barrel

Abstract

The objective is to provide a barrel that is less prone to molding defects in the barrel body during resin molding. [Solution] The present invention relates to a barrel formed by resin molding, comprising a cylindrical barrel body and a flange extending radially from the base end of the barrel body, wherein the flange has at least one injection portion, which is the portion in the mold where resin is injected during resin molding, and a confluence portion, which is the portion in the mold forming the flange where the injected resin merges in opposing directions in the circumferential direction, and the cross section of the injection portion perpendicular to the circumferential direction of the injection portion is smaller than the cross section of the confluence portion perpendicular to the circumferential direction of the confluence portion.

Description

Technical Field

[0001] The present invention relates to a barrel used for a syringe.

Background Art

[0002] Conventionally, a barrel formed by resin molding such as injection molding has been known (Patent Document 1). The barrel formed by this resin molding has a cylindrical barrel body and a flange extending in the radial direction of the barrel body from the base end portion of the barrel body.

[0003] In this resin molding, the barrel is molded by filling a resin into a predetermined mold.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The above-mentioned resin molding mold has a shape in which the flow of the injected resin is considered at the part where the flange of the barrel is formed. Therefore, it is said that molding defects of the flange are unlikely to occur during the resin molding of the barrel, but molding defects may occur in the barrel body.

[0006] Therefore, an object of the present invention is to provide a barrel in which molding defects of the barrel body are unlikely to occur during resin molding.

Means for Solving the Problems

[0007] The inventors of this invention discovered that streaky marks sometimes appear on the barrel body of barrels formed by resin molding, and diligently conducted research to suppress the occurrence of these streaky marks. As a result, the inventors discovered that air and gas accumulate at the point where the resin injected into the mold converges during resin molding, and as the resin filling of the mold progresses, this rises (moves) along the barrel body, causing streaky marks to appear on the outer surface of the barrel body. The details are as follows.

[0008] In barrel resin molding, the barrel is formed by injecting resin from the gate (the part that forms the flange) and filling the mold with resin. However, by creating a molded product with a reduced amount of resin injected into the mold (short shot product: see Figure 17), the flow of resin within the mold was confirmed.

[0009] This confirmed that, in the mold, the flow of resin from the injection point in the flange-forming section to the barrel-forming section located near the injection point is delayed compared to the flow of resin from the injection point in the flange-forming section to the barrel-forming section located near the injection point. Specifically, the flow of resin from a point in the flange-forming section that is circumferentially further away from the injection point, or more precisely, from a confluence point where the resin flows in a direction opposite to the circumferential direction of the flange, to the barrel-forming section.

[0010] Furthermore, by investigating the flow of resin into the barrel body forming section, we found that air and gases generated from the resin accumulate in areas where the resin flow is delayed in the barrel body forming section. As the resin filling of the barrel body forming section progresses with these gases accumulated, the accumulated gases rise along the barrel body forming section, resulting in streaky marks as gas traces on the outer surface of the molded barrel body.

[0011] Therefore, the inventors focused on the above finding, namely, that when resin is injected into the part of the mold that forms the flange, the injected resin flows into the barrel body forming part located near the resin injection point before it has sufficiently flowed into the confluence point (the point where opposing directions in the circumferential direction converge) in the flange forming part, which tends to cause streaky marks on the outer surface of the molded barrel body, and created a barrel with the following configuration.

[0012] The barrel of the present invention is A barrel formed by resin molding, A cylindrical barrel body, The barrel body comprises a flange extending radially from the base end, The aforementioned flange is The injection section is the part in which the resin is injected into the mold during the aforementioned resin molding process, The portion of the mold forming the flange has at least one junction portion, which is a portion where the injected resins converge in opposing directions in the circumferential direction, In the flange, the injection section cross-section perpendicular to the circumferential direction of the injection section is smaller than the confluence section cross-section perpendicular to the circumferential direction of the confluence section.

[0013] In resin molding, molten resin injected into a narrow space tends to flow into a wider space. Therefore, with the barrel configuration described above, during resin molding, the resin injected into the mold portion forming the injection section easily flows into the mold portion forming the merging section. This reduces the difference in timing (i.e., the difference in the amount of resin flowing) between the mold portion forming the barrel body and the barrel body. As a result, streaky marks are less likely to appear on the outer surface of the barrel body during resin molding. In other words, molding defects in the barrel body are less likely to occur during resin molding.

[0014] In the aforementioned barrel, The injection section may have a constricted portion in the cross-section of the injection section, on the way from the position where the resin is injected into the mold to the barrel body in the radial direction inward.

[0015] With this configuration, during resin molding, the amount of resin flowing from the resin injection point to the part forming the barrel body radially inward in the mold is suppressed (see Figure 15). As a result, the delay in the flow of resin from the confluence part to the part forming the barrel body relative to the flow of resin to the part forming the barrel body near the resin injection point is effectively suppressed.

[0016] Furthermore, in the barrel, The injection portion has a first inner circumferential portion adjacent to the barrel body in the radial direction, In the flange, the thickness of the first inner circumference portion of the injection section may be less than the thickness of the confluence section.

