other, for example, chamfering or the like is required at the corners at both ends in the axial direction of the metal cylinder. In addition, the metal cylinder can be manufactured at low cost. Furthermore, the belt-like body can be held at the target diameter by engagement of the concave and convex portions formed in the overlapping portion, and the metal cylinder can be easily and stably formed with the target diameter. Can do. In particular, by forming each of the concave and convex portions at the same time in a state where the belt-like body is held at a desired diameter, the concave and convex portions can be easily engaged with each other at appropriate positions. Can be formed. In addition, since at least one of the pair of welding electrodes pressed against the convex portion is a composite electrode having a metal core harder than the periphery with respect to the center of the tip, the pressing to the convex portion The wear at the center of the tip of the welding electrode is reduced, and the durability of the welding electrode is improved.

The perspective view which shows the metal cylinder as 1st embodiment of this invention. The front view of the metal cylinder shown in FIG. III-III sectional drawing of FIG. The front view which shows the state which formed the overlap part and the taper surface in the metal base plate which is a formation part of the metal cylinder of FIG. FIG. 5 is a bottom view of the metal base plate after forming the overlapping portion and the tapered surface shown in FIG. 4. VI-VI sectional drawing of FIG. The figure which shows the process of giving a bending process to the metal base plate after superposition part and taper surface formation shown in FIG. The figure which expands and shows the principal part of the strip | belt-shaped body formed by the process of FIG. IX-IX sectional drawing of FIG. The figure which shows the process of welding the both ends of the strip | belt-shaped body of FIG. The perspective view of the electrode for welding shown in FIG. The perspective view which shows the metal cylinder as 2nd embodiment of this invention. The figure which expands and shows the principal part of the strip | belt-shaped body which comprises the metal cylinder shown in FIG. XIV-XIV sectional drawing of FIG. The top view of the 1st electrode for welding used for welding of the both ends of the strip | belt-shaped body shown in FIG. XVI-XVI sectional drawing of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  1-3, the metal cylinder 10 manufactured by the manufacturing method of the metal cylinder as 1st embodiment of this invention is shown. The metal cylinder 10 is formed of a metal material such as iron or stainless steel, and has a substantially cylindrical shape extending linearly. Furthermore, the metal cylinder 10 is formed into a substantially cylindrical shape by bending a flat metal base plate 12 (see FIGS. 4 to 6) with a press and joining both ends by welding.

  More specifically, the metal cylinder 10 is manufactured by, for example, the following method for manufacturing a metal cylinder.

  First, the length direction (left-right direction in FIG. 4) both ends of the rectangular flat plate-shaped metal base plate 12 prepared in advance by press working such as shearing are thinned by crushing in the thickness direction by press working, Overlapping portions 14a and 14b for connection are formed on both ends of the metal base plate 12 (see FIGS. 4 and 5).

  The length dimension and width dimension of the metal base plate 12 are not particularly limited, and are appropriately set according to the diameter and axial length of the target metal cylinder 10. Moreover, although the thickness dimension of the metal base plate 12 can also be set suitably, the thickness dimension is suitably set to the range of 0.5 mm-4.0 mm. By setting the thickness dimension of the metal base plate 12 in such a range, the overlapping portions 14a and 14b, the concave portions 24 and the convex portions described later are formed on the band-shaped body 20 described later formed from the metal base plate 12. 26 can be stably formed, and the metal cylinder 10 having a desired shape can be easily and highly accurately formed from the metal base plate 12 by bending or welding, and the overlapping portion by welding can be formed. The bonding strength of 14a and 14b can be effectively obtained.

  The overlapping portions 14a and 14b formed at both end portions of the metal base plate 12 are formed by crushing both end portions of the metal base plate 12 in the thickness direction by press working, and the width direction of the metal base plate 12 Are provided continuously over the entire length. Further, as shown in FIG. 4, the one overlapping portion 14 a has a thin shape that is thin from the one side in the thickness direction (the upper side in FIG. 4) that is the inner peripheral side of the metal cylinder 10, The other overlapping portion 14b has a thin shape that is thin from the other side (the lower side in FIG. 4) in the thickness direction, which is the outer peripheral side of the metal cylinder 10. Thereby, the steps 16 and 16 are formed on the opposite surfaces, and the overlapping portions 14a and 14b are biased to one side in the thickness direction with respect to the center in the thickness direction of the metal base plate 12. ing. The thickness dimension of the overlapping portions 14a and 14b is half of the thickness dimension of the metal base plate 12, in other words, the thickness dimension of the intermediate portion of the strip-shaped body 20 which will be described later, excluding the overlapping portions 14a and 14b. The following is desirable, and the thickness is more preferably about half.

