Sprue bushing and nozzle touch member

Abstract

To provide a sprue bushing and its nozzle touch member for preventing stringiness, which improves positioning ability and reproducibility of molding conditions. [Solution] The solution is a sprue bushing comprising: a sprue bushing body (2) having an expanded diameter portion (21) at one end of a cylindrical body (25) through which a sprue hole passes; a nozzle touch member (3) that can abut against the center; and fastening means (4) that connects the nozzle touch member to the sprue bushing body and fastens them to the mold, thereby fixing the nozzle touch member to the sprue bushing body; the resin introduction hole (32) has a cooling means to prevent stringiness; the expanded diameter portion of the sprue bushing body is provided with first engaging means; the nozzle touch member is provided with second engaging means; the first engaging means and the second engaging means engage to position the resin introduction hole so that the central axis of the resin introduction hole coincides with the central axis of the sprue hole; and the nozzle touch member is prevented from rotating circumferentially.

Description

[Technical Field]

[0001] This invention relates to a metal sprue bushing used when introducing molten resin from the nozzle of an injection molding machine into a mold, and its component parts, which include a nozzle touch part that abuts against the nozzle of the injection molding machine.In particular, it relates to a sprue bushing and its nozzle touch part that have a stringing prevention function. [Background technology]

[0002] Conventionally, a known sprue bushing with a stringing prevention function has a configuration in which, for example, a recess is formed in the end face on the nozzle touch side of a sprue bushing body having a sprue hole, a nozzle touch member is fitted into the recess, the nozzle touch member is provided with a nozzle touch surface and a through hole, and the through hole is provided with a partition wall for cooling purposes (see, for example, Patent Document 1). In the invention of Patent Document 1, the nozzle touch member can be replaced when it wears out.

[0003] Also known is a cartridge-type sprue bushing unit that includes a cartridge having a sprue hole for preventing stringiness, and that has a configuration in which the cartridge (nozzle touch member) is sandwiched between the sprue bushing body and the cartridge holder (see, for example, Patent Document 2). In the device according to Patent Document 2, the cartridge is also replaceable.

[0004] Also, a sprue bushing that prevents stringiness is known that has a configuration in which a plurality of ribs are provided radially for the purpose of cooling the molten resin (see, for example, Patent Document 3). FIG. 8 of Patent Document 3 shows a configuration in which a bush part (nozzle touch member) is placed on a sprue bush body, and a ring-shaped part is placed over it from above to clamp and fix the bush part. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-66563 [Patent Document 2] Registered Utility Model No. 3153374 [Patent Document 3] Patent No. 6049927 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, it is well known that in sprue bushings with an anti-stringing function, the nozzle touch member is replaceable, but the invention of Patent Document 1 involves fitting the nozzle touch member into a recess in the sprue bushing body, or fixing the nozzle touch member by lightly crimping part of its periphery with a punch or the like, which has the disadvantage that the nozzle touch member is easily fixed in an inaccurate manner. If the central axis of the nozzle touch member is misaligned with the central axis of the recess in the sprue bushing body or the sprue hole, problems will arise with the flow of the molten resin, which could result in short shots or poor reproducibility of molding conditions.

[0007] Furthermore, in configurations such as those in Patent Documents 2 and 3, in which a nozzle touch member is covered with a cartridge holder or a ring-shaped part and fixed with two screws, it is thought that the central axis of the nozzle touch member and the central axis of the sprue hole in the sprue bushing body usually coincide. However, in both Patent Documents 2 and 3, the nozzle touch member is not fixed in any way in the circumferential direction, and the circumferential position of the nozzle touch member changes each time it is cleaned or replaced. Therefore, if a cooling means such as a partition wall is provided in the resin introduction hole as in Patent Document 1, the position of the partition wall or the like will change, and it cannot be said that the reproducibility of molding conditions is sufficiently ensured.