[0017] With this configuration, during resin molding, the amount of resin flowing from the resin injection point towards the part where the barrel body is formed in the mold is suppressed. Therefore, the delay between the flow of resin into the barrel body formation part near the injection point and the flow of resin from the confluence point to the barrel body formation part is suppressed.

[0018] Furthermore, in the barrel, The flange has a second inner circumferential portion that extends from the first inner circumferential portion toward the confluence portion in the circumferential direction, The thickness of the second inner circumferential portion may be the same as the thickness of the first inner circumferential portion.

[0019] With this configuration, during resin molding, the amount of resin flowing towards the barrel body is suppressed in the mold from the resin injection point to the area forming the first inner circumferential portion and the area forming the second inner circumferential portion in the circumferential direction. As a result, the delay in the flow of resin from the area forming the confluence to the area forming the barrel body relative to the flow of resin to the barrel body near the injection point is suppressed.

[0020] Furthermore, in the barrel, The injection portion has a first outer peripheral portion outside the first inner peripheral portion in the radial direction, The flange has a second outer peripheral side portion extending from the first outer peripheral side portion toward the confluence portion side in the circumferential direction. The thickness of the second outer peripheral side portion may be greater than the thickness of the first inner peripheral side portion.

[0021] According to such a configuration, at the time of resin molding, in the mold, resin easily flows from the resin injection position through the portion forming the first outer peripheral portion and the portion forming the second outer peripheral portion to the portion where the confluence portion is formed. Therefore, the delay in the resin flowing from the portion forming the confluence portion to the portion forming the barrel body with respect to the resin flowing into the portion forming the barrel body near the injection portion can be suppressed.

[0022] Also, in the barrel, The injection portion has a first inner peripheral side portion adjacent to the barrel body in the radial direction. The confluence portion has a third inner peripheral side portion adjacent to the barrel body in the radial direction. The cross-section orthogonal to the circumferential direction of the first inner peripheral side portion may be smaller than the cross-section orthogonal to the circumferential direction of the third inner peripheral side portion.

[0023] According to such a configuration, at the time of resin molding, in the mold, resin easily flows from the portion forming the first inner peripheral side portion to the portion forming the third inner peripheral side portion. Therefore, the delay in the resin flowing from the portion forming the third inner peripheral side portion (confluence portion) to the portion forming the barrel body with respect to the resin flowing into the portion forming the barrel body near the injection portion through the first inner peripheral side portion from the injection position can be suppressed.

Advantages of the Invention

[0024] As described above, according to the present invention, it is possible to provide a barrel in which molding defects of the barrel body are unlikely to occur during resin molding.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 is a side view of the barrel of the present embodiment. [Figure 2A]Figure 2A is a view of the barrel from the base end. [Figure 2B] Figure 2B is a view of the barrel from the tip side. [Figure 3] Figure 3 is a cross-sectional view taken at position III-III in Figure 2A. [Figure 4] Figure 4 is a cross-sectional view of the IV-IV position in Figure 1. [Figure 5] Figure 5 is an unfolded view of the cross-section at the VV line position in Figure 2B. [Figure 6] Figure 6 is an unfolded view of the cross-section at the VI-VI line position in Figure 2B. [Figure 7] Figure 7 is a cross-sectional view of position VII-VII in Figure 4. [Figure 8] Figure 8 is a cross-sectional view of the VIII-VIII position in Figure 4. [Figure 9] Figure 9 is a cross-sectional view of the IX-IX position in Figure 4. [Figure 10] Figure 10 is a cross-sectional view of position XX in Figure 4. [Figure 11A] Figure 11A is a cross-sectional view taken at the point where the mold passes through the gate. [Figure 11B] Figure 11B is a cross-sectional view of the mold rotated 90° around the central axis of the barrel being formed, relative to Figure 11A. [Figure 12] Figure 12 is a diagram illustrating the flow of resin in the mold portion that forms the flange. [Figure 13] Figure 13 is a diagram illustrating the flow of resin in the mold portion that forms the outer circumference of the flange. [Figure 14] Figure 14 is a diagram illustrating the flow of resin in the mold portion that forms the inner circumference of the flange. [Figure 15] Figure 15 is a diagram illustrating the flow of resin in the mold portion that forms the injection section of the flange. [Figure 16] Figure 16 shows a short-shot version of the barrel. [Figure 17] Figure 17 shows a conventional barrel short-shot product. [Modes for carrying out the invention]

[0026] The following describes one embodiment of the present invention with reference to Figures 1 to 17.

[0027] The barrel in this embodiment is a barrel for a syringe used to administer drugs, and is integrally molded by resin molding such as injection molding. That is, the barrel is made of synthetic resin. This barrel is made of a material that has a predetermined transparency and can withstand the internal pressure applied when administering drug solution. The barrel in this embodiment is made of polypropylene (PP).

[0028] Specifically, as shown in Figures 1 to 4, the barrel 1 comprises a cylindrical barrel body 2 and a flange 3 extending radially from the base end of the barrel body 2.

