JP2007203357A - Expanding die, pail can and method for producing pail can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expanding die which reduces the generation of abrasions to the inside face of a cylindrical body in expander working compared with the conventional case by a simple method; to provide a method for producing a pail can; and to provide a pail can. <P>SOLUTION: In the expanding die 101 having segments 102 radially opening and performing the diameter widening of a cylindrical body 51, the circular face 102a of each segment is formed in such a manner that, when the inside face 51a of the cylindrical body before diameter widening is contacted with the circumferential face of the expanding die 101 in a non-pressed state, the circumferential face forms complete roundness. Thus, the phenomenon that the diameters of both the edge parts in each segment are widened as the inside face is rubbed is prevented, and the generation of abrasions to the inside face can be reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an expanded mold used for the manufacture of a pail can defined in JIS (Japanese Industrial Standards) Z1620 (1995), a method for manufacturing a pail can using the expanded mold, and a manufacturing process using the expanded mold. Related to the pail can.

As shown in the above JIS Z 1620 and as shown in FIG. 12, 18 liter and 20 liter containers provided with a base plate 53 and a handle 54 for the pail can body 52 are generally called pail cans 50. The pail can 50 is roughly classified into a taper type that is tapered from the center to the bottom in the axial direction and a straight type (including a neck-in type) that is not tapered.
In such a pail can, tin-free steel (sometimes referred to as TFS) defined in JIS G 3315 or tin plate defined in JIS G 3303 is used for the can material. These cans are first rolled into a cylindrical shape, and a lap portion at the end of a thin steel plate in the circumferential direction is mash seam welded to form a cylindrical body before diameter expansion. By placing an expanding mold inside the cylindrical body in the initial state before such diameter expansion, the cylindrical body is expanded in diameter by pressing the cylindrical body from the inside to the outside with the expanding mold. The pail can body 52 is molded. The tapered type and the straight type are selected depending on the expanded shape. In some cases, the inner surface of the cylindrical body is coated with a synthetic resin before being processed by the above expander.

  The above expander processing will be described with reference to the drawings. The expander processing is performed by an expander 10 that includes an expand mold 1 as shown in FIG. 7 and has a configuration as shown in FIG. The expand mold 1 has a substantially cylindrical shape as a whole, and has a plurality of segments 2 each having an arc surface 2a divided along the circumferential direction 1a of the cylindrical shape. Therefore, the segment 2 is each member made up of a substantially sectoral column divided into, for example, 16 parts around the central axis of the expanding mold 1. FIG. 7 is a schematic diagram of the expanding mold 1, and the number of segments does not correspond to the actual product.

  As shown in FIG. 8, the expander 10 includes the above-described expandable mold 1, and a drive shaft 11 that engages with the expandable mold 1 within the expandable mold 1 and is movable along the axial direction 1 c of the expandable mold 1. . The drive shaft 11 has a wedge-shaped member 11a, and a taper portion 2b that engages with the wedge-shaped member 11a is formed in the expanding mold 1. Therefore, the expander 10 moves the drive shaft 11 in the axial direction 1c to change the engagement state between the wedge-shaped member 11a and the tapered portion 2b. The segment 2 can be deformed from a closed state to a radially open state, and conversely, from an open state to a closed state.

In the above-described expander process for producing a pail can body portion molded in the expanded state after the diameter expansion from the cylindrical body in the initial state before the diameter expansion, the expanded mold 1 in the closed state is The expanding mold 1 and the cylindrical body are arranged so as to be located inside. Then, as described above, the inner surface of the cylindrical body is pressed in the diametrical direction by moving the drive shaft 11 and moving each segment 2 radially to open the expanding die 1. Thus, the diameter of the cylindrical body is increased, and the pail can body portion is molded.
And a base plate and a handle are fixed with respect to the pail can body part shape | molded in the diameter-expanded state in this way, and a top plate etc. may be attached. In this way, a pail can 50 as shown in FIG. 12 is manufactured.
In addition, although the appropriate prior art document disclosed regarding the said diameter expansion operation | movement in manufacture of a pail can cannot be found, there exists description, for example in patent document 1 regarding diameter expansion operation | movement of can trunk parts, such as a drink can.
Japanese Patent Application Laid-Open No. 2004-289881