  In addition, when the metal base plate 12 is crushed in the thickness direction to form the overlapping portions 14a and 14b, the metal base plate 12 has a surface direction such as a width direction (vertical direction in FIG. 5) in the overlapping portions 14a and 14b. Therefore, if necessary, after the formation of the overlapping portions 14a and 14b, portions extending outward in the width direction and the length direction are removed by shear pressing. Further, for example, at the time of such shear pressing, a taper surface 18 by pressing may be attached to a corner of at least one end edge in the width direction of the metal base plate 12. The tapered surface 18 only needs to be attached to at least one corner of the inner peripheral side and the outer peripheral side of the metal cylinder 10, and in this embodiment, as shown in FIG. 10 is attached to a corner portion on the inner peripheral side, and is inclined to the outer side in the thickness direction (the left side in FIG. 6, which is the outer peripheral side of the metal cylinder 10) as it goes inward in the width direction of the metal base plate 12.

  Next, the metal base plate 12 is curved in the thickness direction by press working, and the overlapping portions 14a and 14b which are both end portions are overlapped with each other to obtain the cylindrical belt-like body 20. In the step of forming the band-like body 20 by such bending, for example, after the metal base plate 12 is bent to some extent by progressive press processing, the metal base plate 12 is formed into a substantially cylindrical outer periphery as shown in FIG. A strip-shaped body 20 having a desired shape is obtained by extrapolating the rod-shaped cored bar jig 22 having a surface and performing further bending so as to have a shape along the outer peripheral surface of the cored bar jig 22. Can do. The metal core jig 22 is formed with an outer diameter corresponding to the inner diameter of the target metal cylinder 10 and a radius of curvature corresponding to the inner peripheral surface of the metal cylinder 10.

  Next, in the belt-like body 20, the concave portion 24 and the convex portion 26 are simultaneously formed in the overlapping portions 14a and 14b overlapped with each other, thereby completing the concave-convex forming step. That is, as shown in FIG. 7, the overlapping portions 14 a and 14 b are arranged on the outer periphery while holding the belt-like body 20 in a state in which the belt-like body 20 has a target diameter dimension by superposing the belt-like body 20 on the outer peripheral surface of the cored bar jig 22. It is pushed from the side with a pressing jig 28 such as a punch to the inner peripheral side and deformed so as to protrude toward the inner peripheral side. The cored bar jig 22 of the present embodiment opens to the outer peripheral surface with respect to the portion supporting the inner peripheral side of the overlapping portions 14a and 14b and linearly extends in the axial direction (the direction orthogonal to the paper surface in FIG. 7). The extending cutout 30 is provided, and the belt-like body 20 pushed to the inner peripheral side by the pressing jig 28 is allowed to project into the inner peripheral side by entering the cutout 30. . As described above, when the overlapping portions 14a and 14b in a state of being overlapped with each other are simultaneously and integrally deformed, the concave portion 24 is formed in one overlapping portion 14a disposed on the outer peripheral side of the belt-like body 20. At the same time, the convex portion 26 is formed on the other overlapping portion 14 b disposed on the inner peripheral side of the belt-like body 20.

  As shown in FIGS. 8 and 9 in an enlarged manner, the recess 24 opens toward the radially outer side (the upper side in FIG. 8) of the band-like body 20 in one overlapping portion 14a. The body 20 has a groove shape extending continuously in a substantially constant cross-sectional shape over the entire length in the width direction (left-right direction in FIG. 9). On the other hand, the convex portion 26 protrudes toward the radially inner side (the lower side in FIG. 8) of the band-like body 20 in the other overlapping portion 14b. It has a ridge shape extending continuously with a substantially constant cross-sectional shape.

  Furthermore, since the concave portion 24 and the convex portion 26 are formed by bending the flat plate-like overlapping portions 14a and 14b so as to be partially convex inward in the thickness direction, The radially inner side of the portion where the concave portion 24 is formed has a convex shape protruding toward the inner side in the radial direction of the belt-like body 20 and the radially outer side of the portion where the convex portion 26 is formed in the other overlapping portion 14b. The groove 20 has a groove shape that opens outward in the radial direction of the belt-like body 20.