[0029] The barrel body 2 is capable of containing a drug inside, and in this embodiment, the barrel body 2 contains, for example, a liquid drug. The barrel body 2 can also contain drugs other than liquid drugs, such as powdered drugs.

[0030] The barrel body 2 has a cylindrical body portion 21 extending in the direction of the central axis C, a cylindrical tip portion 22 smaller in diameter than the body portion 21 and positioned at one end of the body portion 21 in the direction of the central axis C (the upper end in Figures 1 and 3), and a shoulder portion 23 connecting the body portion 21 and the tip portion 22. The barrel body 2 of this embodiment also has a Luer lock portion 24 that extends from the shoulder portion 23 toward the tip in the direction of the central axis C, surrounding the tip portion 22 in the circumferential direction (around the central axis C). In the following, in the barrel 1, one end in the direction of the central axis C (the upper end in Figure 1) will be referred to as the tip, and the other end in the direction of the central axis C (the lower end in Figure 1) will be referred to as the base.

[0031] The body portion 21 is a cylindrical part capable of containing a drug, and has a first opening 210 at the base end (base end) 21a in the direction of the central axis C of the body portion 21, which serves as an inlet for the drug. In this embodiment, the outer diameter of the body portion 21 decreases towards the tip.

[0032] The tip portion 22 is the part that dispenses the drug contained in the body portion 21, and has a second opening 220 at its tip that serves as the drug outlet. In this embodiment, the outer diameter of the tip portion 22 decreases towards the tip.

[0033] The shoulder portion 23 is a plate-like part that extends radially inward from the tip of the torso portion 21 to the base of the tip portion 22. This shoulder portion 23 is annular when viewed from the direction of the central axis C.

[0034] The lure lock portion 24 is the part to which the cap, needle, etc., are connected. This lure lock portion 24 is a cylindrical part that extends from the shoulder portion 23 toward the tip in the direction of the central axis C and surrounds the tip portion 22 in the circumferential direction. This lure lock portion 24 has an internal thread on its inner circumferential surface.

[0035] The flange 3 is a plate-shaped portion that extends radially outward from the entire circumferential area of ​​the base end portion 21a of the body portion 21. In the flange 3 of this embodiment, the contour when viewed from the direction of the central axis C is circular (see Figures 2A and 2B). Specifically, the flange 3 has at least one injection portion 4, which is the portion where resin is injected into the mold 9 (see Figures 11A and 11B) when the barrel 1 is resin molded, at least one confluence portion 5, which is the portion where the resin merges within the mold 9 during the resin molding, and a plurality of intermediate portions 6, which are the portions between the injection portion 4 and the confluence portion 5 in the circumferential direction. In this flange 3, the injection portion cross-section D1 (see Figure 7) perpendicular to the circumferential direction of the injection portion 4 is smaller than the confluence portion cross-section D2 (see Figure 8) perpendicular to the circumferential direction of the confluence portion 5. In the flange 3 of this embodiment, the cross-sectional area of ​​the injection portion cross-section D1 is smaller than the cross-sectional area of ​​the confluence portion cross-section D2.

[0036] The flange 3 of this embodiment has multiple (two in the example shown in Figure 4) injection sections 4, multiple (two in the example shown in Figure 4) junction sections 5, and multiple (four in the example shown in Figure 4) intermediate sections 6. The two injection sections 4 are positioned radially opposite each other on the flange 3, and the two junction sections 5 are positioned radially opposite each other at a 90° circumferential angle to the injection sections 4. In the example shown in Figure 4, the injection sections 4 are located at both ends in the left-right direction on the flange 3, and the junction sections 5 are located at both ends in the up-down direction. The four intermediate sections 6 are each positioned between adjacent injection sections 4 and junction sections 5 in the circumferential direction.

[0037] As shown in Figures 4 to 7, the injection section 4 has an injection first portion (first inner circumferential portion) 41 adjacent to the barrel body 2 (specifically, the body portion 21). The injection section 4 also has an injection second portion (first outer circumferential portion) 42 located outside the injection first portion 41 in the radial direction. In this embodiment, the injection section 4 consists of the injection first portion 41 and the injection second portion 42 arranged radially (see Figure 7).

[0038] The first injection site 41 is the part of the flange 3 with the smallest thickness (the smallest dimension in the direction of the central axis C). In this embodiment, the first injection site 41 has a constant thickness in the circumferential direction (see Figure 5).

[0039] The second injection site 42 has a gate relief portion 421 that is recessed inward in the thickness direction (central axis C direction) (see Figures 6 and 7). A portion of the gate relief portion 421 (the radially inward end) may be included in the first injection site 41.

[0040] The gate relief portion 421 is a recessed area extending from the base end face 3b, which is the base end face of the flange 3, toward the tip end, and the outer end of the gate relief portion 421 in the radial direction is open (see Figure 7). This gate relief portion 421 is formed at the position of the gate 95 of the mold 9 when forming the barrel 1 (see Figure 11A). The base end face 3b of the flange 3 is a surface included in the end face 1b on the base end side in the direction of the central axis C of the barrel 1, and the end face 1b of the barrel 1 is a plane that extends in a plane direction perpendicular to the central axis C (see Figures 1 and 2A).

