A collar shaper and its integral forming process

Abstract

The application discloses a collar shaper and a whole forming process thereof, and relates to the technical field of collar shapers. The collar shaper avoids the need for a large number of complex mathematical model establishment and solution by taking a non-rectangular plate as a raw material, simplifies production operation, improves work efficiency, can change parabolic focal parameters and conical development surface sizes according to actual production line requirements, realizes rapid design modeling of the collar shaper, and simultaneously realizes natural bending of an unconstrained shoulder curved surface along an intersection curve of a parabola, realizes whole forming of the collar shaper, and has high forming efficiency, good quality, low cost, and high universality.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of collar shaper, in particular to a collar shaper and an overall forming process thereof. BACKGROUND

[0002] The collar shaper is a key part of the forming, filling, sealing and packaging machine, which is used to fold and form the flat roll packaging material into a cylindrical packaging bag through the collar shaper, and then fill the material. It has a direct impact on the style, speed and product quality of the packaging. The collar shaper generally includes a shoulder curved surface, a back plane and a cylindrical (cylinder, elliptical cylinder, prism, etc.) material barrel. In order to ensure that the packaging material is evenly stressed and has no compression wrinkles and extension damage during the folding process, the packaging material should be as close as possible to the back plane and the shoulder curved surface through the collar shaper. Therefore, the shoulder curved surface of the collar shaper must be a developable curved surface.

[0003] The collar shaper disclosed in the application CN112026261A is a series of collar shapers without a back plane, and the shoulder curved surface thereof is a cylindrical surface, which does not involve the forming process of the collar shaper. The conventional processing and manufacturing methods of the collar shaper mainly include welding of sheet metal, machining by multi-axis milling machining center, and precision casting method. The welding of sheet metal is the most commonly used processing method at present, but the shaper made by this process is difficult to succeed at one time and needs to be cut, bent, welded, polished and corrected. The bending and welding require high requirements for the tooling and the experience of workers. In order to improve the efficiency and consistency of the forming, some special devices are often needed, such as the automatic bending machine for the curved surface of the collar shaper disclosed in the application CN111889548A, the automatic welding forming method for the collar shaper disclosed in the application patent CN113770579B, and the welding positioning tooling and positioning method for the collar shaper disclosed in the application patent CN113770580B. However, in order to ensure smooth transition at the connection of the sheet metal, the sheet metal needs to be polished several times before it can be used, which is very low in production efficiency and is not suitable for mass production. The multi-axis machining center has an advantage in processing high-precision parts with complex curved surface shape. Although it can ensure the processing precision of the collar shaper, it is necessary to accurately model each part of the collar shaper first, and the clamping process is relatively complicated when machining the curved surface, which requires high professional and technical requirements for the workers, and also increases the production cost. The process of the precision casting method is relatively complex, and in order to meet the requirements of the surface roughness and other shape and position tolerances of the collar shaper, this method also requires high cost.

[0004] In order to ensure the precision and quality of the collar former during forming manufacturing, it is necessary to establish a mathematical model for the shoulder curved surface of the collar former obtained by folding a rectangular plane and the boundary curve of the shoulder curved surface and the back plane from the perspective of spatial analytic geometry, differential geometry and the like, the derivation process is complex, the solving difficulty is large, which leads to the need for simplification in actual application, the forming effect error is large, and repeated trimming is needed to meet the production requirements, in addition, the collar former formed by the rectangular plane, the shape feature sizes are mutually influenced and constrained, the design method of the collar former with different barrel shapes does not have universality, therefore, a collar former and its overall forming process are provided to solve the above problems. SUMMARY

[0005] PROBLEMS TO BE SOLVED

[0006] In view of the deficiencies of the prior art, the collar former and its overall forming process are provided to solve the problems of the need to establish a large number of mathematical models, the complex derivation process, the large solving difficulty, the large forming effect error in actual application, the need for repeated trimming to meet the production requirements, and the lack of universality.