  Furthermore, as shown in FIG. 8, the concave portion 24 is gradually widened toward the opening side, and the inner surface of the concave portion 24 has a tapered shape that gradually tilts downward from the left and right ends toward the middle in the left and right directions. Yes. Similarly, the convex portion 26 is gradually narrower as it goes to the protruding tip side, and the outer surface of the convex portion 26 has a tapered shape that gradually inclines from both ends in the left-right direction toward the middle in the left-right direction. As described above, since both surfaces of the formation portions of the concave portions 24 or the convex portions 26 in the overlapping portions 14a and 14b have substantially corresponding shapes, the concave portions 24 or the convex portions in the overlapping portions 14a and 14b. 26 is formed in a tapered shape that is inclined with a substantially constant thickness.

  The depth dimension d of the recess 24 is preferably set to be equal to or less than the thickness dimension t1 of the one overlapping portion 14a where the recess 24 is formed (d ≦ t1), and the height dimension of the protrusion 26 h is preferably equal to or less than the thickness dimension t2 of the other overlapping portion 14b on which the convex portion 26 is formed (h ≦ t2). According to this, in the formation site | part of the recessed part 24 and the convex part 26 in the overlapping parts 14a and 14b, it becomes easy to fully obtain mechanical strength, and can ensure the stable workability.

  Here, since the concave portion 24 and the convex portion 26 are simultaneously formed in a state where the overlapping portions 14a and 14b are overlapped with each other as described above, the formation portion of the concave portion 24 in the overlapping portions 14a and 14b is convex. The concave portion 24 and the convex portion 26 can be engaged with each other in the circumferential direction of the belt-like body 20 by being inserted into the formation portion of the portion 26. Then, by engaging the concave portion 24 and the convex portion 26, the overlapping portions 14a and 14b can be positioned at appropriate circumferential positions, and the belt-like body 20 can be held at a target radial dimension.

  The overlapping portions 14a and 14b are formed by spot welding or the like in the portions where the concave portions 24 and the convex portions 26 are formed, while the concave portions 24 and the convex portions 26 are engaged to hold the belt-shaped body 20 in a state of a desired diameter. By joining by lap resistance welding, the both ends of the strip | belt-shaped body 20 are connected, and the metal cylinder 10 is formed.

  That is, as shown in FIG. 10, the first welding electrode 32 is placed on the belt-like body 20 with respect to the overlapping portions 14 a and 14 b of the belt-like body 20 held in a cylindrical shape by the engagement of the concave portion 24 and the convex portion 26. The second welding electrode 34 is pressed against the concave portion 24 or the periphery of the concave portion 24 from the outer peripheral side of the band-shaped body 20 to press against the first welding electrode 32 and the first welding electrode 32. The second welding electrode 34 is abutted through the concave portion 24 and the convex portion 26 of the overlapped portions 14a and 14b, which are materials to be welded. And between the first welding electrode 32 and the second welding electrode 34, the overlapping portions 14 a and 14 b are pressed between the first welding electrode 32 and the second welding electrode 34. By passing an electric current, the overlapping portions 14 a and 14 b are fixedly joined at the engaging portion of the concave portion 24 and the convex portion 26 by heat generation and pressure contact due to electric resistance.

  The first welding electrode 32 is a composite electrode formed of a composite material in which a metal core 38 is incorporated at the tip of the electrode body 36. The electrode main body 36 is formed of a copper-based metal having excellent conductivity, and as shown in FIGS. 10 and 11, a tapered shape in which the tip portion gradually becomes narrower toward the tip side (upper side in FIG. 10). have. The metal core 38 is formed of a metal material such as a stainless steel metal that is harder than the electrode main body 36, and press-fitting or brazing into a hole opened at the tip of the electrode main body 36, and after being inserted into the hole, squeezing, swaging, etc. The electrode body 36 is fixed to the distal end portion of the electrode body 36 by various methods such as applying the process to the electrode body 36 and fitting it. In other words, the first welding electrode 32 has a structure in which an electrode body 36 having excellent conductivity is disposed around a hard metal core 38 having excellent wear resistance disposed at the center of the tip. . On the other hand, the second welding electrode 34 is formed entirely of a copper-based metal having high conductivity.

  The first welding electrode 32 and the second welding electrode 34 are connected to separate actuators (not shown), and can be moved relative to each other in directions approaching or separating from each other. In particular, the actuator is capable of pressing the first and second welding electrodes 32 and 34 against the overlapping portions 14a and 14b with a force having a magnitude necessary for welding. The engaging portion of the concave portion 24 and the convex portion 26 in the overlapping portions 14a and 14b is pressurized in the approaching direction.