[0041] In the injection section 4 of this embodiment, a gate relief section 421 is formed, and in the cross-section D1 of the injection section, a constricted section 43 is formed on the way from the position where the resin is injected into the mold 9 (the position corresponding to the gate 95) to the barrel body 2 radially inward (see Figure 7).

[0042] This constricted portion 43 is a portion in the injection section cross-section D1 that is narrower than the radially adjacent portion. Therefore, during resin molding of the barrel 1, resin has difficulty flowing radially inward from the gate 95 (i.e., toward the portion forming the barrel body 2) in the portion of the mold 9 where the constricted portion 43 is formed (see arrow A2 in Figure 15).

[0043] As shown in Figures 4 to 6 and 8, the confluence section 5 has a first confluence portion (third inner circumference portion) 51 adjacent to the barrel body 2. The confluence section 5 also has a second confluence portion 52 outside the first confluence portion 51 in the radial direction. In this embodiment, the confluence section 5 consists of a first confluence portion 51 and a second confluence portion 52 arranged radially (see Figure 8).

[0044] The thickness of the first confluence portion 51 is greater than the thickness of the first injection portion 41. In this embodiment, the thickness of the first confluence portion 51 is the same at each position in the circumferential direction (see Figure 5).

[0045] The second confluence section 52 is the thickest part of the flange 3. That is, the thickness of the second confluence section 52 is greater than the thickness of the first confluence section 51 (see Figure 8).

[0046] The intermediate section 6 has an injection-side portion 6A adjacent to the injection section 4 in the circumferential direction, and a confluence-side portion 6B adjacent to the confluence section 5 in the circumferential direction (see Figure 4). In this embodiment, the intermediate section 6 consists of an injection-side portion 6A and a confluence-side portion 6B arranged in the circumferential direction.

[0047] As shown in Figures 4-6 and 9, the injection-side portion 6A has an intermediate first portion (second inner circumference portion) 61 adjacent to the barrel body 2. The injection-side portion 6A also has an intermediate second portion (second outer circumference portion) 62 outside the intermediate first portion 61 in the radial direction. In this embodiment, the injection-side portion 6A consists of the intermediate first portion 61 and the intermediate second portion 62 aligned in the radial direction (see Figure 9).

[0048] The intermediate first portion 61 is the portion that extends from the injection first portion 41 toward the circumferential confluence portion 5. The thickness of this intermediate first portion 61 is the same at each position in the circumferential direction (see Figure 5). In this embodiment, the thickness of the intermediate first portion 61 is the same as the thickness of the injection first portion 41.

[0049] The intermediate second section 62 is the portion that extends from the injection second section 42 toward the circumferential confluence section 5. This intermediate second section 62 is the thickest part of the flange 3. That is, the thickness of the intermediate second section 62 is greater than the thickness of the intermediate first section 61. Also, the thickness of the intermediate second section 62 is the same as the thickness of the confluence second section 52 (see Figures 8 and 9).

[0050] As shown in Figures 4-6 and 10, the confluence side portion 6B has an intermediate third portion 63 adjacent to the barrel body 2. Furthermore, the confluence side portion 6B has an intermediate fourth portion 64 located outside the intermediate third portion 63 in the radial direction. In this embodiment, the confluence side portion 6B consists of the intermediate third portion 63 and the intermediate fourth portion 64 aligned radially (see Figure 10).

[0051] The intermediate third section 63 is a section that extends circumferentially from the intermediate first section 61 to the confluence first section 51. The thickness of this intermediate third section 63 increases as it moves from the first boundary position P1 with the intermediate first section 61 toward the confluence first section 51 (see Figure 5). That is, the thickness of the intermediate third section 63 gradually increases as it moves toward the confluence first section 51 in the circumferential direction. Specifically, the thickness of the intermediate third section 63 is the same as the thickness of the intermediate first section 61 at the first boundary position P1 with the intermediate first section 61, and becomes the same as the thickness of the confluence first section 51 at the second boundary position P2 with the confluence first section 51, thus increasing as it moves from the first boundary position P1 toward the second boundary position P2. As a result, the tip side surface 63a of the intermediate third section 63 is inclined with respect to the tip side surface 61a of the intermediate first section 61.

[0052] The intermediate fourth section 64 is a section that extends circumferentially from the intermediate second section 62 to the confluence second section 52. This intermediate fourth section 64 is the thickest section of the flange 3. That is, the thickness of the intermediate fourth section 64 is greater than the thickness of the intermediate third section 63 at each circumferential position. Also, the thickness of the intermediate fourth section 64 is the same as the thickness of the confluence second section 52 (see Figures 8 and 10).

[0053] In the flange 3 of this embodiment, the outer periphery 32 of the flange 3 is formed by the sequential arrangement of the injection second portion 42, intermediate second portion 62, intermediate fourth portion 64, confluence second portion 52, intermediate fourth portion 64, intermediate second portion 62, injection second portion 42, intermediate second portion 62, intermediate fourth portion 64, confluence second portion 52, intermediate fourth portion 64, and intermediate second portion 62 in the circumferential direction (see Figure 4).

