JP6824863B2 - Molding mold - Google Patents

Description

The present invention relates to a molded mold in which a molded product is heat-treated with a plurality of mold blocks fastened with fastening members.

As a mold for molding rubber or synthetic resin, after injecting raw rubber or resin into the mold, the mold is heated to 90 to 180 ° C, and the injected raw material is vulcanized or heat-cured to mold. There is. The mold used in the rubber molding mold apparatus for continuous vulcanization molding described in Patent Document 1 is divided into a plurality of molds, and is located on one of the outermost molds or on the outer side thereof. A screw bush (known trade name: helisert, etc.) is attached to a female screw hole formed in a member that holds the mold, and is fastened with a bolt. This mold is injected with a rubber material at an injection station and then heat-vulcanized to mold a rubber molded product.

Jikkenhei 5-41733 Gazette

By the way, a molding die that is subjected to heat treatment such as vulcanization treatment and heat hardening treatment is made of a material having excellent thermal conductivity. Molding dies made of rubber or synthetic resin are required to be compact, lightweight, and have excellent durability, and a light alloy, for example, an aluminum alloy may be used for the mold block. In the case of a general injection molding die, it is possible to inject and cool the die in a state of being molded by a hydraulic press so that the die block does not open when injecting raw materials such as thermoplastic resin. There are many.

However, when a rubber material or a thermosetting resin material that requires long-term vulcanization is used, the raw material is often injected and heat-treated in a state of being molded with a fastening member such as a bolt. At this time, if the raw material injected together with the molding die is heat-treated, not only the rubber material and the thermosetting resin expand due to heat, but also the mold itself expands due to heat, which is sufficient for the fastening portion of the molding die. Strength is required. When the structure of the molded product becomes complicated, it becomes necessary to hold the molded mold by combining a plurality of mold blocks using a fastening member, a key, or the like. It is common to use a material different from the mold block, especially a high-strength material such as chrome molybdenum steel, for the fastening member and the key. As a result, a plurality of different materials are combined to form one molding die. For example, a mold block made of a lightweight aluminum alloy or the like having excellent thermal conductivity has a larger coefficient of thermal expansion than a fastening member having high tensile strength. That is, when a molding mold is formed by combining a plurality of materials, the coefficient of thermal expansion differs for each material. Therefore, if the coefficient of thermal expansion of the mold block is larger, a strong axial load is generated at the fastening portion during the heat treatment. And distortion occurs.

In particular, when it has a fastening structure in which a male screw of a bolt made of a high-strength material such as high-strength steel is screwed into a female screw formed in a mold block made of an aluminum alloy or the like, it is heated. Due to the difference in thermal expansion during processing, it is locally plastic from the inner side of the female screw of the mold block, that is, from the female screw part of the mold block screwed to the tip of the first thread of the male screw tip of the bolt. Deformation occurs, leading to damage.

For molds that are used repeatedly, after disassembling the mold and taking out the molded product, it is reassembled and the fastening member is tightened each time with the specified torque, so it is said that plastic deformation occurs in the female screw part during heat treatment. , It will be retightened by that amount at the time of the next mold tightening, and eventually it will be plastically deformed to the female screw part to be screwed to the 1st, 1.5th, and 2nd threads of the male screw of the bolt. And the damaged part progresses. As a result, the female screw portion of the mold block is damaged after the number of uses is less than the durability of the mold block that is not subjected to such heat treatment.

In order to prevent damage to the screw portion, it is considered to reduce the load applied to one of the screw threads by increasing the screwing depth (screw length). However, as described above, when the damage to the screw portion is caused by the difference in thermal expansion, the larger the screw length, the more the male screw portion and the gold of the fastening member when the temperature is raised by the heat treatment. The absolute value of the difference in thermal expansion of the screwed portion with the female screw portion of the mold block becomes larger.

When the coefficient of thermal expansion of the mold block in which the female screw hole is formed is larger than the coefficient of thermal expansion of the bolt, the thermal expansion of the female screw portion of the mold block causes the bolt to move axially toward the tip of the male screw portion of the bolt. The displacement in the stretching direction becomes large. That is, the maximum load acts on the female screw portion of the mold block into which the tip portion of the first thread on the male screw tip side of the bolt is screwed. When the material strength of the mold block is lower than the material strength of the bolt, the load acting in the axial direction of the bolt acts as a shear load on the threads of the female thread, and the shear load acts as a shear load, and the shear load acts on the yield of the mold block. If the stress is exceeded, the threads of the female threads will be damaged.