[0007] TECHNICAL SCHEME

[0008] To achieve the above purpose, the following technical scheme is adopted: a collar former, comprising a curved surface whole, the curved surface whole comprising a first curved surface and a second curved surface, the intersection of the first curved surface and the second curved surface being a parabola, the focus of the parabola being located in the first curved surface, the focus of the parabola and the vertex of the second curved surface coinciding, the angle between the generatrix of the first curved surface and the tangent at a point on the parabola being equal to the angle between the generatrix of the second curved surface and the tangent at the same point on the parabola.

[0009] Further, the curved surface whole is a non-rectangular planar plate, the plate thickness is 0.2-2mm, and the plate is a low-strength metal material capable of elastic-plastic deformation.

[0010] Further, the first curved surface is a cylindrical development surface, and the second curved surface is a first conical development surface.

[0011] Further, the second curved surface comprises a first conical development surface and a first back plane, and the first conical development surface is arranged on both sides of the first back plane.

[0012] Further, the first curved surface comprises a side wall plane development surface and a rounded cylindrical surface development surface, the side wall plane development surface and the rounded cylindrical surface development surface are arranged at intervals, the second curved surface comprises a second conical development surface and a second back plane development surface, and the second conical development surface and the second back plane development surface are arranged at intervals, and a rounding die is movably arranged outside the first curved surface.

[0013] Further, the connecting line between the side wall plane development surface and the second back plane development surface is a straight line, and the connecting line between the round corner cylindrical surface development surface and the second conical surface development surface is a parabola.

[0014] Further, the roll forming die comprises an upper die and a lower die, and the upper die and the lower die are both half rectangles.

[0015] The application further provides a whole forming process of the collar former, comprising the following steps:

[0016] S1, selecting a plate of low-strength metal material with an elastic-plastic deformation thickness of 0.2-2 mm, cutting the plate to form a non-rectangular plane shape;

[0017] S2, pre-bending the plate through a bending device and a bending knife, and then performing roll forming operation to control the forming of the barrel, so as to form the collar former.

[0018] Further, the barrel is cylindrical, and the S2 specifically comprises the following steps:

[0019] S211, bending along the connecting line between the cylindrical surface and the first conical surface, i.e. bending along a parabola, to bend the plane plate and form a bending line to separate the cylindrical surface and the first conical surface in the plane plate;

[0020] S212, then only the cylindrical surface is subjected to roll forming treatment, a multi-step segmented arc bending is implemented to achieve the roll forming effect, or an upper die and a lower die with a half cylindrical surface feature are used to make the cylindrical surface pre-formed into a U-shaped bend under pressure, and then the U-shaped bend is further subjected to air pressure roll forming into a cylinder, while the cylindrical surface is subjected to roll forming, the first conical surface is bent into a conical surface, i.e. the collar former of the cylindrical barrel is formed;

[0021] S213, according to requirements, the cylindrical barrel collar former without a back plane can be obtained through further flattening operation to obtain a cylindrical barrel collar former with a first back plane.

[0022] Further, the barrel is non-cylindrical, and the S2 further comprises the following steps:

[0023] S221, bending the plane plate along the intersection line between the left side and the right side of the plane plate to form a bending line, pre-bending the intersection line between the round corner cylindrical surface development surface and the side wall plane development surface on the same side, and then pre-bending the intersection line between the second conical surface development surface and the second back plane development surface on the other side of the plane plate;

[0024] S222, the circular cylindrical surface development face is bent in an arc, and then the first curved surface after the pre-bending is further air-pressured and coiled into a column shape in the upper die and the lower die with semi-rectangular characteristics, so that the collar former of the rectangular barrel is formed.

[0025] Advantages

[0026] The present application has the following advantages:

[0027] (1), the collar former, by taking a non-rectangular sheet as a raw material, avoids a large number of complex mathematical model establishment and solution for the collar former, especially for the shoulder curved surface and the intersection curve between the shoulder curved surface and the back plane, thereby simplifying production operation, avoiding large forming effect error, repeatedly modifying, and improving work efficiency.