  The first welding electrode 32 and the second welding electrode 34 are connected to a power supply device 44 via a transformer 40 and a control device 42, and the first welding electrode 32 and the second welding electrode 34 are controlled by the power supply device 44 controlled by the control device 42. A predetermined current can be passed through the welding electrode 32 and the second welding electrode 34. Then, by passing a current through the first welding electrode 32 and the second welding electrode 34, the convex portion 26 superimposed on the first welding electrode 32 and the second welding electrode 34 are superimposed. Spot welding is performed on the engaging portion of the recess 24 to join the overlapping portions 14a and 14b to each other.

  Furthermore, by welding the concave portion 24 and the convex portion 26 and crushing the concave portion 24 and the convex portion 26 in the radial direction of the belt-like body 20 while heating, the depth dimension of the concave portion 24 and the convex portion 26 after the welding is completed. The height dimension of each is smaller than before welding. Thereby, it is possible to set the target inner diameter and outer diameter in the overlapping portions 14a and 14b with high accuracy, and the amount of protrusion of the concave portion 24 and the convex portion 26 to the inner and outer peripheral surfaces is reduced. In particular, in the present embodiment, the depth dimension d of the recess 24 is equal to or less than the thickness dimension t1 of the one overlapping portion 14a, and the height dimension h of the recess 24 is the thickness dimension of the other overlapping portion 14b. Since it is set to t2 or less, the unevenness | corrugation of a welding site | part can be made smaller in the metal cylinder 10 after welding.

  In addition, you may perform a cutting process and grinding | polishing process after the completion of welding with respect to the formation part of the recessed part 24 and the convex part 26 which are the welding parts of the overlapping parts 14a and 14b. By performing such post-processing, unevenness remaining in the overlapped portions 14a and 14b after welding can be reduced by cutting or polishing, and the dimensional accuracy of the inner and outer diameters of the metal cylinder 10 can be further improved. The inner peripheral surface and outer peripheral surface of the cylindrical body 10 can be made smoother. However, the unevenness of the portions where the concave portions 24 and the convex portions 26 are formed on the inner and outer peripheral surfaces of the belt-like body 20 may be sufficiently reduced by pressure welding at the time of welding, in which case post-processing such as cutting and polishing is performed. Without this, the accuracy of the inner and outer diameters of the metal cylinder 10 and a smooth inner and outer peripheral surface can be obtained.

  After completing the welding process of connecting the both ends of the belt-like body 20 as described above by welding, by removing the belt-like body 20 welded at both ends from the core metal jig 22, the target metal cylinder 10 is obtained. Can be obtained.

  According to the manufacturing method of the metal cylinder 10 according to the present embodiment, the metal cylinder 10 can be manufactured at low cost by performing press working and welding on the flat metal base plate 12. In addition, the tapered surfaces 18 are formed by pressing or the like on the corners at both ends in the width direction of the metal base plate 12 before being bent by pressing, so that the corners at both ends in the axial direction of the metal cylinder 10 are formed. A process such as chamfering can be easily and highly accurately performed as compared with the case of manufacturing a metal cylinder by cutting a tube formed by cold drawing.

  In addition, in the state where the overlapping portions 14a and 14b for connection are provided at both ends of the band-shaped body 20 formed by bending the flat metal base plate 12, the band-shaped body 20 is held at a target diameter. By forming each of the concave portion 24 and the convex portion 26 at the same time with respect to the overlapping portions 14a and 14b at both ends, the belt-like body 20 can be accurately adjusted to the target diameter by the engagement of the concave portion 24 and the convex portion 26. Can hold well. As a result, when the overlapping portions 14a and 14b at both ends of the belt-like body 20 are joined by welding, the overlapping portions 14a and 14b can be relatively positioned by the engagement of the concave portion 24 and the convex portion 26. The metal cylinder 10 having a desired diameter can be easily manufactured with good dimensional accuracy.

  In addition, since the concave portion 24 and the convex portion 26 are formed at the same time in the state where the belt-like body 20 is held at a desired diameter and the overlapping portions 14a and 14b are overlapped, the concave portion 24 and the convex portion 26 are engaged in advance. Formed in the state. Therefore, compared with the case where each of the concave portion 24 and the convex portion 26 is separately formed in the overlapping portions 14a and 14b, the concave portion 24 and the convex portion 26 are not made incapable of being engaged due to a dimensional error or the like. In addition, there is no gap formed between the concave portion 24 and the convex portion 26 so as to cause a problem in dimensional accuracy. Therefore, the overlapping portions 14a and 14b can be stably positioned with high accuracy by the engagement of the concave portion 24 and the convex portion 26, and the high-quality metal cylinder 10 having excellent dimensional accuracy and surface shape can be stabilized. Can be manufactured.