As described above, the size and the like of the pail can are defined in JIS Z 1620. Further, since the pail can body portion 52 is used as a body portion of a pail can as a product, when forming the cylindrical body into the pail can body portion, the condition as a body portion of the pail can as a product In order to satisfy the above, it is preferable to adjust the finished state including the prescribed dimensions. From this point of view, in the conventional expander 10 described above, as shown in FIG. 9, in the pail can body portion 52 molded in the expanded state after the expansion, that is, each segment 2 of the expanded mold 1 is radial. In an expanded state, the arc surface 2a of each segment 2 is formed so that the entire peripheral surface 1b of the expand mold 1 including the arc surface 2a of each segment 2 intermittently present on the circumference forms a perfect circle. The arc surface 2a of each segment 2 is formed with a radius that is the curvature. Specifically, since the inner diameter of the pail can body portion 52 molded in the expanded diameter state after the diameter expansion is defined as φ278 mm, the arc surface 2 a of each segment 2 is formed with a radius of curvature of 139 mm. It had been. For the sake of explanation, a radius of 139 mm is assumed to be a radius R3.
FIG. 9 is a schematic diagram of the expandable mold 1, and the number of segments does not correspond to the actual product.

  On the other hand, the inner diameter of the cylindrical body before diameter expansion is φ270 mm, that is, a radius of 135 mm. For the sake of explanation, a radius of 135 mm is assumed to be a radius R0. Further, as described above, the expanded mold 1 is inserted into the inside of the cylindrical body with each segment 2 closed, and then each segment 2 is opened. As described above, the radius of the inner surface 51a of the cylindrical body 51 is R0, that is, 135 mm with respect to the arc surface 2a formed with a radius R3, that is, a radius of curvature of 139 mm, and the inner surface 51a is more than the arc surface 2a. Is also a small circle. Therefore, when each segment 2 is opened and when the arcuate surface 2a of each segment 2 comes into contact with the inner surface of the cylindrical body, the non-pressed state is microscopically represented, as shown in FIG. Both edge portions 2c of 2a first come into contact with the inner surface 51a of the cylindrical body 51. Then, as each segment 2 is further opened, both edges 2c of the arcuate surface 2a of each segment 2 expand the diameter of the cylindrical body 51 while rubbing the inner surface 51a of the cylindrical body 51. Finally, as shown in FIG. 9, the entire arc surface 2 a of each segment 2 is in contact with the inner surface 51 a of the cylindrical body 51, and the pail can body portion 52 having an enlarged diameter is molded. For easy understanding, FIG. 10 shows the relationship between the arcuate surface 2a and the inner surface 51a exaggerated from the actual state.

In the conventional expander 10 having the above-described configuration, the following problems occur.
That is, as described above, the both edges 2c of the circular arc surface 2a expand the diameter of the cylindrical body 51 while rubbing the inner surface 51a of the cylindrical body 51. Therefore, the inner surface 52a of the pail can body 52 in the expanded diameter state includes: As shown in FIG. 11, scratches 53 often occur. Scratches 53 frequently occur on the arc surface 2a of each segment 2 in the inner surface 52a, particularly where the two edges 2c abut. Further, since the cylindrical body 51 contracts in the axial direction as the diameter increases, many scratches 53 are generated at both ends in the axial direction of the pail can body portion 52, particularly near the end portion on the top plate side of the product. . Such an abrasion 53 on the inner surface 52a is not preferable in appearance, and there is a problem that the commercial value of the pail can is lowered.

  In order to prevent the generation of the scratch 53, for example, a method of applying a lubricant to the inner surface 51a of the cylindrical body 51 when expanding the diameter is conceivable. It is not a good idea from the pail can industry.

Further, as described above, since the friction amount of both edges 2c of the arc surface 2a is increased, the arc surface 2a of each segment 2 is also damaged. The occurrence of scratches on the arcuate surface 2a has a problem that it leads to a shortened life of the expanding mold 1. On the other hand, in the case of the cylindrical body 51 in which the inner surface 51a of the cylindrical body 51 is coated with a synthetic resin depending on can applications or customer requirements, the friction between the arc surface 2a and the inner surface 51a is reduced. It becomes difficult to occur. Further, since the tin material has self-lubricating properties, the scratch 53 is relatively less likely to occur even when the tin material is used for the can material.
However, in the expanded mold 1 having a scratch on the arc surface 2a, the scratch 53 is generated on the inner surface 51a of the cylindrical body 51 even if the cylindrical body 51 is coated with synthetic resin. Further, the scratches on the arc surface 2a of each segment 2 increase the friction between the arc surface 2a and the inner surface 51a of the cylindrical body 51 to accelerate the generation of the scratch 53, and when the can material is the above tin-free steel. There is a problem that the surface plating is scraped and the fine particles adhere to the arc surface 2a of each segment 2 to accelerate the generation of the scratch 53. The above-described matters such as the application of lubricant to the inner surface 51a of the cylindrical body 51, the synthetic resin coating, and the selection of the can material are made according to the request of the customer side, and to prevent the generation of the scratch 53. This is not a matter that can be changed on the pail can manufacturer's side.