[0028] (2), the overall forming process of the collar former, by using the developable curved surface shape forming sheet composed of the cylindrical development face and the conical development face, has a parabola intersection line, can change the parabola focal parameter and the conical development face size according to actual production line requirements, such as the included angle between the back surface and the vertical direction, the back surface length, and realize rapid design modeling of the collar former.

[0029] (3), the overall forming process of the collar former, due to the dynamic constraint relationship of the developable curved surfaces on both sides of the bending line, by coiling the cylindrical barrel part, the unconstrained shoulder curved surface is naturally bent along the intersection curve which is a parabola, the overall forming of the collar former is realized, the forming efficiency is high, the quality is good, the cost is low, and different columnar collar formers can be obtained by modifying the intersection curve according to the development face of the cylindrical barrel collar former, with the aid of similar coiling overall forming process, the versatility is high.

[0030] Of course, any product implementing the present application does not necessarily need to achieve all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic view of the unfolded cylindrical barrel collar former in embodiment 1 of the present application.

[0032] Figure 2 It is a structure schematic view of the front view of the cylindrical barrel collar former in embodiment 1 of the present application.

[0033] Figure 3 It is a structure schematic view of the left view of the cylindrical barrel collar former in embodiment 1 of the present application.

[0034] Figure 4 It is a structure schematic view of the first back plane in embodiment 1 of the present application.

[0035] Figure 5It is a schematic view of the unfolded rectangular barrel collar former in the embodiment 2 of the present application.

[0036] Figure 6 It is a structural schematic view of the roll molding die in the embodiment 2 of the present application.

[0037] Figure 7 It is a structural schematic view of the front view of the rectangular barrel collar former in the embodiment 2 of the present application.

[0038] Figure 8 It is a schematic view of the rectangular plane without bending.

[0039] Figure 9 It is a schematic view of the rectangular plane bending along the curve to form the concave-convex curved surface feature.

[0040] In the figure, 1, the whole curved surface; 101, the first curved surface; 102, the second curved surface; 2, the cylindrical unfolded surface; 3, the first conical unfolded surface; 4, the first back plane; 5, the side wall plane unfolded surface; 6, the rounded cylindrical surface unfolded surface; 7, the second back plane unfolded surface; 8, the second conical unfolded surface; 9, the roll molding die; 901, the upper die; 902, the lower die. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] In the description of the present application, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "periphery" and the like indicate the orientation or positional relationship, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the components or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0043] Embodiment 1

[0044] Please refer to Figures 1-4 , Figure 8 and Figure 9The embodiment of the present application provides a technical scheme: a collar former, comprising a curved surface whole 1, the curved surface whole 1 comprising a first curved surface 101 and a second curved surface 102, the intersection of the first curved surface 101 and the second curved surface 102 being a parabola, the focus of the parabola being located in the first curved surface 101, the focus of the parabola and the vertex of the second curved surface 102 being coincident, and the included angle between the generatrix of the first curved surface 101 and the tangent at a point on the parabola being equal to the included angle between the generatrix of the second curved surface 102 and the tangent at the same point on the parabola.

[0045] Specifically, the curved surface whole 1 is a non-rectangular planar plate, the thickness of the plate is 0.2-2 mm, and the plate is a low-strength metal material capable of elastic-plastic deformation.

[0046] In the embodiment, the developable surface theory shows that after an ideal plane without thickness and not stretchable is bent along a curve, two developable surfaces with the same average curvature and opposite signs, i.e., a concave surface and a convex surface, are formed on both sides of the bending line, and in the bending process, the curvature size and the bending angle are in one-to-one correspondence, in addition, when the generatrices of the two developable surfaces are collinear before bending, the bending line is located in a spatial plane during the entire bending process, i.e., the intersection of the two developable surfaces and the bending line is a spatial plane curve, and after a rectangular plane 1 without thickness and not stretchable is bent along a curve s, two developable surfaces S1 and S2 with average curvatures k1 and k2 are formed, wherein k1=-k2, the surfaces S1 and S2 are connected by a spatial plane curve s', the included angle between the generatrices of the two surfaces is γ, and the generatrices of the two surfaces are located on the same straight line BB' before bending, since the surface is not stretchable, the surface curvature and the bending angle are dynamically constrained during the bending process, and when the generatrices of the two developable surfaces have the same angle with the curve bending line during the bending process, the two developable surfaces have the same dihedral angle along the curve bending line at any time.