That is, when the coefficient of thermal expansion of the mold block is larger than the coefficient of thermal expansion of the bolt, the phenomenon that the female screw portion of the mold block where the first thread of the tip of the male screw portion of the bolt is screwed is damaged is screwed. Even if the length is increased, it cannot be solved.

Therefore, the present invention has a structure that suppresses deterioration of the fastening portion even when the molding mold in which the raw material is injected and heat-treated is fixed by a fastening member having a smaller coefficient of thermal expansion and higher tensile strength than the mold block. Provide a molded mold.

The molding die of one embodiment according to the present invention is composed of at least two blocks, and adjacent blocks are connected by bolts having a free length of 100 mm or more . One of the adjacent blocks has a female screw hole in which a female screw portion is formed. The female screw hole is open to the other block side. The other adjacent blocks have bolt holes that are open to one block side. The bolt has a smaller coefficient of thermal expansion than the block, and while it is passed through the bolt hole, the male threaded portion provided at the tip is screwed into the female threaded portion of one block, and the edge of the bolt hole of the other block. With the elastic member mounted between the head and the head, a predetermined tightening load is applied between the female screw portion on which the male screw portion acts and the elastic member mounting portion on which the head acts. When the block expands due to heat treatment, the elastic member is maintained so that the load acting on the bolt is equal to or greater than the tightening load and less than the tensile load at which the female thread is destroyed by the shear stress acting in the tightening direction of the bolt. Shrink like. In addition to the two blocks of interest (one and the other block described above), the third and fourth blocks may be further included. The arrangement of the third and fourth blocks with respect to one and the other block is not limited to the first direction (for example, the vertical direction), but is limited to the second direction (for example, the left-right direction) and the third direction (for example, the upper right, lower left, 45). It may be in a plurality of directions such as (degree direction).

At this time, in the above-mentioned molding die, the other block has a counterbore portion for accommodating the elastic member at the edge of the bolt hole on the opposite side to the one block. A retaining ring that is fitted to the inner peripheral surface of the seating portion to hold the elastic member in the seating portion is further provided. Further, it is preferable that the seating portion has a size for accommodating the elastic member and the head of the bolt.

Further, in the above-mentioned molding die, when there are three or more blocks, the blocks arranged in the middle are provided with both bolt holes and female screw holes. The bolt hole and the female screw hole are arranged at positions that do not overlap each other in the tightening direction of the bolt.

Further, in the above-mentioned molding die, the length at which the male screw portion and the female screw portion are screwed is preferably 0.8 D or more and 1.6 D or less when the nominal diameter of the female screw portion is D. .. Alternatively, in the above-mentioned molding die, when the elastic member includes a plurality of disc springs and the nominal diameter of the female screw portion is D, the dimension is 0.5D or less in the tightening direction of the bolt, and 0.005D or more. It is also preferable to have a shrinkage allowance of. The elastic member is composed of a plurality of disc springs, or is composed of a square spring having a square cross-sectional shape of the winding coil portion.

According to the molding mold of one embodiment according to the present invention, the head of a bolt in which a male screw portion is screwed into a female screw portion of a female screw hole formed in one block, and a bolt hole of the other block. An elastic member is attached to the edge of the bolt, and even if the block expands due to heat treatment, the thread of the female thread is destroyed by the tensile load that exceeds the tightening load and acts in the tightening direction of the bolt. Since it shrinks so as to be maintained below the shear load, it is possible to prevent excessive stress from being applied to the female thread portion. As a result, it is possible to prevent the threads of the female thread portion from being deformed when the molding die is repeatedly used, and the service life of the molding die is extended.

Further, the other block has a seating portion for accommodating the elastic member at the edge of the bolt hole on the opposite side to the one block, and the elastic member is seated by being fitted to the inner peripheral surface of the seating portion. According to the molding die of the invention in which the retaining ring for holding the inside of the portion is further provided, when the molding die is repeatedly assembled and disassembled, the elastic member may be forgotten to be attached or the direction of attachment may be incorrect. It is possible to prevent mistakes and improve workability.