[0054] In this outer peripheral portion 32, the thickness is the same at each position in the circumferential direction, excluding the gate relief portion 421 (injection portion 4) (see Figure 6).

[0055] Furthermore, in the flange 3, the injection first section 41, intermediate first section 61, intermediate third section 63, confluence first section 51, intermediate third section 63, intermediate first section 61, injection first section 41, intermediate first section 61, intermediate third section 63, confluence first section 51, intermediate third section 63, and intermediate first section 61 are arranged in sequence in the circumferential direction to constitute the inner circumference 31 of the flange 3.

[0056] In this inner circumference 31, the tip side surface 41a of the injection first section 41 and the tip side surface 61a of the intermediate first section 61 form a single plane without any steps, and this plane extends in a direction perpendicular to the central axis C. Furthermore, the tip side surface 51a of the confluence first section 51 is a plane that extends in a direction perpendicular to the central axis C at a position displaced toward the tip side in the direction of the central axis C relative to the plane formed by the tip side surface 41a of the injection first section 41 and the tip side surface 61a of the intermediate first section 61. Furthermore, the tip side surface 63a of the intermediate third section 63 is a plane that is inclined with respect to the plane formed by the tip side surface 41a of the injection first section 41 and the tip side surface 61a of the intermediate first section 61, and is also inclined with respect to the tip side surface 51a of the confluence first section 51 (see Figure 5).

[0057] The manufacturing method of barrel 1 will be described below. First, the mold 9 used for resin molding of barrel 1 (injection molding in this embodiment) will be described with reference to Figures 11A and 11B, and then the manufacturing method of barrel 1 will be described in detail.

[0058] The mold 9 comprises a core 91 and cavities 92 and 93. The space S formed between the core 91 and cavities 92 and 93 in the mold 9 after clamping is the same shape (outer shape) as the barrel 1. That is, the barrel 1 is formed by filling the space S of the mold 9 after clamping with molten resin (PP in this embodiment). The mold 9 only needs to be able to form the barrel 1, and its specific configuration (number of parts, etc.) is not limited.

[0059] The cavity 92 has a gate 95 that can supply resin into the space S of the mold 9. This gate 95 is positioned in the cavity 92 at a location where the gate relief portion 421 of the barrel 1 is formed, and is connected to an injection molding machine. Specifically, the gate 95 is positioned in the cavity 92 at a location where the gate relief portion 421 of the barrel 1 is formed, and is configured to inject (inject) resin into the space S toward the tip side of the barrel 1 (see Figure 11A). The mold 9 of this embodiment has two gates 95.

[0060] Next, we will explain the manufacturing method of barrel 1.

[0061] In the clamped mold 9, resin (molten resin) is injected into the space S from each gate 95.

[0062] The resin injected into the space S from the gate 95 flows in the mold 9 from the area forming the second injection area 42 to the areas adjacent to it in the circumferential direction (the areas forming the intermediate second area 62) (see arrow A1 in Figures 12 and 13), and also flows into the first injection area 41 (see arrow A2 in Figures 12 and 15). At this time, the resin flowing into the first injection area 41 has difficulty flowing (high resistance) because it passes through the constricted area 43, and as a result, much of the resin injected into the area forming the second injection area 42 flows into the area forming the intermediate second area 62.

[0063] In the mold 9, most of the resin that flows into the area forming the intermediate second section 62 flows through the area forming the intermediate fourth section 64, which has a large flow channel cross-sectional area, and then flows into the area forming the confluence second section 52 (see arrows A3 and A4 in Figures 12 and 13).

[0064] At this time, in the mold 9, some of the resin flowing through the section forming the intermediate second section 62 and the section forming the intermediate fourth section 64 also flows into the section forming the intermediate first section 61 and the section forming the intermediate third section 63, which have smaller flow channel cross-sectional areas (see arrows A5 and A6 in Figure 12).

[0065] Meanwhile, in the mold 9, the resin that flows into the area forming the first injection area 41 flows into the area forming the barrel body 2 (more specifically, the body portion 21) (hereinafter referred to as the "barrel body forming area"), as well as into the areas adjacent to it in the circumferential direction (the areas forming the intermediate first area 61) (see arrows A7 and A8 in Figures 12 and 14).

[0066] Furthermore, in the mold 9, the resin that flows into the area forming the intermediate first section 61 flows into the barrel body forming section and also flows into the area forming the intermediate third section 63 (see arrows A9 and A10 in Figures 12 and 14).

[0067] Furthermore, in the mold 9, the resin that flows into the area forming the intermediate third section 63 flows into the barrel body forming section and also flows into the area forming the confluence first section 51 (see arrows A11 and A12 in Figures 12 and 14). At this time, in the mold 9, in the area forming the intermediate third section 63, the spacing in the thickness direction increases as it moves towards the area forming the confluence first section 51 (i.e., the flow path cross-sectional area increases: see Figure 14), so the flow rate of resin heading towards the area forming the confluence first section 51 is greater than the flow rate of resin heading towards the barrel body forming section.