[0047] According to the property of the parabola: the tangent at a point on the parabola intersects the directrix at a point, and the perpendicular line of the directrix passing through the tangent point, the tangent line bisects the included angle formed by the focus, the foot and the tangent point, since the cylindrical generatrix is perpendicular to the parabola directrix, and the focus of the parabola is coincident with the vertex of the conical surface, it can be known that the included angle formed by the cylindrical generatrix and the conical generatrix at any point on the intersection of the two parabolas is bisected by the tangent at the point, and thus α=β can be obtained.

[0048] The low-strength metal material capable of elastic-plastic deformation can be bent and rolled, and can avoid breaking, and the parabola focus parameters and the conical developable surface size can be changed according to actual production line requirements, such as the included angle between the back surface and the vertical direction, the back surface length, etc., to realize rapid design and modeling of the collar former.

[0049] Specifically, the first curved surface 101 is a cylindrical developable surface 2, and the second curved surface 102 is a first conical developable surface 3.

[0050] In the embodiment, the cylindrical developing surface 2 is in a cylindrical shape after the rolling operation, and the first conical developing surface 3 is used to form a conical surface.

[0051] Specifically, the second curved surface 102 includes the first conical developing surface 3 and the first back plane 4, and the first conical developing surface 3 is arranged on both sides of the first back plane 4 respectively.

[0052] In the embodiment, the first conical developing surface 3 is flattened to form the first back plane 4 through the flattening operation, which is suitable for different collar forming requirements.

[0053] A whole forming process of a collar former, as shown in Figure 1 includes the following steps:

[0054] S1, selecting a plate of low-strength metal material with a thickness of 0.2-2 mm and capable of elastic-plastic deformation, cutting the plate to form a non-rectangular planar shape;

[0055] S2, pre-bending the plate through a bending device and a bending knife, then rolling the plate, controlling the forming of the barrel, and thus forming the collar former.

[0056] In the embodiment, by taking the non-rectangular plate as the raw material, the establishment and solving of a large number of complex mathematical models for the collar former, especially for the shoulder curved surface and the intersection curve between the shoulder curved surface and the back plane, are avoided. Through pre-bending, the components of the collar former are separated, which facilitates the simultaneous forming of the two developable curved surfaces in the next step, and facilitates the forming operation of only one component of the developing surface in the subsequent step. For the cylindrical barrel collar former, pre-bending is performed at the intersection of the parabolas. For the non-cylindrical barrel collar former, pre-bending is needed at the intersection of the two components and the intersection of the curved surface and the plane in each component. In addition, the part containing the conical surface is opposite to the bending side of the other part.

[0057] The rolling operation is used to form the cylindrical barrel. Under geometric constraints, the barrel is formed at the same time, and the back plane shoulder curved surface and other features are naturally formed. For different shapes of the cylindrical barrel, one-step to multi-step segmented rolling process can be adopted.

[0058] Specifically, the barrel is cylindrical, as shown in Figures 1-4 S2 specifically includes the following steps:

[0059] S211, bending along the connecting line of the cylindrical developing surface 2 and the first conical developing surface 3, i.e. bending along the parabola, bending the planar plate to form a bending line to separate the cylindrical developing surface 2 and the first conical developing surface 3 in the planar plate;

[0060] S212, then only the cylindrical development surface 2 is subjected to the rounding process, and the rounding effect is realized by multi-step segmented arc bending, or the upper and lower molds with semi-cylindrical surface characteristics are used to make the cylindrical development surface 2 pre-formed into a U-shaped bend by pressure instability, and then the U-shaped bend is further air-pressed and rounded into a cylinder, while the cylindrical development surface 2 is rounded, the first conical development surface 3 is bent into a conical surface, thereby forming the collar former of the cylindrical barrel;

[0061] S213, according to the requirements, the cylindrical barrel collar former without a back plane can be obtained by further flattening operation to obtain a cylindrical barrel collar former containing a first back plane 4.