  Furthermore, the formation part of the recessed part 24 in one superimposition part 14a has the taper shape which becomes narrow toward the superimposition surface of the other superposition part 14b, and the convex in the other superimposition part 14b. The formation part of the part 26 has a taper shape which becomes wide toward the overlapping surface of the one overlapping part 14a. Accordingly, the engagement and the release of the concave portion 24 and the convex portion 26 can be easily realized arbitrarily without being caught by the guiding action exhibited between the overlapping surfaces of the concave portion 24 forming portion and the convex portion 26 forming portion. It has become. In addition, the taper shape of the formation part of the concave part 24 and the formation part of the convex part 26 can be easily obtained by pressing the overlapping parts 14a and 14b from the outer peripheral side with the pressing jig 28 to be deformed. it can.

  Further, the overlapping portions 14a and 14b are continuously formed over the entire length in the width direction of the band-shaped body 20, so that the overlapping portions 14a and 14b are provided in a wide range in the width direction of the band-shaped body 20, Since the mating portions 14a and 14b can be held more stably in a state where they overlap each other, it becomes easy to prevent the belt-like body 20 from being twisted or displaced. Moreover, formation of the overlapping portions 14a and 14b on the metal base plate 12 is facilitated, and more accurate inner and outer diameter dimensions of the metal cylinder 10 can be realized.

  Further, the one overlapping portion 14a is thinned from the inner peripheral side of the strip-shaped body 20, and the other overlapping portion 14b is thinned from the outer peripheral side of the strip-shaped body 20, so that the inner peripheral surface of the one overlapping portion 14a The outer peripheral surfaces of the other overlapping portion 14b are overlapped with each other. Therefore, in the portion where the overlapping portions 14a and 14b are overlapped with each other, the thickness dimension of the metal cylinder 10 is prevented from partially increasing, and the accuracy of the inner diameter dimension and the outer diameter dimension of the metal cylinder body 10 is prevented. Can be obtained at high altitude over the entire circumference. In particular, in the present embodiment, the thickness dimension of the overlapping portions 14a and 14b in the belt-like body 20 is approximately ½ of the thickness dimension of the intermediate portion outside the overlapping portions 14a and 14b. The change of the thickness dimension can be suppressed over the entire circumference of the ten, and the highly accurate setting of the inner and outer diameter dimensions and the reduction of the irregularities on the inner and outer peripheral surfaces can be realized.

  In the present embodiment, the concave portion 24 and the convex portion 26 are simultaneously formed by pressing the pressing jig 28 from the outer peripheral side against the overlapping portions 14a and 14b overlapped with each other. A convex portion 26 is formed on the inner peripheral surface of one overlapping portion 14a that is overlapped on the side, and a concave portion 24 is formed on the outer peripheral surface of the other overlapping portion 14b that is overlapped on the outer peripheral side. Therefore, it is difficult to form a protruding portion after welding on the outer peripheral surface of the metal cylinder 10. For example, even when another member is extrapolated to the metal cylinder 10, a partial portion of the outer peripheral surface of the metal cylinder 10 is used. It becomes easy to cope by preventing protrusion.

  In addition, in the overlapping portions 14a and 14b, the first welding electrode 32 and the second welding electrode 34 are abutted in the radial direction of the band-shaped body 20 at the engagement portion between the concave portion 24 and the convex portion 26, so that the overlapping portion By joining 14a and 14b in the thickness direction by welding, the unevenness of the inner and outer peripheral surfaces of the metal cylinder 10 due to the weld bead is reduced, and the metal cylinder 10 having the desired inner and outer diameter dimensions can be obtained with high accuracy. Can do. In the present embodiment, the concave portion 24 and the convex portion 26 are provided in a shape that is continuous over the entire length in the width direction of the overlapping portions 14a and 14b, and the overlapping portion is formed in the welded portion in which the concave portion 24 and the convex portion 26 are formed. Since 14a and 14b are continuously joined over the entire length in the width direction, it is possible to fluid-tightly seal the overlapping surfaces of the overlapping portions 14a and 14b in the welded portion.