[0008] The present invention was made in consideration of the above circumstances, and the problem that the invention aims to solve is to provide a sprue bushing and a nozzle touch member thereof that can increase the coaxiality between the central axis of the nozzle touch member and the central axis of the sprue hole and improve the reproducibility of molding conditions. [Means for solving the problem]

[0009] The above-mentioned problems are solved by a sprue bushing comprising: a sprue bushing body having an expanded diameter portion at one end of a cylindrical body through which a sprue hole passes; a nozzle touch member having a resin introduction hole in its center that is connected to the sprue hole and that can abut against the expanded diameter portion of the sprue bushing body; and fastening means that secures the nozzle touch member to the sprue bushing body by connecting the nozzle touch member to the sprue bushing body and fastening them to a mold, wherein the resin introduction hole has a cooling means for preventing stringiness. In this sprue bushing, the expanded diameter portion of the sprue bushing body is provided with first engaging means and the nozzle touch member is provided with second engaging means, and when the first engaging means and the second engaging means engage, the sprue bushing is positioned so that the central axis of the resin introduction hole coincides with the central axis of the sprue hole and is prevented from rotating circumferentially. [Effects of the Invention]

[0010] According to the present invention, a sprue bushing includes a sprue bushing body having an expanded diameter portion at one end of a cylindrical body through which a sprue hole passes, a nozzle touch member having a resin introduction hole in the center connected to the sprue hole and capable of contacting the expanded diameter portion of the sprue bushing body, and a fastening means for connecting the nozzle touch member to the sprue bushing body and fastening the nozzle touch member to the mold, and the resin introduction hole has a cooling means for preventing stringiness. In this sprue bushing, the expanded diameter portion of the sprue bushing body is provided with a first engaging means, and the nozzle touch member is fastened to the mold by connecting the nozzle touch member to the sprue bushing body. The nozzle touch member is provided with a second engaging means, and when the first engaging means and the second engaging means engage, the sprue bushing is positioned so that the central axis of the resin introduction hole and the central axis of the sprue hole are aligned, and circumferential rotation of the nozzle touch member is prevented.Therefore, positioning by the first engaging means and the second engaging means ensures that the cooling means for the resin introduction hole is always positioned in the same position and prevents circumferential deviation, thereby improving the reproducibility of molding conditions and increasing the coaxiality of the sprue bushing body and the nozzle touch member. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a sprue bushing according to an embodiment of the present invention. FIG. [Figure 2] 1 is a perspective view showing a state before assembly of a sprue bushing according to an embodiment of the present invention. FIG. [Figure 3] 1A is a plan view of a nozzle touch member of a sprue bushing according to an embodiment of the present invention; FIG. 1B is a cross-sectional view AA; and FIG. 1C is a cross-sectional view BB. [Figure 4] FIG. 10 is a perspective view showing a nozzle touch member used in a spray bushing according to another embodiment of the present invention, in which (a) the resin introduction hole is divided into two by a partition wall, (b) the resin introduction hole is divided into four by a partition wall, and (c) the nozzle touch member has a shape in which a notch is formed along the nozzle contact portion. DETAILED DESCRIPTION OF THE INVENTION

[0012] A sprue bushing according to one embodiment of the present invention comprises a sprue bushing body having an enlarged diameter portion at one end of a cylindrical body through which a sprue hole passes; a nozzle touch member having a resin introduction hole in its center that connects to the sprue hole and that can abut against the enlarged diameter portion of the sprue bushing body; and fastening means that connects the nozzle touch member to the sprue bushing body and fastens them to a mold, and the resin introduction hole has a cooling means for preventing stringiness. In this sprue bushing, the enlarged diameter portion of the sprue bushing body is provided with first engaging means, and the nozzle touch member is provided with second engaging means. When the first engaging means and the second engaging means engage, the sprue bushing is positioned so that the central axis of the resin introduction hole coincides with the central axis of the sprue hole, and circumferential rotation of the nozzle touch member is prevented (first configuration).

[0013] According to the first configuration, the cooling means for the resin introduction hole is always positioned in the same position by positioning using the first engaging means and the second engaging means, and circumferential deviation is prevented, thereby improving the reproducibility of molding conditions and increasing the coaxiality of the sprue bushing body and the nozzle touch member.

[0014] A sprue bushing according to another embodiment of the present invention has the above-described first configuration, and the first engagement means can be a convex portion protruding from one end side of the enlarged diameter portion of the sprue bushing body, and the second engagement means can be a notch formed by cutting out the side surface of the nozzle touch member (second configuration).

[0015] According to the second configuration, in addition to achieving the effects of the first configuration, the protrusion and the notch are engaged on the same plane, thereby reducing the bulk and enabling space saving.

[0016] A sprue bushing according to another embodiment has the second configuration described above, and the convex portions are arranged at the front and rear, the cutout portions are formed to include the front left and right and rear left and right of the nozzle touch member, and the nozzle touch member has corners having first and second surfaces at the front left and right and rear left and right positions, and the first and second surfaces of the corners abut against and engage with the convex portions (third configuration).