  In addition, in order to reduce the occurrence of scratches on the arc surface 2a of each segment 2, the material of the segment 2 is improved, for example, hard chrome plating, Teflon (registered trademark) treatment, nitriding treatment, titanium treatment, etc. Although the improvement of the slipperiness and wear resistance of the arc surface 2a is not achieved, satisfactory results have not yet been obtained.

  The present invention has been made in order to solve the above-described problems, and an expanded type, the expanded type, which reduces the occurrence of scratches on the inner surface of a pail can body part in an expander process by a simple method. The purpose of the present invention is to provide a method for manufacturing a pail can utilizing the above-described method, and a pail can manufactured by the method.

In order to achieve the above object, the present invention is configured as follows.
That is, the expandable mold according to the first aspect of the present invention has a substantially cylindrical shape as a whole, has a plurality of segments having arc surfaces divided in the circumferential direction, and is in an initial state before diameter expansion. Pale can body part which is disposed inside and expands each of the segments radially along the diameter direction of the cylindrical body and presses the inner surface of the cylindrical body to expand the diameter of the cylindrical body. In the expanded mold to be molded into
A segment having a circular arc surface with the expanded peripheral surface being a perfect circle in a state where the circular arc surface of each segment is in non-pressing contact with the inner surface of the cylindrical body in the initial state. And

  The arc surface of each segment can be formed with the same radius as the inner surface of the cylindrical body in the initial state and with a uniform radius in the circumferential direction.

Furthermore, the expanded mold according to the second aspect of the present invention has a substantially cylindrical shape as a whole, has a plurality of segments having arc surfaces divided in the circumferential direction, and is in an initial state before diameter expansion. A pail can body which is disposed inside the body, radially expands each segment along the diameter direction of the cylinder and presses the inner surface of the cylinder, thereby expanding the diameter of the cylinder and expanding the diameter of the cylinder. In the expanded mold to be molded into the part,
The arc surface of each of the segments is formed with a first radius at both edge portions of the segment in the circumferential direction and formed at a second radius smaller than the first radius. A segment center part sandwiched between edges,
It is characterized by that.

  In the second aspect, the first radius is the same radius as the radius forming the inner surface of the cylindrical body in the initial state or the radius forming the inner surface of the pail can body portion in the expanded diameter state. May have the same radius.

  In the first aspect and the second aspect, the arc surface of the segment may have an improved treatment layer that favorably enlarges the diameter of the cylindrical body.

  Moreover, the pail can of the 3rd aspect of this invention was equipped with the pail can body part shape | molded by the expand type | mold as described in the said 1st aspect or the said 2nd aspect.

  Moreover, the method for producing a pail can according to the fourth aspect of the present invention is to expand the cylindrical body in an initial state before the diameter expansion using the expand mold according to the first aspect or the second aspect. The pail can is manufactured by expanding the diameter of the pail can body.

  Conventionally, when each expanded type segment is opened in the expanded state after diameter expansion, the above arc surface is formed with a radius that makes the expanded surface formed by the arc surface of each segment a perfect circle. It was. On the other hand, according to the expanded type of the first aspect, when the expanded type is in the initial state before diameter expansion, the radius at which the expanded peripheral surface formed by the arc surface of each segment becomes a perfect circle The arc surface of each segment is formed. Therefore, the entire surface of the arc surface of each segment comes into contact with the inner surface of the cylindrical body to be expanded from the beginning of the expansion, and the diameter expansion operation proceeds. Therefore, during the diameter expansion operation as in the prior art, the phenomenon that the inner surface of the cylindrical body is scratched by friction between both edges of the arc surface of each segment and the inner surface of the cylindrical body is reduced.