  Further, the first welding electrode 32 that is easily worn by being pressed against the convex portion 26 is a composite electrode including a metal core 38 that is harder than the electrode body 36 at the center of the tip end of the electrode body 36. . As a result, the wear at the center of the tip of the first welding electrode 32 due to pressing against the convex portion 26 is reduced, and the durability of the first welding electrode 32 is improved.

  In addition, by making the metal core 38 of the first welding electrode 32 a stainless steel metal, sufficient durability (wear resistance) can be obtained with an easily available and relatively inexpensive material, and a belt-like shape. Even if repeatedly pressed against the convex portion 26 of the body 20, the wear of the first welding electrode 32 can be suppressed. Moreover, the electrode main body 36 of the first welding electrode 32 that is not directly pressed against the convex portion 26 is made of a copper-based metal having excellent conductivity, whereby the first welding electrode 32 and the second welding electrode 32 are made. It is possible to effectively realize welding by resistance heat generation by efficiently passing a current between the welding electrodes 34.

  Further, the concave portion 24 and the convex portion 26 are compressed between the first welding electrode 32 and the second welding electrode 34 at the time of welding, so that the depth dimension of the concave portion 24 and the height dimension of the convex portion 26 are set before welding. By making it smaller, the inner peripheral surface and the outer peripheral surface of the metal cylinder 10 obtained after welding become smooth surfaces with less irregularities, and the accuracy of the inner diameter dimension and the outer diameter dimension of the metal cylinder body 10 is also improved. Figured.

  Further, by extrapolating the band-like body 20 to the metal core jig 22 during the processing of the band-like body 20, the diameter dimension of the band-like body 20 can be easily set to a target diameter dimension. In particular, even when the belt-like body 20 obtained by bending the metal base plate 12 is not easily held to a desired diameter by a spring back alone, the belt-like body 20 extends along the outer peripheral surface of the cored bar jig 22. By holding, the belt-like body 20 can be easily held at a target diameter.

  FIG. 12 shows a metal cylinder 50 manufactured by the method for manufacturing a metal cylinder as the second embodiment of the present invention. As shown in FIGS. 13 and 14, the metal cylinder 50 according to the present embodiment includes overlapping portions 54 a and 54 b provided at both ends of the belt-like body 52, and concave portions 56 and 54 provided at two places in the width direction. Formed by welding the engaging portions of the concave portions 56, 56 and the convex portions 58, 58 in a state of being positioned at an appropriate relative position in the circumferential direction by the engagement of the convex portions 58, 58 with the 56. Is done. As can be seen from the above description, the manufacturing process of the metal cylinder 50 is substantially the same as that of the first embodiment, but in this embodiment, the concave portion 24 and the convex portion of the first embodiment are used. Concave portions 56, 56 and convex portions 58, 58 having a structure different from that of 26 are formed.

  That is, the concave portion 56 is formed in a substantially circular concave shape that opens toward the outer peripheral side with respect to the one overlapping portion 54a located on the outer peripheral side of the belt-like body 52, and the two concave portions 56 and 56 are formed in the width direction. Are placed apart from each other. On the other hand, the convex portion 58 is formed in a substantially conical convex shape that protrudes toward the inner peripheral side with respect to the other overlapping portion 54 b located on the inner peripheral side of the belt-like body 52, and the two convex portions 58 are formed. , 58 are spaced apart from each other in the width direction.

  Further, the pressing jig 28 is pressed against the overlapping portions 54a and 54b from the outer peripheral side of the belt-like body 52 in a state where the overlapping portions 54a and 54b of the belt-like body 52 are overlapped with each other at an appropriate position. By partially deforming the portions 54a and 54b to the inner peripheral side, the concave portion 56 and the convex portion 58 are formed simultaneously. In addition, if the recessed part 56 and the convex part 58 which are mutually engaged are formed simultaneously, the two recessed parts 56 and 56 or the two convex parts 58 and 58 may not necessarily be formed simultaneously, but all the recessed parts If 56 and 56 and convex parts 58 and 58 are formed simultaneously, the number of manufacturing steps can be reduced.

  And the formation part of the recessed part 56 in one overlap part 54a is inserted in the formation part of the convex part 58 in the other overlap part 54b, and the formation part of these recessed part 56 and the formation part of the convex part 58 are strip | belt-shaped bodies. By being engaged with each other in the circumferential direction and the width direction of 52, the belt-like body 52 is held at a predetermined diameter.

  In this state, the end portions of the band-like body 52 are welded by welding the engaging portions of the concave portions 56, 56 and the convex portions 58, 58 in the overlapping portions 54a, 54b with the belt-like body 52 held at a predetermined diameter. Can be fixedly joined to each other to obtain the metal cylinder 50.