[0068] Next, in the mold 9, at the part that forms the second merging section 52, the resin that has flowed in from the adjacent parts in the circumferential direction (the parts that form the intermediate fourth section 64) merges in opposing directions in the circumferential direction and flows into the part that forms the first merging section 51 (see arrows A13 and A14 in Figure 12).

[0069] Furthermore, in the mold 9, at the part that forms the first merging part 51, the resin that has flowed in from the adjacent parts in the circumferential direction (the parts that form the intermediate third part 63) merges in opposing directions in the circumferential direction, while the resin that has flowed in from the part that forms the second merging part 52 also merges (see arrows A14 and A15 in Figure 12).

[0070] Then, in the mold 9, the resin that merges at the part forming the first merging section 51 flows into the barrel body forming section (see arrow A16 in Figure 12).

[0071] In this way, in the mold 9, the filling of the barrel body forming section progresses as resin flows in from the parts forming each section 41, 42, 51, 52, and 61-64 of the flange 3.

[0072] In this embodiment, the mold 9 makes the thickness-direction spacing (the spacing of the walls defining the space S) of the parts forming the inner circumference 31 of the flange 3 larger in the part forming the first confluence part 51 than in the part forming the first injection part 41. As a result, more resin injected into the part forming the injection part 4 flows into the part forming the confluence part 5 than from the barrel body forming part near the part forming the injection part 4. Therefore, the difference between the amount of resin flowing from the injection part 4 to the barrel body forming part and the amount of resin flowing from the confluence part 5 to the barrel body forming part is suppressed.

[0073] As a result, as the resin filling progresses into the barrel body forming section, the difference β1 in the direction of the central axis C between the position P11 of the edge of the resin filling in the area corresponding to the circumferential injection section 4 (the area indicated by the dot in Figure 16) and the position P12 of the edge of the resin filling in the area corresponding to the circumferential confluence section 5 is suppressed, as shown in Figure 16. Consequently, as the resin filling progresses in the barrel body forming section of the mold 9, the angle α1 of the V-shaped edge of the resin formed at the position corresponding to the circumferential confluence section 5 becomes larger than the angle α2 of the V-shaped edge of the resin formed at the position corresponding to the circumferential confluence section (see Figure 17) when the thickness of the flange of the resin-molded barrel is constant at each position in the circumferential direction, as the resin filling progresses in the barrel body forming section of the mold (the area indicated by the dot in Figure 17). As a result, when the resin filling progresses in the barrel body forming section of mold 9, gas and other substances are less likely to accumulate at the bent position of the V-shaped edge of the resin, or gas and other substances are less likely to be trapped in the resin as the filling progresses and more likely to escape towards the tip. The dotted areas in Figures 16 and 17 show so-called short shot products, which were molded with a reduced amount of resin injected into the mold in order to check the flow of resin inside the mold.

[0074] Once the space S of the mold 9 is filled with resin, the injection (filling) of resin from each gate 95 is stopped. Subsequently, the temperature of the resin inside the mold 9 is lowered by cooling or other means to allow it to harden, and then the cavities 92 and 93 are moved to open the mold 9. This results in the barrel 1 being produced.

[0075] The barrel 1 described above is a barrel 1 formed by resin molding, comprising a cylindrical barrel body 2 and a flange 3 extending radially from the base end 21a of the barrel body 2. The flange 3 has at least one injection portion 4, which is the part in the mold 9 where resin is injected during resin molding, and at least one confluence portion 5, which is the part in the mold 9 that forms the flange 3 where the injected resin merges in opposing directions in the circumferential direction. In the flange 3, the injection portion cross-section D1 (see Figure 7) perpendicular to the circumferential direction of the injection portion 4 is smaller than the confluence portion cross-section D2 (see Figure 8) perpendicular to the circumferential direction of the confluence portion 5.

[0076] In resin molding, resin (molten resin) injected into a narrow space tends to flow into a wider space. Therefore, with the barrel 1 configured as described above, during resin molding, the resin injected into the part of the mold 9 that forms the injection section 4 tends to flow into the part of the mold 9 that forms the confluence section 5. This reduces the difference in timing (i.e., the difference in the amount of resin that flows in) of the resin flowing into the part of the mold 9 that forms the barrel body 2. As a result, streaky marks are less likely to appear on the outer surface of the barrel body 2 during resin molding. In other words, molding defects in the barrel body 2 are less likely to occur during resin molding.

[0077] Furthermore, in the barrel 1 of this embodiment, the injection section 4 has a constricted portion 43 in the injection section cross-section D1 (see Figure 7) on the way from the position (gate) 95 where the resin is injected into the mold 9 to the barrel body 2 radially inward. Therefore, when resin molding the barrel 1, the amount of resin flowing from the resin injection position (gate) 95 to the part that forms the barrel body 2 radially inward in the mold 9 is suppressed (see Figure 15). As a result, in the mold 9, the delay in the flow of resin from the part that forms the confluence 5 to the part that forms the barrel body 2 relative to the flow of resin to the part that forms the barrel body 2 near the injection section 4 is effectively suppressed.