  Further, according to the expanded type of the second aspect, the arc surface of the segment has segment both edges formed with a first radius and a segment center formed with a second radius smaller than the first radius. And have. Therefore, the segment center portion forms an arc surface protruding in the diameter direction of the cylindrical body from the arc surface formed at both edge portions of the segment. Therefore, the diameter expansion operation is executed while the central portion of the segment presses the inner surface of the cylindrical body in the diameter direction. Therefore, during the diameter expansion operation as in the prior art, the phenomenon that the inner surface of the cylindrical body is scratched by friction between both edges of the arc surface of each segment and the inner surface of the cylindrical body is reduced.

  In addition, according to the pail can of the third aspect, since the pail can body portion is molded using the expanded mold according to the first aspect or the second aspect described above, the scratches on the inner surface of the pail can as a product are conventionally caused. Compared to, it can be reduced.

  Further, according to the method for manufacturing a pail can according to the fourth aspect, the basic molding operation relating to the pail can body part is not different from the conventional one, and the changed part forms an arc surface of each expanded type segment. The radius to be Therefore, it is possible to reduce the occurrence of scratches on the inner surface of the cylindrical body by a simpler method than in the prior art.

  An expanded mold which is an embodiment of the present invention, a method for manufacturing a pail can using the expanded mold, and a pail can manufactured using the expanded mold will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

The expanding mold in the present embodiment has basically the same structure and function as the above-described expanding mold 1, and a split metal for molding the pail can body portion 152 in the manufacturing process of the pail can 150 shown in FIG. It is a type. The pail can 150 is a pail having a pail can body portion 152 formed by the expanding mold according to the present embodiment as will be described below, and has an external appearance (excluding the inner surface of the pail can body portion). And, there is no difference in function from the pail can 50 shown in FIG.
The expand type in the present embodiment will be specifically described with reference to FIG. The expanding mold 101 according to the present embodiment has a substantially cylindrical shape as a whole, and includes a plurality of segments 102 each having an arc surface 102a divided along the circumferential direction 101a of the cylindrical shape. Therefore, the segment 102 is each member divided into, for example, 16 parts around the central axis of the expanding mold 101. FIG. 2 is a schematic diagram of the expanding mold 101, and the number of segments does not correspond to the actual product.

  The expanding mold 101 configured as described above can be attached in place of the expanding mold 1 in the conventional expander 10 shown in FIG. Therefore, the components of the expander 10 excluding the expandable mold 1 can be used with the conventional configuration. Therefore, although detailed description regarding the expander 10 to which the expander mold 101 is attached is omitted here, the expander 10 to which the expander mold 101 is attached is a cylinder body with the expander mold 101 disposed inside the cylinder body 51. By expanding each segment 102 radially along the diameter direction 51b of 51, the cylindrical body 51 can be expanded in diameter and molded into a pail can body portion 152 in an expanded state.

On the other hand, the expanding mold 101 is different from the conventional expanding mold 1 in the following points.
That is, as described above with reference to FIG. 9, in the conventional expanding mold 1, the arc surface 2 a of each segment 2 is a perfect circle when the pail can body portion 52 in the expanded state after the expansion is molded. In other words, the radius R3 is formed. On the other hand, in the expanded mold 101 of the present embodiment, as shown in FIG. 1, the arc surface 102a of each segment 102 contacts the inner surface 51a of the cylindrical body 51 in the initial state before the diameter expansion, and each segment Each segment 102 has an arc surface 102a in which the peripheral surface 101b of the expanding mold 101 is a perfect circle in a non-pressed state where the inner surface 51a is not yet pressed in the diameter direction 51b of the cylindrical body 51. In the state where the arc surface 102a of each segment 102 is in contact with the inner surface 51a of the cylindrical body 51 in the initial state in the non-pressed state, each segment 102 is in a state of being slightly expanded radially, The peripheral surface 101b of the expandable mold 101 means the entire peripheral surface of the expandable mold 1 including the arc surface 102a of each segment 102 that exists intermittently.

The arc surface 102a of each segment 102 will be described in more detail. The arc surface 102a of each segment 102 has the same radius as that forming the inner surface 51a of the cylindrical body 51 in the initial state, and the circumferential direction 101a of the expand mold 101. 1 and having a radius R0 as shown in FIG. Specifically, as described above, the inner diameter of the cylindrical body 51 before diameter expansion is φ270 mm, that is, a radius of 135 mm. Therefore, the arc surface 102a of each segment 102 is formed with a radius of 135 mm, that is, the radius R0 = 135 mm.
FIG. 1 schematically shows the expandable mold 101, and the number of segments does not correspond to the actual product.