  In the present embodiment, since the concave portions 56 and 56 and the convex portions 58 and 58 are circular in the radial direction of the band-shaped body 52, respectively, instead of the first welding electrode 32 of the first embodiment. A first welding electrode 60 as shown in FIGS. 15 and 16 is employed. That is, the first welding electrode 60 includes an electrode body 62 that is formed of a metal material having excellent conductivity, such as a copper-based metal, and has a circular block shape that extends vertically in a substantially circular cross section. Further, the tip (upper end in FIG. 16) surface of the electrode body 62 is an arcuate curved surface that curves substantially along the inner peripheral surface of the strip 52, and the electrode body 62 has an electrode at the center of the tip. A substantially cylindrical metal core 64 made of stainless steel or the like having higher hardness than the main body 62 is embedded and arranged.

  The first welding electrode 60 is pressed against the convex portion 58 of the strip 52 from the inner peripheral side, and the second welding electrode (not shown) is pressed against the concave portion 56 of the strip 52 from the outer peripheral side. The current is applied while compressing the engaging portions of the concave portions 56 and the convex portions 58 in the overlapping portions 54a and 54b. As a result, resistance welding such as spot welding is applied to the engaging portion between the concave portion 56 and the convex portion 58, and the overlapping portions 54a and 54b are joined to each other at the engaging portion between the concave portion 56 and the convex portion 58.

  The concave portions 56 and 56 and the convex portions 58 and 58 that are partially formed in the width direction of the belt-like body 52 shown in the present embodiment are also continuous concave portions over the entire length in the width direction shown in the first embodiment. 24 and the convex part 26 can be obtained, and the metal cylinder 50 having a desired inner / outer diameter can be easily manufactured by a press fitting. In short, the concave portion and the convex portion formed in the overlapping portion of the belt-like body are limited in shape, number of formations, arrangement, and the like as long as the overlapping portion can be relatively positioned by engagement. It is not a thing.

  In the present embodiment, the overlapping portions 54a and 54b provided with the spot-like welded portions by the concave portions 56 and 56 and the convex portions 58 and 58 are exemplified, but, for example, a line extending in a width direction that does not reach the full length It is also possible to employ a superposed portion having a structure including a welded portion having a shape or a structure including a meandering welded portion extending in the width direction while being bent or bent.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, the metal cylinder is not limited to a cylindrical shape. For example, a metal cylinder having a polygonal cylinder shape such as a rectangular cylinder or a metal cylinder having an irregular cylinder shape such as a star cylinder The present invention can also be applied to the above. In addition, for example, by processing a metal base plate having a width corresponding to an approximately integral multiple of the axial dimension of the target metal cylinder 10 into a cylindrical shape by pressing and welding, and then cutting into a plurality of pieces A plurality of metal cylinders 10 can be obtained from one metal base plate.

  Moreover, in the said embodiment, while forming the recessed part 24 in the one overlapping part 14a located in the outer peripheral side of the strip | belt shaped object 20, it is the convex part 26 in the other overlapping part 14b located in the inner peripheral side of the strip | belt shaped object 20. However, it is difficult to form a protruding portion on the outer peripheral surface of the metal cylinder 10, but the convex portion 26 is formed on the one overlapping portion 14 a located on the outer peripheral side of the belt-like body 20, and the belt-like shape is formed. By forming the recess 24 in the other overlapping portion 14 b located on the inner peripheral side of the body 20, it is possible to make it difficult for the protruding portion to be formed on the inner peripheral surface of the metal cylinder 10. According to this, a smooth inner peripheral surface can be set on the metal cylinder 10 and the dimensional accuracy of the inner diameter can be improved. It becomes easy to do.

  Further, the material for forming the hard metal core 38 of the first welding electrode 32 is preferably a stainless steel metal that is easily available and relatively inexpensive, but is harder than the electrode body 36 and has a certain degree. Any metal material having electrical conductivity may be used. For example, a molybdenum-based metal or a tungsten-based metal may be employed. Further, the material for forming the electrode main body 36 and the second welding electrode 34 of the first welding electrode 32 is not necessarily limited to the copper-based metal, and an aluminum-based metal or the like may be adopted. Note that the belt-like body 20 that is the material to be welded, the first welding electrode 32 and the second welding electrode 34 are preferably made of different materials, and in particular, the metal core of the first welding electrode 32. 38 is preferably made of a material different from that of the belt-like body 20.