[0078] Furthermore, in the barrel 1 of this embodiment, the injection section 4 has a first injection section (first inner circumference section) 41 adjacent to the barrel body 2 in the radial direction, and in the flange 3, the thickness of the first injection section 41 is smaller than the thickness of the confluence section 5 (see Figures 7 and 8). Therefore, during resin molding, the amount of resin flowing from the resin injection position (gate) 95 toward the section where the barrel body 2 is formed in the mold 9 is suppressed. As a result, in the mold 9, the delay in the flow of resin from the section forming the confluence section 5 toward the section forming the barrel body 2 relative to the flow of resin into the section forming the barrel body 2 near the injection section 4 is suppressed.

[0079] Furthermore, in the barrel 1 of this embodiment, the flange 3 has an intermediate first portion (second inner circumferential portion) 61 that extends from the injection first portion (first inner circumferential portion) 41 toward the circumferential confluence portion 5, and the thickness of the intermediate first portion 61 is the same as the thickness of the injection first portion 41 (see Figure 5). Therefore, during resin molding, in the mold 9, the amount of resin flowing toward the portion where the barrel body 2 is formed is suppressed in the range from the resin injection position (gate) 95 to the portion where the injection first portion 41 is formed and the portion where the intermediate first portion 61 is formed in the circumferential direction. As a result, in the mold 9, the delay in the flow of resin from the portion where the confluence portion 5 is formed toward the portion where the barrel body 2 is formed toward the portion where the barrel body 2 is formed toward the portion near the injection portion 4 is suppressed.

[0080] Furthermore, in the barrel 1 of this embodiment, the injection section 4 has a second injection section (first outer circumference section) 42 outside the first injection section (first inner circumference section) 41 in the radial direction, and the flange 3 has an intermediate second section (second outer circumference section) 62 extending from the second injection section 42 toward the confluence section 5 in the circumferential direction, and the thickness of the intermediate second section 62 is greater than the thickness of the first injection section 41 (see Figures 7 and 9). Therefore, during resin molding, resin flows easily from the resin injection position (gate) 95 in the mold 9 through the sections forming the second injection section 42 and the intermediate second section 62 to the section where the confluence section 5 is formed. As a result, in the mold 9, the delay in the flow of resin from the section forming the confluence section 5 to the section forming the barrel body 2 relative to the flow of resin to the section forming the barrel body 2 near the injection section 4 is suppressed.

[0081] Furthermore, in the barrel 1 of this embodiment, the injection section 4 has an injection first section (first inner circumferential section) 41 adjacent to the barrel body 2 in the radial direction, and the confluence section 5 has a confluence first section (third inner circumferential section) 51 adjacent to the barrel body 2 in the radial direction, and the cross section of the injection first section 41 perpendicular to the circumferential direction is smaller than the cross section of the confluence first section perpendicular to the circumferential direction (see Figures 7 and 8). Therefore, during resin molding, resin flows more easily from the section forming the injection first section 41 to the section forming the confluence first section 51 in the mold 9, thus suppressing the delay between the flow of resin from the section forming the confluence first section 51 (confluence section 5) to the section forming the barrel body 2, relative to the flow of resin from the injection position (gate) 95 through the injection first section 41 to the section forming the barrel body 2 near the injection section 4.

[0082] It should be noted that the barrel of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of one embodiment can be deleted.

[0083] Although the barrel 1 in the above embodiment is made of polypropylene, it may be made of other synthetic resins.

[0084] Furthermore, the barrel 1 in the above embodiment adjusts the flow of resin within the mold 9 during resin molding by changing the thickness of the flange 3 (in the example of the above embodiment, the thickness of the inner circumference 31), thereby suppressing the difference in the timing of resin flow into the part forming the barrel body 2 from each position in the circumferential direction (difference in the amount of resin flowing in), but the configuration is not limited to this. The flow of resin within the mold 9 during resin molding may be adjusted by changing the radial dimensions of the flange 3, or by changing both the radial dimensions and the thickness. In other words, the shape of the flange 3 (in other words, the shape of the part forming the flange 3) should be adjusted in the mold 9 so as to adjust the ease of resin flow in the part forming the flange 3, thereby suppressing the difference in the amount of resin flowing in at each position in the circumferential direction in the part forming the barrel body 2.

[0085] Furthermore, in the barrel 1 of the above embodiment, the thickness of the flange 3 is changed by displacing the surface of the flange 3 facing the tip side in the direction of the central axis C, but the configuration is not limited to this. The thickness of the flange 3 may be changed by displacing the surface of the flange 3 facing the base side in the direction of the central axis C, or the thickness of the flange 3 may be changed by displacing both the surface facing the tip side and the surface facing the base side of the flange 3 in the direction of the central axis C.

[0086] Furthermore, although the flange 3 in the above embodiment has a gate relief portion 421 at the base end of the flange 3, the configuration is not limited to this. The gate relief portion 421 may be located at the tip end of the flange 3, or the flange 3 may not have a gate relief portion 421. If the flange 3 does not have a gate relief portion 421, the constricted portion 43 will not be formed in the injection portion cross-section D1.

