Mold structure

Abstract

To provide a mold structure capable of easily performing burr removal and sprue runner removal operations in a short time and at low cost by using the mold alone without any additional operations, by performing these two removal operations simultaneously with a mold opening operation.SOLUTION: A mold structure 1 includes: a product nest unit 6 that is provided inside the mold structure having a pair of molds 4 and 5 that can be moved toward or away from each other, and forms a cavity 2 for molding a predetermined product; a support nest unit 7 that movably supports the product nest unit and forms a sprue runner 3 for pouring molten resin into the cavity; and positioning and moving means 8 that moves the product nest unit and the support nest unit in opposite directions at the same time and positions them at a preset position when the pair of molds are separated from each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a mold structure. [Background technology]

[0002] For example, a two-plate type mold structure having a fixed mold and a movable mold is known. The fixed mold is fixed at a preset position. The movable mold is detachably joined to the fixed mold. The fixed mold and the movable mold each have a parting line (PL) surface (i.e., a fixed-side PL surface and a movable-side PL surface).

[0003] In this case, a cavity and a sprue runner are constructed inside the mold structure by joining the movable mold to the fixed mold (i.e., closing the mold) so that the PL surfaces are in contact with each other. At this time, molten resin is poured from the sprue runner into the cavity, molding a product that follows the contours of the cavity. The molded product (hereinafter referred to as the molded product) is then removed from inside the mold structure by separating the movable mold from the fixed mold (i.e., opening the mold) so that the PL surfaces are separated from each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6643147 [Patent Document 2] Patent No. 6590649 [Patent Document 3] Patent No. 3413435 [Patent Document 4] Utility Model Registration No. 2581790 Summary of the Invention [Problem to be solved by the invention]

[0005] However, depending on the level of holding pressure used to prevent the backflow of molten resin poured into the cavity and the clamping force applied to both molds when closing them, molten resin may leak into the gaps between the PL surfaces or into the gas vents on the PL surfaces, causing flash on the molded product. In such cases, it is necessary to quickly remove the flash from the molded product.

[0006] Furthermore, the sprue runner is merely a component that serves as a passage for the molten resin to flow into the cavity, and therefore, after molding, it is required to quickly remove the sprue runner from the inside of the mold structure.

[0007] However, to remove burrs from molded products, the burr removal work must be performed individually for each molded product. Furthermore, the removal of sprue runners from inside the mold structure (i.e., gate cutting) can be automated using auxiliary equipment such as a take-out machine. However, this requires the introduction of auxiliary equipment and the teaching of an operating program for each mold, which is not only time-consuming, but also makes it impossible to perform the removal process using the mold alone. This results in a lot of effort, time, and cost required for the burr removal work and sprue runner removal work.

[0008] In addition, in recent years, with the trend toward high-mix, low-volume production in Japan's resin molding processes, the deburring and gate cutting described above are often done manually, which means that space and time must be allocated separately for each removal step, which is costly and troublesome.

[0009] The object of the present invention is to provide a mold structure that enables the burr removal and sprue runner removal operations to be performed simultaneously with the mold opening operation, thereby enabling these two removal operations to be performed easily in a short time at low cost using the mold alone without any additional work. [Means for solving the problem]

[0010] According to an embodiment, the mold structure includes a product nesting unit that is provided inside the mold structure having a pair of molds that can be moved toward or away from each other and that forms a cavity for molding a predetermined product, a support nesting unit that movably supports the product nesting unit and forms a sprue runner for pouring molten resin into the cavity, and a positioning and moving means that simultaneously moves the product nesting unit and the support nesting unit in opposite directions and positions them at a predetermined position when the pair of molds are separated from each other. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a mold structure in a closed state in one embodiment, in which the upper half is a diagram illustrating the layout configuration inside the mold structure, and the lower half is a diagram illustrating the layout configuration inside the mold structure, focusing on the cavity and sprue runner. [Figure 2] FIG. 1 is a cross-sectional view of a mold structure in an open state in one embodiment, in which the upper half is a diagram illustrating the layout and configuration of the interior of the mold structure, and the lower half is a diagram illustrating the layout and configuration of the interior of the mold structure, focusing on the cavity and sprue runner. [Figure 3] FIG. 10 is a cross-sectional view of a mold structure in an open state in a modified example, in which the upper half is a diagram of the layout configuration inside the mold structure, and the lower half is a diagram of the layout configuration inside the mold structure focusing on the cavity and sprue runner. DETAILED DESCRIPTION OF THE INVENTION