The expand mold 101 having such a configuration is attached to the expander 10 as described above, and performs molding from the cylindrical body 51 in the initial state to the pail can body portion 152 in the expanded diameter state. The molding operation will be described below.
That is, each segment 102 of the expanding mold 101 is formed by the change in the engagement state between the wedge-shaped member 11a and the tapered portion 2b due to the movement of the drive shaft 11 provided in the expander 10 in the axial direction 1c. It moves radially along the diameter direction 51b. Therefore, each segment 102 that has been in contact with the inner surface 51 a of the cylindrical body 51 in the initial state on the entire surface of the circular arc surface 102 a expands the diameter of the cylindrical body 51. In the diameter expansion operation using the expanding mold 101 of the present embodiment, the entire surface of the circular arc surface 102a is in contact with the inner surface 51a of the cylindrical body 51 in the initial state as described above. The phenomenon that the both edges 2c expand the diameter while rubbing the inner surface 51a does not occur. Therefore, even if the cylindrical body 51 is not subjected to the above-described synthetic resin coating on the inner surface 51a of the cylindrical body 51, a conventional scratch 53 is generated on the inner surface 51a of the cylindrical body 51 during the diameter expansion operation. Can be reduced. Of course, in order to reduce the generation of the scratch 53, the lubricant 53 is applied to the inner surface 51a of the base cylindrical body 51, and the lubricant is washed and removed after the diameter is expanded. Generation can be sufficiently reduced.
It should be noted that this embodiment does not limit or prohibit the application of the lubricant, but it is clear that the generation of the scratches 53 can be further reduced by applying the lubricant.

As described above, the inner diameter of the pail can body 152 molded into the expanded state after the expansion is φ278 mm and the radius is 139 mm (radius R3). On the other hand, as described above, the radius of the arc surface 102a of the segment 102 of the expandable mold 101 of the present embodiment is 135 mm (radius R0). Therefore, in the pail can body portion 152 in the diameter-expanded state, the arc surface 102a of each segment 102 formed with a radius of 135 mm is compared with the true inner peripheral surface 1521 with the radius of 139 mm as shown in FIG. The entire surface is not in contact, and both edge portions 1021 of the arc surface 102a are not in contact. Therefore, microscopically, the inner surface 152a of the pail can body portion 152 molded in the expanded diameter state is not molded into the true circle of the true inner peripheral surface 1521 having a radius of 139 mm as shown in FIG. It is thought that it becomes the shape of the substantially regular polygon which consists of the surrounding surface. FIG. 3 exaggerates the relationship between the arcuate surface 102a of the segment 102 and the true inner peripheral surface 1521 for the sake of easy understanding.
However, in reality, even if the diameter of the cylindrical body 51 is increased on the arc surface 102a of each segment 102 formed with a radius of 135 mm, the pail can body does not have any problem in terms of JIS regulations and products. Applicant has confirmed that part 152 can be finished.

  As described above, according to the expandable mold 101 of the present embodiment, it is possible to reduce the occurrence of scratches on the inner surface of the pail can body portion by a very simple configuration change compared to the conventional expandable mold 1. Can do. Further, the arc surface 102a of each segment 102 has a simple configuration as compared with the configuration in the modified example described below, and is advantageous in cost as compared with the following modified example.

Below, the expand type | mold of 2nd Embodiment is demonstrated.
As described above, the arc surface 102a of each segment 102 of the expanding mold 101 is formed with a uniform radius in the circumferential direction 101a. On the other hand, even when the circular arc surface 2a is formed with a radius 139 mm of the radius R3 as in the conventional segment 2, both edges 2c of each segment 2 are in contact with the inner surface 51a of the cylindrical body 51 in the initial state. It is considered that the generation of the scratches 53 can be reduced by configuring so as not to contact.
As an example of the “configuration in which both edge portions 2c do not contact”, there is a configuration shown in FIG. FIG. 4 shows one of the segments 106 constituting the expandable mold 105 of the second embodiment. The expand mold 105 is a split mold that can be attached to the expander 10 and molds the cylindrical body 51 in the initial state into a pail can body portion 152 in an enlarged diameter state, similarly to the expand mold 101 described above.