  Furthermore, in the said embodiment, since the recessed part 24 and the convex part 26 become convex shape toward the inner peripheral side of the strip | belt-shaped body 20, the 1st electrode 32 for welding which is a composite electrode provided with the metal core 38 is provided. For example, when the concave portion 24 and the convex portion 26 are convex toward the outer peripheral side of the band-shaped body 20, the first welding that is a composite electrode is arranged on the inner peripheral side of the band-shaped body 20. The working electrode 32 is disposed on the outer peripheral side of the belt-like body 20. In short, the durability of the welding electrode can be improved by forming the electrode on the concave portion 24 side where wear due to contact with the member to be welded becomes a problem as a composite electrode including the metal core 38.

10, 50: Metal cylinder, 12: Metal base plate, 14, 54: Overlapping part, 18: Taper, 20, 52: Strip body, 22: Core metal jig, 24, 56: Recess, 26, 58: Projection, 32, 60: first welding electrode (composite electrode), 34: second welding electrode, 36, 62: electrode body, 38, 64: metal core

Claims (11)

A method of manufacturing a metal cylinder,
A step of bending a flat plate-shaped metal base plate to obtain a band-shaped body provided with overlapping portions for connection at both ends in the bending direction;
Simultaneously forming a concave portion and a convex portion that are engaged with each other between the overlapping surfaces at both ends, while holding the overlapping portions at both ends of the belt-like body in a state of having a desired diameter.
At least one of the pair of welding electrodes that are abutted across the material to be welded is a composite electrode having a metal core that is harder than the periphery relative to the center of the tip, and the concave portion and the convex portion In a state where the belt-like body is held at a desired diameter by being engaged with each other, the pair of welding electrodes are abutted against the engaging portion of the concave portion and the convex portion, and one of the composite electrodes is formed. A step of fixedly joining the overlapping portions at both ends of the belt-like body by pressing the metal core of the welding electrode against the convex portion to perform welding. Manufacturing method.   2. The metal cylinder according to claim 1, wherein one of the overlapping portions of the belt-like body has a thin shape that is thin from an inner peripheral side, and the other overlapping portion is a thin shape that is thin from an outer peripheral side. Manufacturing method.   The rod-shaped body is held in a state of a desired diameter size by extrapolating the band-shaped body to a rod-shaped cored bar jig having an outer diameter corresponding to a desired inner diameter of the band-shaped body. The manufacturing method of the metal cylinder of 1 or 2.   The method for producing a metal cylinder according to any one of claims 1 to 3, wherein the metal core in the composite electrode is made of a stainless steel metal and the periphery of the metal core in the composite electrode is made of a copper metal.   In the overlapping portion at both ends of the belt-like body, the convex portion is formed on the inner peripheral surface of the overlapping portion that is overlapped on the inner peripheral side, while on the outer peripheral surface of the overlapping portion that is overlapped on the outer peripheral side. The manufacturing method of the metal cylinder as described in any one of Claims 1-4 which forms the said recessed part.   The manufacturing method of the metal cylinder as described in any one of Claims 1-5 which performs a cutting process or grinding | polishing process after welding with respect to the welding part in the said overlap part of the both ends of the said strip | belt-shaped body.   The metal cylinder as described in any one of Claims 1-6 which forms the taper surface by press work in at least one corner | angular part of the inner peripheral side and outer peripheral side in the at least one edge part of the width direction of the said strip | belt-shaped body. Manufacturing method.   The manufacturing method of the metal cylinder as described in any one of Claims 1-7 which forms the said overlapping part of the both ends of the said strip | belt shaped object continuously over the full length of the width direction of this strip | belt shaped object.   During welding at the overlapping portions at both ends of the belt-like body, the pair of welding electrodes are pressed against one of the concave portion and the convex portion so that the depth dimension of the concave portion and the height dimension of the convex portion are before welding. The manufacturing method of the metal cylinder as described in any one of Claims 1-8 made smaller.   The manufacturing method of the metal cylinder as described in any one of Claims 1-9 which sets the thickness dimension of the said strip | belt shaped object to 0.5 mm-4.0 mm.   The depth dimension of the concave portion is equal to or less than the plate thickness dimension of one of the overlapping portions of the strip-shaped body including the concave portion, and the height dimension of the convex portion is the other of the strip-shaped body including the convex portion. The manufacturing method of the metal cylinder as described in any one of Claims 1-10 made into the plate | board thickness dimension of an overlapping part.

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