[0012] "One embodiment" FIG. 1 is a diagram showing the internal configuration of a mold structure 1 according to this embodiment, and the lower half of the figure also shows the internal configuration, focusing on a cavity 2 and a sprue runner 3. The cavity 2 and sprue runner 3 are constructed inside the mold structure 1, which will be described later. The cavity 2 refers to a space (gap) for molding a predetermined product. The sprue runner 3 refers to a passage (path) for pouring molten resin into the cavity 2.

[0013] FIG. 1 shows, as an example, a two-plate type mold structure 1 having a pair of molds (i.e., a fixed mold 4 and a movable mold 5). The mold structure 1 is installed on a platen (not shown), whereby the pair of molds (fixed mold 4, movable mold 5) are set so that they can be moved toward or away from each other. At this time, the fixed mold 4 is fixed at a preset position. The movable mold 5 is disposed opposite the fixed mold 4 so that they can be moved toward or away from each other (separated and joined).

[0014] Here, the separation direction (i.e., separation direction D1, joining direction D2) that relatively separates and contacts this pair of molds (fixed mold 4, movable mold 5) can be defined, for example, as a direction perpendicular to the parting line (PL) surfaces 4s, 5s described below.

[0015] 1, parting line (PL) surfaces (i.e., a fixed-side PL surface 4s and a movable-side PL surface 5s) are provided on the fixed mold 4 and the movable mold 5. The PL surfaces 4s and 5s are arranged parallel to each other and facing each other.

[0016] For example, the movable mold 5 is moved in the joining direction D2 by a platen, and the movable mold 5 is joined to the fixed mold 4. As a result, the PL surfaces 4s, 5s of both molds come into planar contact with each other without any gaps. As a result, the pair of molds (the fixed mold 4 and the movable mold 5) are maintained in a closed state. In this state, the cavity 2 and the sprue runner 3 are formed inside the pair of molds (the fixed mold 4 and the movable mold 5).

[0017] At this time, molten resin is injected from an injection molding machine (not shown) into the inside of molds 4 and 5. The molten resin flows into cavity 2 from sprue runner 3. As a result, a product that follows the contour of cavity 2 is molded.

[0018] Next, the platen moves the movable mold 5 in the separation direction D1 to separate the movable mold 5 from the fixed mold 4. This causes the PL surfaces 4s, 5s of both molds to move away from each other. As a result, the pair of molds (fixed mold 4, movable mold 5) is maintained in an open state (mold open state). In this state, the molded product (hereinafter referred to as the molded article) can be removed from inside the pair of molds (fixed mold 4, movable mold 5).

[0019] Furthermore, the mold structure 1 is provided with a product nesting unit 6 that constructs the cavity 2, a support nesting unit 7 that constructs the sprue runner 3, and a positioning movement means 8 that can simultaneously move both nesting units 6, 7 and position them at preset positions.

[0020] The product insert unit 6 is configured to include a plurality of product inserts 6a to 6d. Each of the product inserts 6a to 6d is set to a shape and size that can be housed inside a pair of molds (fixed mold 4, movable mold 5). The shape, size, and arrangement of the product inserts 6a to 6d are not particularly limited here, as they can be set arbitrarily depending on, for example, the application and purpose of the pair of molds (fixed mold 4, movable mold 5).