  The arc surface 106a of each segment 106 is formed with a segment radius 106a in the circumferential direction 105a of the expand mold 105 and a second radius R2 smaller than the first radius R1. , And a segment central portion 106d sandwiched between both edge portions 106c in the circumferential direction 105a. By adopting a configuration having the relationship between the first radius R1 and the second radius R2, the segment central portion 106d includes both segment edge portions 106c and has a uniform radius in the circumferential direction 105a as shown in FIG. An arcuate surface 106e that protrudes in the diameter direction 51b of the cylindrical body 51 from the arcuate surface 106a to be formed is formed.

  As described above, in order to reduce the generation of the scratch 53, it is only necessary to have a configuration in which both edge portions 106c of each segment 106 do not contact the inner surface 51a of the cylindrical body 51 in the initial state. For example, the first radius R1 is not particularly defined, but from the practical viewpoint of forming the pail can body portion 152 in an expanded state, for example, the radius R0 that forms the inner surface 51a of the cylindrical body 51 in the initial state, that is, It is preferable that the radius is 135 mm or the same radius as the radius R3 that forms the inner surface 152a of the pail can body portion 152 in the expanded diameter state, that is, the radius 139 mm.

  As an example, the first radius R1 that forms the segment edges 106c of the arc surface 106a of each segment 106 is a radius R0, that is, a radius of 135 mm, and the second radius that forms the segment central portion 106d is 5 mm from the radius 135 mm. The reduced radius can be 130 mm.

  The ratio of the arc surface 106e of the segment central portion 106d to the arc surface 106a of each segment 106 will be described. From the viewpoint that each segment 106 has a configuration in which both edge portions 106c of each segment 106 do not come into contact with the inner surface 51a of the cylindrical body 51 in the initial state, it is related to the first radius. However, the ratio of the arcuate surface 106e is basically not particularly defined, but from the practical viewpoint of forming the pail can body portion 152 in an expanded state, for example, as shown in FIG. A ratio such that the arc surface 106e of the central portion 106d of the segment exists so as to correspond to an angle corresponding to 2θ in the central portion of the central angle divided into four or approximately 2θ is preferable.

  As described above, each segment 106 is formed with the segment central portion 106d having the arc surface 106e projecting in the diameter direction 51b of the cylindrical body 51 from the arc surface 106a. The segment central portion 106d abuts on the inner surface 51a of the cylindrical body 51 in the state to expand the diameter of the cylindrical body 51 and is molded into the pail can body portion 152 in the expanded diameter state. During the diameter expansion operation, the segment central portion 106d always contacts the inner surface 51a of the cylindrical body 51 to expand the diameter of the cylindrical body 51. Therefore, the phenomenon that the scratches 53 are generated on the inner surface 51a of the cylindrical body 51 due to the friction of both edge portions 2c of the circular arc surface 2a during the diameter expansion operation as in the prior art is reduced.

  As described above, according to the expanding dies 101 and 105 of this embodiment, the generation of the scratch 53 on the inner surface 51a of the cylindrical body 51 due to the diameter expanding operation can be reduced. This also reduces the occurrence of scratches on the arcuate surfaces 102a, 106a of the segments 102, 106 of the expanding dies 101, 105. Therefore, the expandable molds 101 and 105 contribute to extending the life of the expandable mold.

Furthermore, it is preferable that the arc surface 102a of each segment 102 of the expanding mold 101 and the arc surface 106a of each segment 106 of the expanding mold 105 have an improvement processing layer 103 as shown in FIG.
The improvement processing layer 103 is a portion for reducing the occurrence of the scratch 53 as described above on the arc surface 102a of each segment 102 and the arc surface 106a of each segment 106, and favorably expanding the diameter of the cylindrical body 51. . The improvement processing layer 103 is a portion in which the material of the segments 102 and 106 is improved. For example, hard chrome plating, Teflon (registered trademark) processing, nitriding processing, titanium processing, or the like is performed, and the arc surfaces of the segments 102 and 106 are processed. It is a part which improves the slipperiness and wear resistance of 102a and 106a.
By forming such an improved treatment layer 103 on the arcuate surfaces 102a and 106a of the segments 102 and 106, the slipping property and the wear resistance are improved. Owing to the synergistic effect with this configuration, the generation of scratches 53 can be further reduced.