[0017] According to the third configuration, the convex portions are arranged at the front and rear, the cutout portions are formed to include the front left and right and rear left and right of the nozzle touch member, and are provided with corners having first and second surfaces at the front left and right and rear left and right positions of the nozzle touch member, and the first and second surfaces of the convex portions engage with the convex portions, thereby preventing the nozzle touch member from shifting in the front, back, left and right directions relative to the sprue bushing body and making it possible to enhance the reliability of the effect of the first configuration.

[0018] A sprue bushing according to another embodiment has the third configuration described above, and the convex portion of the sprue bushing body has a first side surface that abuts against a first surface of the corner of the nozzle touch member and a second side surface that abuts against a second surface of the corner, and a relief portion is provided at the intersection of the first surface and the second surface that constitute the corner (fourth configuration).

[0019] According to the fourth configuration, a relief portion is provided at the intersection of the first surface and the second surface that form the corner, thereby preventing the occurrence of an R surface during processing and ensuring reliable engagement with the convex portion.

[0020] Furthermore, the nozzle touch member used in any of the first to fourth configurations is an essential component for constructing the sprue bushing of the first to fourth configurations, and can improve the reproducibility of molding conditions and enhance coaxiality with the sprue bushing body. Furthermore, the nozzle touch member can be used alone as a consumable part.

[0021] The following describes a sprue bushing and its nozzle touch member according to an embodiment of the present invention. In the drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated. For ease of understanding, the drawings referred to below show simplified or schematic configurations, and some components are omitted. Furthermore, the dimensional ratios between components shown in each drawing do not necessarily represent actual dimensional ratios. [Example]

[0022] In describing the embodiments of the present invention, the "one end" of the sprue bushing 1 refers to the side that contacts the injection molding nozzle, and the "other end" refers to the opposite side, that is, the mold side.

[0023] As shown in FIGS. 1 and 2, a sprue bushing 1 according to an embodiment of the present invention includes a sprue bushing body 2, a nozzle touch member 3, and two fixing screws 4, 4.

[0024] 2, the sprue bushing body 2 has an expanded diameter portion 21 at one end of a cylindrical body 25 through which the sprue hole 20 passes. The diameter of the sprue hole 20 increases slightly from one end to the other end.

[0025] The enlarged diameter portion 21 of the sprue bushing body 2 is formed in a cylindrical or disc shape with a height less than its width, and has protrusions 23 protruding from an end face 22 toward one end. In this embodiment, the protrusions 23 are provided at two locations facing each other in a plan view. In other words, the protrusions 23 are provided at 180° intervals with respect to the center of the circle that constitutes the enlarged diameter portion 21 in a plan view.

[0026] Two body-side through holes 24 are provided in end face 22, facing each other in plan view. In other words, body-side through holes 24 are provided at 180° intervals based on the center of the circle that constitutes enlarged diameter portion 21 in plan view, and at positions that are 90° offset from the positions of the convex portions. Body-side through holes 24 are holes used to attach the sprue bushing to the mold, and are also holes for positioning and fixing sprue bushing body 2 and nozzle touch member 3.

[0027] The protrusion 23 has a generally semi-cylindrical outline in plan view and includes an upper surface 230 and four side surfaces. The four side surfaces are a side peripheral surface 231 that shares the outline of the expanded diameter portion, a first side surface 232 located opposite the side peripheral surface 231, and two second side surfaces 233, 233 that extend from the left and right ends of the first side surface 232 to the ends of the side peripheral surface 231. The first side surface 232 and the second side surface 233 are orthogonal in plan view, and a corner 234 formed by the first side surface 232 and the second side surface 233 is an engagement portion of the protrusion 23 with the nozzle touch member 3. In this embodiment, there are a total of four corners 234 for the two protrusions 23. Since the two protrusions are provided opposite each other as described above, the corners 234 are arranged such that the lines connecting the vertices of adjacent corners 234 form a rectangle in plan view.

[0028] 1 to 3, the nozzle touch member 3 has a circular plate shape with a notch 30A at the front and a notch 30B at the rear. At the top center, there is a nozzle abutment part 31 that curves downward toward the center and a resin introduction hole 32 that opens at the bottom center. On the left and right sides of the circular plate, there are counterbore-shaped screw attachment parts 34.