[0021] 1 shows, as an example, an arrangement of a plurality of product nests 6a to 6d each having a rectangular cross section. The product nest unit 6 is formed by arranging the plurality of product nests 6a to 6d adjacent to one another. The cavity 2 is formed in a space (gap) surrounded by the plurality of product nests 6a to 6d arranged adjacent to one another.

[0022] The support nest unit 7 is configured to include a plurality of support nests 7a to 7f. Each of the support nests 7a to 7f is set to a shape and size that can be housed inside the pair of molds (fixed mold 4, movable mold 5). The shape, size, and arrangement of the support nests 7a to 7f are not particularly limited here, as they can be set arbitrarily depending on, for example, the application and purpose of the pair of molds (fixed mold 4, movable mold 5).

[0023] 1 shows, as an example, an arrangement of a plurality of support nests 7a-7f each having a rectangular cross section. The support nest unit 7 is formed by arranging the plurality of support nests 7a-7f adjacent to one another. The sprue runner 3 is constructed in a portion (area) surrounded by the plurality of support nests 7a-7f arranged adjacent to one another.

[0024] The support nesting unit 7 supports the product nesting unit 6 so that it can move in a preset direction. In the example of Fig. 1, the preset direction is set parallel to the contact direction (separation direction D1, joining direction D2) in which the pair of molds (fixed mold 4, movable mold 5) are moved relatively close to and apart from each other.

[0025] In this case, when viewed in a direction perpendicular to the contact directions D1 and D2 (in other words, in a direction along the parting line (PL) surfaces 4s and 5s), it is preferable that the support nest unit 7 is arranged adjacent to the pair of molds (fixed mold 4, movable mold 5) on both sides with no gaps, and it is also preferable that the product nest unit 6 and the support nest unit 7 are arranged adjacent to each other with no gaps.

[0026] Furthermore, it is preferable that the areas where the pair of molds (fixed mold 4, movable mold 5) and the support nest unit 7 are adjacent, and the areas where the product nest unit 6 and the support nest unit 7 are adjacent, be set so that the frictional resistance (friction coefficient) is small.

[0027] As a result, inside the pair of molds (fixed mold 4, movable mold 5), the product nesting unit 6 can be moved smoothly without rattle along the contact and separation directions D1 and D2 by the positioning movement means 8 described later, while being supported by the support nesting unit 7.

[0028] When the pair of molds (fixed mold 4, movable mold 5) are separated from each other, the positioning and moving means 8 simultaneously moves the product nesting unit 6 and the support nesting unit 7 in opposite directions to position them at a predetermined position.

[0029] Here, the timing of separating the pair of molds (fixed mold 4, movable mold 5) relative to one another (i.e., the separation timing) can be, for example, the timing of removing the molded product from inside the molds 4, 5 after the molding process is completed, or the timing of increasing the capacity of the cavity 2 during the molding process.

[0030] Furthermore, the mutually opposite directions can be defined as directional components including one direction and another direction (180° opposite from the one direction). For example, when viewed in the contact and separation directions (separation direction D1, joining direction D2) of a pair of molds (fixed mold 4, movable mold 5), it can be assumed that the product nesting unit 6 is moved in one direction (i.e., the direction along the joining direction D2) and the support nesting unit 7 is moved in the other direction (i.e., the direction along the separation direction D1).

[0031] The positioning and moving means 8 includes a nested product member biasing mechanism 8a and a support nested product member biasing mechanism 8b. The nested product member biasing mechanism 8a constantly biases the nested product unit 6 in one direction (along the joining direction D2). The support nested product member biasing mechanism 8b constantly biases the support nested product unit 7 in the other direction opposite the one direction (along the separating direction D1).

[0032] Such biasing mechanisms 8a, 8b may be, for example, spring members (e.g., coil springs) that apply a biasing force (pressing force, traction force) by utilizing elastic force, spring members that apply a biasing force (pressing force, traction force) by utilizing water pressure or air pressure, or a type that applies a biasing force (pressing force, traction force) by using an electric force to protrude and retract a butting pin 10 described below.