[0087] Furthermore, in the flange 3 of the above embodiment, the outer circumference 32 has a different shape from the inner circumference 31, but the configuration is not limited to this. The outer circumference 32 may have the same shape as the inner circumference 31.

[0088] Furthermore, in the flange 3 of the above embodiment, the tip side surface 41a of the injection first portion 41, the tip side surface 61a of the intermediate first portion 61, and the tip side surface 51a of the confluence first portion 51 are all planes perpendicular to the central axis C, but the configuration is not limited to this. Each of the tip side surfaces 41a, 51a, and 61a may be a surface inclined with respect to the central axis C, or it may be a surface other than a plane, such as a curved surface or an uneven surface.

[0089] Furthermore, in the flange 3 of the above embodiment, the tip side surface 63a of the intermediate third portion 63 is a plane that slopes from the first boundary position P1 to the second boundary position P2, but the configuration is not limited to this. The tip side surface 63a of the intermediate third portion 63 may be a surface other than a plane, such as a curved surface, a gently undulating surface, or an uneven surface.

[0090] Furthermore, in the mold 9 that forms the barrel 1 of the above embodiment, the gate 95 injects (injects) resin toward the tip side at the part that forms the gate relief portion 421, but the mold 9 is not limited to this configuration. In the mold 9, the gate 95 may be configured to inject resin radially inward or circumferentially at the part that forms the gate relief portion 421. Also, in the mold 9, the gate 95 may be configured to inject resin toward the base end at the part that forms the injection portion 4 of the flange 3.

[0091] Furthermore, the specific shape of barrel 1 is not limited. As long as the body portion 21 of barrel body 2 is cylindrical, the shapes of the tip portion 22 and the luer lock portion 24 can be selected in various ways. Also, barrel body 2 may be configured without the luer lock portion 24. In addition, the cross-sectional shape of the body portion 21 does not have to be circular. [Explanation of symbols]

[0092] 1...Barrel, 1b...End face at the base, 2...Barrel body, 21...Body, 21a...Base end, 210...First opening, 22...Tip, 220...Second opening, 23...Shoulder, 24...Luer lock section, 3...Flange, 3b...Base end face, 31...Inner circumference, 32...Outer circumference, 4...Injection section, 41...First injection area, 41a...Side of tip, 42...Second injection area, 421...Gate relief section, 43...Constricted section, 5...Confluence section, 51...First confluence area, 51a...Side of tip, 52...Second confluence area, 6...Middle section 6A...Injection side section, 6B...Confluence side section, 61...First intermediate section, 61a...Tip side, 62...Second intermediate section, 63...Third intermediate section, 63a...Tip side, 64...Fourth intermediate section, 9...Mold, 91...Core, 92, 93...Cavity, 95...Gate, C...Central axis, D1...Injection section cross-section, D2...Confluence section cross-section, P1...First boundary position, P2...Second boundary position, P11, P12...Position of resin edge, S...Mold space, α1, α2...Angle of resin edge, β1...Difference in resin edge position

Claims

1. A barrel formed by resin molding, A cylindrical barrel body, The barrel body comprises a flange extending radially from the base end, The aforementioned flange is The injection section is the part in which the resin is injected into the mold during the aforementioned resin molding process, The portion of the mold forming the flange has at least one junction portion, which is a portion where the injected resins converge in opposing directions in the circumferential direction, In the flange, the cross-section of the injection portion perpendicular to the circumferential direction of the injection portion is smaller than the cross-section of the confluence portion perpendicular to the circumferential direction of the confluence portion, forming a barrel.

2. The barrel according to claim 1, wherein the injection portion has a constricted portion in the cross-section of the injection portion, on the way from the position where the resin is injected into the mold to the barrel body radially inward.

3. The injection portion has a first inner circumferential portion adjacent to the barrel body in the radial direction, The barrel according to claim 1 or 2, wherein the thickness of the first inner circumferential portion of the injection section in the flange is smaller than the thickness of the confluence section.

4. The flange has a second inner circumferential portion that extends from the first inner circumferential portion toward the confluence portion in the circumferential direction, The barrel according to claim 3, wherein the thickness of the second inner circumference portion is the same as the thickness of the first inner circumference portion.

5. The injection portion has a first outer peripheral portion outside the first inner peripheral portion in the radial direction, The flange has a second outer peripheral portion that extends from the first outer peripheral portion toward the merging portion in the circumferential direction, The barrel according to claim 3, wherein the thickness of the second outer circumference portion is greater than the thickness of the first inner circumference portion.

6. The injection portion has a first inner circumferential portion adjacent to the barrel body in the radial direction, The confluence portion has a third inner circumferential portion adjacent to the barrel body in the radial direction, The barrel according to claim 1 or 2, wherein the cross-section of the first inner circumferential portion perpendicular to the circumferential direction is smaller than the cross-section of the third inner circumferential portion perpendicular to the circumferential direction.

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