  The base plate 53 and the handle 54 may be fixed to the pail can body portion 152 formed using the expanding molds 101 and 105 configured as described above, and the top plate 55 and the like may be attached. In this way, a pail can 150 as shown in FIG. 6 is manufactured. Compared with the conventional pail can 50, in the pail can 150 in this embodiment, there is little generation | occurrence | production of the abrasion 53 on the inner surface 152a of the pail can body part 152, and the commercial value of a pail can is not reduced.

  The present invention is applicable to an expanding mold used for manufacturing a pail can and a method for manufacturing a pail can using the expanding mold.

It is a top view which shows the expand type | mold of 1st Embodiment of this invention. It is a perspective view of the expand type shown in FIG. It is a figure which shows the state which shape | molded the pail body part by the expand type | mold shown in FIG. It is a top view which shows one of the segments which comprise the expand type | mold of 2nd Embodiment of this invention. It is sectional drawing which shows the state in which the improvement process layer was formed in the expanded segment shown in FIG. It is a perspective view which shows the pail can which has the pail can body part shape | molded by the expand type | mold shown in FIG.1 and FIG.4. It is a perspective view of the conventional expand type. It is a front view which shows the expander which expands a cylindrical body provided with an expand type | mold. It is a top view which shows the conventional expand type | mold. It is a top view which shows the state which the conventional expanded type segment contacted the inner surface of the cylindrical body of an initial state. It is the schematic which shows the abrasion which arose on the inner surface of the cylindrical body by the diameter expansion operation | movement by the conventional expand type | mold. It is a perspective view which shows the pail can which has the pail can body part shape | molded by the conventional expand type | mold.

Explanation of symbols

51 ... Cylindrical body, 51a ... Inner surface, 51b ... Diameter direction,
101 ... Expandable type, 101b ... Surface, 102 ... Segment,
102a ... circular arc surface, 105 ... expanding, 106 ... segment,
106a ... circular arc surface, 106c ... both edges of the segment, 103 ... improvement treatment layer,
150 ... Pail can, 152 ... Pail can body.

Claims (7)

The overall shape is substantially cylindrical, has a plurality of segments having arcuate surfaces divided in the circumferential direction, and is disposed inside a cylindrical body (51) in an initial state before diameter expansion. An expand that radially expands each of the segments along the diameter direction (51b) and presses the inner surface (51a) of the cylindrical body to expand the cylindrical body to form a pail can body portion in an expanded state. In the mold,
An arcuate surface (102a) in which the peripheral surface (101b) of the expanded mold (101) is a perfect circle when the arcuate surface of each segment is in non-pressing contact with the inner surface of the cylindrical body in the initial state An expanded type comprising a segment (102) having   The arc surface of each segment is formed with a radius (R0) that is the same as a radius that forms the inner surface of the cylindrical body in the initial state and that is uniform in the circumferential direction (R0). Expand type. The overall shape is substantially cylindrical, has a plurality of segments having arcuate surfaces divided in the circumferential direction, and is disposed inside a cylindrical body (51) in an initial state before diameter expansion. An expand that radially expands each of the segments along the diameter direction (51b) and presses the inner surface (51a) of the cylindrical body to expand the cylindrical body to form a pail can body portion in an expanded state. In the mold,
The arc surface (106a) of each segment (106) has a segment radius (106c) in the circumferential direction formed by a first radius (R1) and a second radius (106) that is smaller than the first radius. A segment center portion (106d) sandwiched between both edge portions of the segment in the circumferential direction, formed in R2).
Expand type characterized by that.   The first radius is the same as the radius (R0) that forms the inner surface of the cylindrical body in the initial state, or the same radius as the radius (R3) that forms the inner surface of the pail can body in the expanded diameter state. The expanded mold according to claim 3, which has a radius of   The expand type according to any one of claims 1 to 4, wherein the arc surface of the segment has an improvement treatment layer (103) for favorably expanding the diameter of the cylindrical body.   A pail can comprising a pail can body (152) molded with the expandable mold (101, 105) according to any one of claims 1 to 5. Using the expandable die (101, 105) according to any one of claims 1 to 5, the pail can body portion (152) in an expanded state of the cylindrical body (51) in an initial state before being expanded in a cylindrical shape. A pail can manufacturing method characterized in that the pail can (150) is manufactured by expanding the diameter of the pail.

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