[0033] 1 shows, as an example, a product nesting biasing mechanism 8a (hereinafter referred to as product nesting coil spring 8a) and a support nesting biasing mechanism 8b (hereinafter referred to as support nesting coil spring 8b), which use coil springs that apply a pressing force by utilizing elastic force. Note that the positions and numbers of the product nesting coil springs 8a and the support nesting coil springs 8b are not particularly limited here, as they can be arbitrarily set depending on, for example, the size of the pair of molds (fixed mold 4, movable mold 5) and the arrangement configuration of the product nesting unit 6 and the support nesting unit 7.

[0034] One end of the product insert coil spring 8a is attached to the movable mold 5, and the other end is attached to the product insert unit 6. One end of the support insert coil spring 8b is attached to the fixed mold 4, and the other end is attached to the movable plate 9. As the attachment method, for example, an existing attachment method such as adhesive bonding or screw fastening can be applied.

[0035] The movable plate 9 extends in a direction perpendicular to the contact and separation directions D1 and D2 (a direction along the parting line (PL) surfaces 4s and 5s), and applies the pressing force of the supporting nest coil spring 8b uniformly over the entire supporting nest unit 7. This makes it possible to move the supporting nest unit 7 parallel to the contact and separation directions (separating direction D1, joining direction D2).

[0036] 1 shows a state in which a pair of molds (a fixed mold 4 and a movable mold 5) are joined relative to each other, i.e., the PL surfaces 4s and 5s of both molds are in planar contact with each other without any gaps. This maintains the pair of molds (a fixed mold 4 and a movable mold 5) in a closed state (mold closed state). At this time, the product nesting coil spring 8a constantly presses the product nesting unit 6 in one direction (a direction along the joining direction D2, a direction toward the fixed mold 4). The support nesting coil spring 8b constantly presses the support nesting unit 7 in the other direction (a separation direction D1, a direction toward the movable mold 5).

[0037] In this state, the positioning movement means 8 is equipped with a butt pin 10 that abuts against the product nesting unit 6. The butt pin 10 positions the product nesting unit 6 with respect to the support nesting unit 7 when the pair of molds (fixed mold 4, movable mold 5) are closed (mold closed state). At this time, the cavity 2 formed in the product nesting unit 6 and the sprue runner 3 formed in the support nesting unit 7 are maintained in a state of communication with each other. As a result, when molten resin is injected into the molds 4, 5 from an injection molding machine (not shown), the molten resin flows from the sprue runner 3 into the cavity 2.

[0038] The butt pin 10 extends from the movable mold 5 toward the fixed mold 4. The base end of the butt pin 10 is fixed to the movable mold 5, and the tip end is positioned facing the product nesting unit 6. The overall length of the butt pin 10 is not particularly limited here, as it can be set arbitrarily depending on, for example, the size of the pair of molds (fixed mold 4, movable mold 5) and the arrangement and configuration of the product nesting unit 6.

[0039] The arrangement positions and number of the butt pins 10 are not particularly limited as long as they can support the product inserting unit 6, and can be set arbitrarily, for example, depending on the pressure generated inside the mold. In Fig. 1, as an example, the butt pins 10 are arranged so as to be inserted into the product inserting coil springs 8a. This allows the butt pins 10 to function as guides when the product inserting coil springs 8a elastically expand and contract, and as a result, the product inserting coil springs 8a can elastically expand and contract stably in a fixed direction.

[0040] However, depending on the level of holding pressure to prevent backflow of the molten resin poured into cavity 2 and the level of clamping force when closing a pair of molds (fixed mold 4, movable mold 5), some of the molten resin poured into cavity 2 may flow out of cavity 2 and appear as burrs 11 on the part of the support nest unit 7 adjacent to cavity 2.