[0029] In this embodiment, a partition wall 33 is provided within the resin introduction hole 32, dividing the space of the introduction hole into three sections. The partition wall 33 is a cooling means that cools the molten resin to prevent stringiness. The central axis of the resin introduction hole 32 is aligned with the center of the sprue hole 20 of the sprue bushing body 2 when engaged with the sprue bushing body 2.

[0030] The front cutout 30A of the nozzle touch member 3 has a first restriction surface 300A that is continuous in the left-right width direction and two second restriction surfaces 301A that are formed in the front-rear direction. Similarly, the rear cutout 30B of the nozzle touch member 3 has a first restriction surface 300B that is continuous in the left-right width direction and two second restriction surfaces 301B that are formed in the front-rear direction. Corner portion 35A is formed by first surface 300A and second surface 301A of nozzle touch member 3. Similarly, corner portion 35B is formed by first surface 300B and second surface 301B of nozzle touch member 3. Furthermore, relief portions 302 are provided at each intersection of first surface 300A, 300B and second surface 301A, 301B to ensure good engagement with the sprue bushing body. More specifically, at each intersection of first surface 300A, 300B and second surface 301A, 301B, rounded surfaces are likely to be formed due to machining, and the formation of these rounded surfaces would hinder engagement with the sprue bushing body. However, by forming relief portions 302 and preventing the rounded surfaces, engagement with the sprue bushing body is ensured.

[0031] The screw mounting portion 34 of the nozzle touch member 3 has a through hole 340. The central axis of the through hole 340 coincides with the central axis of the body-side through hole 24 of the sprue bushing body 2 when engaged with the sprue bushing body 2.

[0032] The fixing screw, which is the fixing means, has a head on the base end side and a thread groove on the tip end side. The head is formed to be larger than the through hole 340 of the nozzle touch member 3 and smaller than the diameter of the counterbore.

[0033] Although not shown, the mold has a sprue bushing mounting hole for mounting the sprue bushing, and two screw holes around the sprue bushing mounting hole for threading with fixing screws 4, 4. These are well-known structures for mounting a conventional spray bushing, and the sprue bushing of the present invention can be used in a conventional mold as is.

[0034] The sprue bushing body 2, nozzle touch member 3, and fixing screw 4 having the above-described configuration can be fixed to the mold in the following procedure.

[0035] With the front side of the nozzle touch member 3 facing the front convex portion of the sprue bushing body 2, the nozzle touch member 3 is placed on the sprue bushing body 2 so that the central axes of the sprue hole 20 and body-side through-hole 24 in the sprue bushing body 2 are aligned with the central axes of the resin introduction hole 32 and through-hole 340 in the nozzle touch member 3. The nozzle touch member 3 fits between the front and rear convex portions 23, 23 of the sprue bushing body 2. In this state, the first and second side surfaces 232, 233 of the front convex portion 23 of the sprue bushing body 2 abut against the first and second restriction surfaces 300A, 301A of the nozzle touch member 3, and the first and second side surfaces 232, 233 of the rear convex portion 23 of the sprue bushing body 2 abut against the first and second restriction surfaces 300B, 301B of the nozzle touch member 3.

[0036] In this state, four corners 234 defined by the first side surface 232 and the second side surface 233 of the sprue bushing body 2 are engaged with the corners 35A and 35B. Therefore, due to the engagement of the corners 234 with the corners 35A and 35B, the central axis of the sprue hole 20 and the central axis of the resin introduction hole 32 are aligned, and the central axis of the body-side through hole 24 and the central axis of the through hole 340 in the nozzle touch member 3 are aligned. Furthermore, the orientation of each wall 33 is always determined to be the same. Furthermore, because the four corners 234 are engaged with the corners 35A and 35B, no circumferential misalignment occurs, ensuring sufficient reproducibility of molding conditions.

[0037] The cylindrical body 25 of the sprue bushing body 2 is inserted into the sprue bushing mounting hole of the mold (not shown), and the fixing screw 4 is threaded into the threaded hole of the mold, connecting the through hole 340 of the nozzle touch member 3 and the through hole 24 on the body side of the sprue bushing body 2.

[0038] Alternatively, only the sprue bushing body 2 may be inserted into the sprue bushing mounting hole of the mold first, and then the nozzle touch member 3 and the sprue bushing body 2 may be engaged.