[0062] In the embodiment, according to the theory of developable surface, when the planar sheet is bent along the parabola, the cylindrical development surface 2 and the first conical development surface 3 have the same dihedral angle everywhere, the bending tool profile can intersect the parabola on the planar sheet, and the bending tool head has the same thickness along the profile line.

[0063] According to the theory of developable surface, when the planar sheet is bent along the parabola, the average curvature of the cylindrical surface and the conical surface is dynamically constrained by the bending degree, and the average curvature of the cylindrical development surface 2 and the first conical development surface 3 is equal, thereby forming the collar former of the cylindrical barrel, and by flattening the first conical development surface 3, a cylindrical barrel collar former containing a first back plane 4 can be obtained, which is suitable for products with different requirements.

[0064] Embodiment 2

[0065] Please refer to Figures 6-7 , specifically, the first curved surface 101 includes a side wall planar development surface 5 and a rounded cylindrical development surface 6, the side wall planar development surface 5 and the rounded cylindrical development surface 6 are arranged at intervals, the second curved surface 102 includes a second conical development surface 8 and a second back plane development surface 7, the second conical development surface 8 and the second back plane development surface 7 are arranged at intervals, and the first curved surface 101 is externally movably provided with a rounding die 9.

[0066] In the embodiment, the side wall planar development surface 5 and the rounded cylindrical development surface 6 form a rectangular barrel after rounding, the side wall planar development surface 5 and the rounded cylindrical development surface 6 are arranged at intervals for bending at their intersection, the second conical development surface 8 and the second back plane development surface 7 form a conical shape after rounding, the second conical development surface 8 and the second back plane development surface 7 are arranged at intervals for bending at their intersection, and the rounding die 9 is used for rounding the first curved surface 101.

[0067] Specifically, the connecting line of the side wall planar development surface 5 and the second back plane development surface 7 is a straight line, and the connecting line of the rounded cylindrical development surface 6 and the second conical development surface 8 is a parabola.

[0068] In the embodiment, the first curved surface 101 and the second curved surface 102 are separated by a bending line formed by a straight line and a parabola.

[0069] Specifically, the rounding die 9 includes an upper die 901 and a lower die 902, both of which are half-rectangular.

[0070] In the embodiment, the first curved surface 101 is extruded to be cylindrical by the upper die 901 and the lower die 902 arranged outside the first curved surface 101 after bending.

[0071] Specifically, the barrel is non-cylindrical, as shown in Figure 9 As shown, S2 further includes the following steps:

[0072] S221, bend the flat plate along the intersection line on the left and right sides to form a bending line, and pre-bend the intersection line between the rounded cylindrical surface development surface 6 and the side wall flat surface development surface 5 on the same side, and then pre-bend the intersection line between the second conical surface development surface 8 and the second back flat surface development surface 7 on the other side of the flat plate;

[0073] S222, round the arc of each rounded cylindrical surface development surface 6, and then further extrude the first curved surface 101 after pre-bending in the upper die 901 and the lower die 902 with half-rectangular characteristics to be cylindrical, so as to form a collar shaper of a rectangular barrel.

[0074] In the embodiment, the bending line is used to separate the left and right sides of the developable curved surface, and the pre-bending of each part and the cooperation of the upper die 901 and the lower die 902 facilitate the subsequent rounding forming operation. According to the different shapes of the required barrel, the rounding die 9 with different shapes is replaced.