[0041] Therefore, the mold structure 1 of this embodiment is provided with a mechanism for improving the accuracy or efficiency of removing burrs 11. That is, the support nest unit 7 has a portion where a plurality of support nests (for example, two support nests 7e, 7f) are in surface contact with each other so as to be adjacent to the cavity 2. As a result, burrs 11 are generated in a state where they are sandwiched and held between the support nests 7e, 7f that are in surface contact with each other. As an example, FIG. 1 shows a state where burrs 11 are generated on a molded product due to molten resin flowing out between the support nests 7e, 7f adjacent to the cavity 2.

[0042] In this case, one example of a method for removing burrs 11 is to simultaneously move the product nesting unit 6 and the support nesting unit 7 in opposite directions when separating a pair of molds (fixed mold 4, movable mold 5) relative to each other (i.e., when opening molds 4 and 5), as shown in Figure 2.

[0043] Fig. 2 is a diagram showing the internal configuration of the mold structure 1 when the molds 4 and 5 are open (mold open state), and the lower half of the figure also shows the internal configuration, focusing on the cavity 2 and the sprue runner 3. Fig. 2 also shows the state in which the pair of molds (fixed mold 4 and movable mold 5) are relatively separated (i.e., the state in which the molds 4 and 5 are open).

[0044] As shown in Figure 2, when the pair of molds (fixed mold 4, movable mold 5) are separated from each other, at that time, the elastic forces of the product nesting coil spring 8a and the support nesting coil spring 8b simultaneously press the product nesting unit 6 and the support nesting unit 7 in opposite directions.

[0045] At this time, the product nest unit 6 (specifically, the product nests 6a and 6c) is pressed by the product nest coil spring 8a, which causes it to move in one direction (along the joining direction D2) together with the cavity 2 into which the molten resin has been poured. At the same time, the support nest unit 7 (specifically, the support nests 7b, 7d, and 7f and the movable plate 9) is pressed by the support nest coil spring 8b, which causes it to move in the other direction (along the separating direction D1) together with the sprue runner 3 and burrs 11.

[0046] At this time, the shear force generated between the product nesting unit 6 and the support nesting unit 7, which are moving in opposite directions, acts on the burr 11, causing it to slide completely out of the cavity 2, and on the sprue runner 3, causing it to move away from the cavity 2. As a result, the sprue runner 3 and the burr 11 are simultaneously separated from the cavity 2 into which the molten resin has been poured.

[0047] Here, the spring constant of the product insert coil spring 8a and the spring constant of the support insert coil spring 8b will be considered. [Prerequisites] The mold opening distance when the pair of molds (fixed mold 4 and movable mold 5) is opened (i.e., when the molds 4 and 5 are separated) is defined as D [m]. The clamping force is F [N]. Two coil springs 8a for the product insert and two coil springs 8b for the support insert are installed, and are set to have their natural lengths when the pair of molds (fixed mold 4, movable mold 5) are relatively separated. As a result, when the pair of molds (fixed mold 4, movable mold 5) are relatively joined, the amount of contraction (distance) of each coil spring 8a, 8b becomes the mold opening distance D [m]. The shear strength of the molten resin is Q [Pa]. The mold will have two cavities (two burrs, two sprue runners). The total cross-sectional area of ​​the separation points is A C [m 2 ]. The load required to push out (move) the product nesting unit 6 is defined as F1. The load required to push out (move) the support nest unit 7 is defined as F2.

[0048] [Requirements] When the mold is closed The load generated in the product insert coil spring 8a and the support insert coil spring 8b is calculated by the forced displacement of the mold opening distance D and the spring constant of each coil spring 8a, 8b. A , K. B F as [N / m] A =2K A D, F B =2K B D. At this time, the relationship with the mold clamping force F [N] is F>F A , F B It is necessary to fulfill the relationship. ·When opening the mold The load generated in the product insert coil spring 8a and the support insert coil spring 8b is F A =2K A D, F B =2K B Therefore, for the coil spring 8a for product inserting, F1 <F A For the coil spring 8b for the support insert, F2 <F B It is necessary to fulfill the relationship. When sprue runner 3 and burr 11 are separated The load required to separate sprue runner 3 and burr 11 is F3 = QA C The load generated in the support insert coil spring 8b when the molds 4 and 5 are separated (when the molds are opened) is F B =2K B D. Therefore, F3 <F B It is necessary to fulfill the relationship.