[0039] As described above, the spray bushing 1 according to the embodiment of the present invention can improve the coaxiality of the sprue bushing body 2 and the nozzle touch member 3 with extremely simple operations, thereby ensuring sufficient reproducibility of molding conditions.

[0040] In the above embodiment, the partition walls 33 provided as cooling means for preventing stringing in the resin introduction hole 32 of the nozzle touch member 3 are configured so that three partition walls 33 join at the center of the resin introduction hole 32 to divide the space within the resin introduction hole 32 into thirds, but the present invention is not limited to this configuration, and for example, the space within the resin introduction hole 32 may be configured to be divided into two as shown in Figure 4(a) or into four as shown in Figure 4(b). The number of partition walls 33 can be selected by balancing the ease of passage of the fluid resin and the cooling efficiency for preventing stringing.

[0041] Furthermore, in the above embodiment, the nozzle touch member 3 is configured to have the first surfaces 300A, 300B across the entire width direction due to the cutout portions 30A, 30B, but the present invention is not limited to this configuration. For example, as shown in Figure 4(c), the first surfaces 300A, 300B can be formed only on both ends in the width direction, and the nozzle touch member 3 can have corner portions 35A, 35B together with the second surfaces 301A, 301B.

[0042] Furthermore, when using the nozzle touch member 3 of Figures 4(a) and (b), the orientation of the partition wall 33 remains unchanged even when rotated 180° in a plan view, which is advantageous in that the installation work can be performed without having to check the front and back of the nozzle touch member 3.

[0043] In contrast, when using the nozzle touch member 3 shown in the above embodiment, the orientation of the partition 33 changes when rotated 180° in a plan view, making it necessary to check the front and rear. However, the burden of checking can be reduced by, for example, providing an identification mark to distinguish between the front and rear.

[0044] The nozzle touch member 3 of the present invention can be removed or replaced by itself when it needs to be cleaned or when it becomes worn out, and this not only achieves the effects of the present invention described above but also makes it economical. [Explanation of symbols]

[0045] B Back D Downward F forward L left R Right side U upward 1 sprue bushing 2 Sprue bushing body 20 sprue holes 21 Expanded diameter part 22 End face 23 Convex part 230 Top 231 Side surface 232 First aspect 233 Second aspect 234 Corner 24 Body side through hole 25 Cylindrical body 3 Nozzle touch member 30A Notch 30B Notch 300A 1st side 300B 1st page 301A 2nd side 301B 2nd side 302 Relief 31 Nozzle contact part 32 Resin introduction hole 33 Bulkhead 34 Screw mounting part 340 through hole 35A Corner 35B Corner 4 Fixing screw (fixing means)

Claims

1. a sprue bushing body having a cylindrical body through which a sprue hole passes and an expanded diameter portion at one end; a nozzle touch member having a resin introduction hole in the center connected to the sprue hole and capable of contacting the expanded diameter portion of the sprue bushing body; and fastening means for connecting the nozzle touch member to the sprue bushing body and fastening the nozzle touch member to a mold, the fastening means being provided in the resin introduction hole to prevent stringiness; the enlarged diameter portion of the sprue bushing body is provided with a first engaging means, the nozzle touch member is provided with a second engagement means, When the first engaging means and the second engaging means are engaged, the sprue bushing is positioned so that the central axis of the resin introduction hole and the central axis of the sprue hole coincide with each other, and circumferential rotation of the nozzle touch member is prevented.

2. 2. The sprue bushing according to claim 1, wherein the first engaging means is a convex portion protruding from one end side of the enlarged diameter portion of the sprue bushing body, and the second engaging means is a notch formed by cutting out a side surface of the nozzle touch member.

3. 3. The sprue bushing according to claim 2, wherein the protrusions are disposed at the front and rear, the notches are formed to include the front left and right and rear left and right of the nozzle touch member, and the nozzle touch member is provided with corners having first and second surfaces at the front left and right and rear left and right positions, and the first and second surfaces of the corners abut against and engage with the protrusions.

4. the protrusion of the sprue bushing body has a first side surface that abuts against a first surface of a corner of the nozzle touch member and a second side surface that abuts against a second surface of the corner, 4. The sprue bushing according to claim 3, wherein a relief portion is provided at an intersection of said first surface and said second surface that constitute said corner portion.

5. A nozzle touch member constituting the sprue bushing according to any one of claims 1 to 4.

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