[0075] It should be noted that, in the present document, the terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0076] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and get the best results from the application. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A collar shaper comprising a curved surface unit (1), characterized in that: The whole curve (1) includes a first curve (101) and a second curve (102), the intersection line of the first curve (101) and the second curve (102) is a parabola, the focus of the parabola is located in the first curve (101), the focus of the parabola coincides with the face vertex of the second curve (102), the included angle between the generatrix of the first curve (101) and the tangent at a point on the parabola is equal to the included angle between the generatrix of the second curve (102) and the tangent at the same point on the parabola; The whole curve (1) is a non-rectangular planar plate, the thickness of the plate is 0.2-2mm, and the plate is a low-strength metal material capable of elastic-plastic deformation; The whole forming process of the collar former includes the following steps: S1, selecting a low-strength metal material plate with a thickness of 0.2-2mm capable of elastic-plastic deformation, cutting the plate to form a non-rectangular planar shape; S2, pre-bending the plate through a bending device and a bending knife, then performing a round rolling operation, controlling the forming of the barrel, and thus forming a collar former.

2. A collar shaper as claimed in claim 1, wherein: The first curve (101) is a cylindrical development surface (2), and the second curve (102) is a first conical development surface (3).

3. A collar shaper as claimed in claim 2, wherein: The second curve (102) includes a first conical development surface (3) and a first back plane (4), and the first conical development surface (3) is arranged on both sides of the first back plane (4) respectively.

4. A collar shaper as defined in claim 1, wherein: The first curve (101) includes a side wall plane development surface (5) and a filleted cylindrical surface development surface (6), and the side wall plane development surface (5) and the filleted cylindrical surface development surface (6) are arranged in a spaced manner. The second curve (102) includes a second conical development surface (8) and a second back plane development surface (7), and the second conical development surface (8) and the second back plane development surface (7) are arranged in a spaced manner. The first curve (101) is externally movably provided with a round rolling die (9).

5. A collar shaper as claimed in claim 4, wherein: The connecting line of the side wall plane development surface (5) and the second back plane development surface (7) is a straight line, and the connecting line of the filleted cylindrical surface development surface (6) and the second conical development surface (8) is a parabola.

6. A collar shaper as claimed in claim 4, wherein: The round rolling die (9) includes an upper die (901) and a lower die (902), and the upper die (901) and the lower die (902) are both semihexagonal.

7. A one-piece collar shaper process for use in the collar shaper of any one of claims 1-6, characterized by, The method includes the following steps: S1, selecting a low-strength metal material plate with a thickness of 0.2-2mm capable of elastic-plastic deformation, cutting the plate to form a non-rectangular planar shape; S2, pre-bending the plate through a bending device and a bending knife, then performing a round rolling operation, controlling the forming of the barrel, and thus forming a collar former.

8. A collar shaper integrated forming process according to claim 7, wherein: The barrel is cylindrical, and S2 specifically includes the following steps: S211, bending along the connecting line of the cylindrical development surface (2) and the first conical development surface (3), that is, bending along the parabola, bending the planar plate to form a bending line, and separating the cylindrical development surface (2) and the first conical development surface (3) in the planar plate; S212, then only the cylindrical development surface (2) is subjected to the rounding process, and the rounding effect is achieved by multi-step segmented arc bending, or the upper and lower molds with semi-cylindrical surface characteristics are used to make the cylindrical development surface (2) pre-formed into a U-shaped bend by pressure instability, and then the U-shaped bend is further air-pressed to round into a cylinder. At the same time that the cylindrical development surface (2) is rounded, the first conical development surface (3) is bent into a conical surface, thereby forming a collar former of the cylindrical barrel; S213, according to the requirements, the cylindrical barrel collar former without a back plane can be obtained by further flattening operation to obtain a cylindrical barrel collar former containing a first back plane (4).

9. A collar shaper integral forming process according to claim 7, wherein: The barrel is non-cylindrical, and the S2 further includes the following steps: S221, the intersection line of the left and right sides of the flat panel is bent to form a bending line, and the intersection line of the rounded cylindrical surface development surface (6) and the side wall flat surface development surface (5) on the same side is also pre-bent, and then the intersection line of the second conical development surface (8) and the second back plane development surface (7) on the other side of the flat panel is pre-bent; S222, each rounded cylindrical surface development surface (6) is subjected to arc bending, and then the pre-bent first curved surface (101) is further air-pressed to round into a column in the upper mold (901) and the lower mold (902) with semi-rectangular characteristics, thereby forming a collar former of the rectangular barrel.

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