[0049] [summary] The clamping force when closing the pair of dies (fixed die 4, movable die 5) is F, the load required when moving the product nesting unit 6 in one direction (direction along the joining direction D2, direction approaching the fixed die 4) is F1, and the load acting on the product nesting coil spring 8a when closing the pair of dies (fixed die 4, movable die 5) is F. AThen, the spring constant of the coil spring 8a for inserting the product is F>F A >F1. The clamping force when closing the pair of dies (fixed die 4, movable die 5) is F, the load required when moving the support nest unit 7 in the other direction (separation direction D1, the direction approaching the movable die 5) is F2, the load required to separate the sprue runner 3 and the burr 11 from the cavity 2 is F3, and the load acting on the support nest coil spring 8b when closing the pair of dies (fixed die 4, movable die 5) is F B Then, the spring constant of the support insert coil spring 8b is F>F B They are set to satisfy the relationship: >large(F2, F3), where large(F2, F3) refers to the larger load of either F2 or F3. If there are no coil springs 8a and 8b that satisfy the above-mentioned relationship, the natural lengths of the coil springs 8a and 8b can be changed to adjust the relationship.

[0050] As described above, according to this embodiment, when the pair of molds 4, 5 are separated from one another, the product nesting unit 6, which forms the cavity 2, and the support nesting unit 7, which forms the sprue runner 3, are simultaneously moved in opposite directions. At this time, a shear force generated between the product nesting unit 6 and the support nesting unit 7, which are moving in opposite directions, acts on the burr 11 to slide completely out of the cavity 2 and on the sprue runner 3 to move away from the cavity 2. This enables the burr removal and sprue runner removal operations to be performed simultaneously with the mold opening operation. As a result, the sprue runner 3 and the burr 11 can be simultaneously separated from the cavity 2 into which molten resin has been poured, using only the mold, without any additional work. This realizes a mold structure 1 that allows the burr removal and sprue runner removal operations to be performed easily, quickly, and at low cost.

[0051] According to this embodiment, the support nest unit 7 has a portion where a plurality of support nests (for example, two support nests 7e, 7f) are in planar contact with each other, adjacent to the cavity 2. As a result, the burrs 11 are generated in a state where they are sandwiched and held between the support nests 7e, 7f that are in planar contact with each other. As a result, the cutting accuracy of the burrs 11 can be improved.

[0052] According to this embodiment, the butt pin 10 is arranged to be inserted into the product nesting coil spring 8a. This allows the butt pin 10 to function as a guide when the product nesting coil spring 8a elastically expands and contracts. As a result, the product nesting coil spring 8a can elastically expand and contract stably in a fixed direction.

[0053] "Variations" Figure 3 is a diagram showing the internal structure of the mold structure 1 (molds 4 and 5) according to this modified example in an open state (mold open state), and the lower half of the figure also shows the internal structure focusing on the cavity 2 and the sprue runner 3.

[0054] In the above-described embodiment, the product nesting biasing mechanism 8a is assumed to be a product nesting coil spring 8a that constantly presses the product nesting unit 6 in one direction (a direction along the joining direction D2, a direction approaching the fixed mold 4), but instead, a product nesting coil spring 8a that constantly pulls the product nesting unit 6 in one direction (a direction along the joining direction D2, a direction approaching the fixed mold 4) may be used.

[0055] In this case, one end of the product insert coil spring 8a is attached to the fixed mold 4, and the other end is attached to the product insert unit 6. As the attachment method, for example, an existing attachment method such as adhesive bonding or screw fastening can be applied.

[0056] 3, when the pair of molds (fixed mold 4, movable mold 5) are separated from each other, the product nesting unit 6 is pulled by the product nesting coil spring 8a, and is thereby moved in one direction (along the joining direction D2) together with the cavity 2 into which the molten resin has been poured. At the same time, the support nesting unit 7 is pressed by the support nesting coil spring 8b, and is thereby moved in the other direction (along the separating direction D1) together with the sprue runner 3 and burrs 11.

[0057] At this time, the shear force generated between the product nesting unit 6 and the support nesting unit 7, which are moving in opposite directions, acts on the burr 11, causing it to slide completely out of the cavity 2, and on the sprue runner 3, causing it to move away from the cavity 2. As a result, the sprue runner 3 and the burr 11 are simultaneously separated from the cavity 2 into which the molten resin has been poured. Note that the other configurations and effects are the same as those of the above-described embodiment, and therefore a description thereof will be omitted.

[0058] Although one embodiment and modifications of the present invention have been described above, these embodiments and modifications are presented as examples and are not intended to limit the scope of the invention. These embodiments and modifications can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0059] D1...separation direction, D2...joining direction, 1...mold structure, 2...cavity, 3...spull runner, 4...fixed mold, 4s...PL surface, 5...movable mold, 5s...PL surface, 6...product nesting unit, 6a to 6d...product nest, 7...support nesting unit, 7a to 7f...support nest, 8...positioning movement means, 8a...product nesting biasing mechanism (coil spring for product nesting), 8b...support nesting biasing mechanism (coil spring for support nesting), 9...movable plate, 10...butting pin, 11...burr.

Claims

1. The mold structure is provided with a pair of molds that are relatively movable toward and away from each other, a product nesting unit for constructing a cavity for molding a predetermined product; a support nesting unit that movably supports the product nesting unit and constitutes a sprue runner for pouring molten resin into the cavity; and a positioning and moving means for simultaneously moving the product nesting unit and the support nesting unit in opposite directions to position them at a preset position when the pair of molds are separated from each other.

2. The positioning and moving means is a product nesting unit biasing mechanism that constantly biases the product nesting unit in one direction; 2. The mold structure according to claim 1, further comprising a support nest biasing mechanism that constantly biases the support nest unit in another direction opposite to the one direction.

3. the positioning and moving means includes a butt pin that abuts against the product nesting unit when the pair of molds are joined relative to each other, 2. The mold structure of claim 1, wherein the butt pin positions the product nest unit relative to the support nest unit so that molten resin flows from the sprue runner into the cavity.

4. When a part of the molten resin poured into the cavity flows out of the cavity and forms a burr on a part of the support nest unit adjacent to the cavity, the product nesting unit is moved in the one direction together with the cavity into which the molten resin has been poured by the product nesting biasing mechanism, the support nest unit is moved in the other direction together with the sprue runner and the burr by the support nest biasing mechanism; 3. The mold structure according to claim 2, wherein the sprue runner and the burr are simultaneously separated from the cavity into which the molten resin has been poured by the shear force generated between the product nesting unit and the support nesting unit, which move in opposite directions.

5. The support nest unit has a portion where a plurality of support nests are in surface contact with each other so as to be adjacent to the cavity, 5. The mold structure according to claim 4, wherein the burrs are generated when the support inserts are held between each other in a sandwiched state.

6. When a spring member is used as the product nesting unit biasing mechanism, the mold clamping force when closing the pair of molds is F, and the load required to move the product nesting unit in one direction is F. １ The load acting on the product insert biasing mechanism when closing the pair of molds is F Ａ Then, the spring constant of the product insert biasing mechanism is F>F Ａ >F １ are set to satisfy the relationship When a spring member is used as the support nest biasing mechanism, the mold clamping force when closing the pair of molds is F, and the load required when moving the support nest unit in the other direction is F. ２ The load required to separate the sprue runner and the burr from the cavity is F ３ The load acting on the support nest biasing mechanism when closing the pair of molds is F Ｂ Then, the spring constant of the support insert biasing mechanism is F>F Ｂ >large(F ２ , F ３ 5. The mold structure according to claim 4, wherein the relationship is set to satisfy the following:

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