Further, according to the molding die of the invention in which the seating portion has a size for accommodating the elastic member and the head of the bolt, three or more blocks overlap with each other in the tightening direction of the bolt. When a molding die is configured, the head of the bolt where the male screw is screwed into the female screw part of the female screw hole of one of the adjacent blocks through the bolt hole provided in the intermediate block is the intermediate block. Since it is buried in, the head of the bolt does not interfere with the block to be attached next, and the assembly work of the molding mold can be performed smoothly.

Further, when the molding mold is composed of three or more blocks with respect to the tightening direction of the bolt, both the bolt hole and the female screw hole are provided in the block arranged in the middle, and the bolt hole and the female screw hole are provided. According to the molding mold of the invention that is arranged at a position where the blocks do not overlap each other, the bolt that connects the blocks that were combined first when assembling each block in order becomes the bolt that connects the blocks that are combined next. Does not interfere.

Further, when the nominal diameter of the female screw portion is D, the molding die of the invention in which the length at which the male screw portion of the bolt and the female screw portion of the female screw hole are screwed is 0.8 D or more and 1.6 D or less. According to the report, even if the male and female threads are made of the same material, the minimum required screw length is secured, and the axial force of the elastic member is adjusted so that the screw length is up to twice that. By setting the stroke, it is possible to achieve the purpose of selecting a light alloy as the material of the mold block in order to provide a lightweight and compact mold. When the male and female threads are made of the same material, the screw length is JIS B 1181 "hexagon nut" style 1 coarse screw M20, with a nominal diameter of 20 and a nut length of 16.9. It is ~ 18.9, which means 0.845D to 0.945D.

Alternatively, when the nominal diameter of the female screw portion is D, the elastic member has a shrinkage allowance of 0.005D or more with a dimension of 0.5D or less in the tightening direction of the bolt, including the case where a plurality of disc springs are used. According to the molded mold of the invention, it is possible to provide a lightweight and compact mold that has a small volume as an elastic member and can be easily stored in a sitting portion, and when processing accuracy is taken into consideration. By ensuring the minimum necessary shrinkage allowance, it is possible to eliminate adverse effects on plastic deformation and damage of the female thread.

According to the molding die of the invention in which the elastic member is composed of a plurality of disc springs, the axial force and stroke of the elastic member can be easily set and the elastic member can be stored compactly.

The exploded perspective view of the molding die of the 1st Embodiment of this invention. A cross-sectional view of the molding die of FIG. 1 cut along the central axis of the assembled fastening member. The cross-sectional view around the fastening member which enlarged the F3 part in FIG. FIG. 3 is an enlarged cross-sectional view of a screw thread in which a male screw portion and a female screw portion of FIG. 3 are screwed together. FIG. 5 is a cross-sectional view schematically showing a state in which the male screw portion of a bolt is screwed into the female screw portion of one block at room temperature by removing the other block and the elastic member from the state of FIG. FIG. 5 is a cross-sectional view schematically showing a state in which the temperature of the male screw portion and the female screw portion is raised in the state of FIG. FIG. 5 is a cross-sectional view schematically showing a state in which a male screw portion and a female screw portion longer than FIG. 5 are screwed together at room temperature. The nominal length of the bolt 13'is the same as that of the bolt 13 in FIG. FIG. 7 is a cross-sectional view schematically showing a state in which the temperature of the male screw portion and the female screw portion is raised in the state of FIG. 7. FIG. 6 is a cross-sectional view schematically showing a state in which a male screw portion is screwed into a female screw portion having fewer threads than in FIG. 7 at room temperature. The lengths of the deleted female threads f0 to f-9 are the same as L in FIG. FIG. 9 is a cross-sectional view schematically showing a state in which the temperature of the male screw portion and the female screw portion is raised in the state of FIG. FIG. 3 is a cross-sectional view schematically showing a state in which an elastic member is removed from the state of FIG. 3 and a male screw portion and a female screw portion are screwed together at room temperature without a gap. FIG. 5 is a cross-sectional view schematically showing a state in which the temperature has been raised from the state of FIG. The plan view of the molding die of the 2nd Embodiment of this invention. FIG. 3 is a cross-sectional view of a molding die along the line F14-F14 in FIG. FIG. 3 is a cross-sectional view of a molding die along the line F15-F15 in FIG. FIG. 3 is a cross-sectional view of a molding die according to a third embodiment of the present invention. FIG. 3 is a cross-sectional view of a molding die according to a fourth embodiment of the present invention. FIG. 3 is a cross-sectional view of a molding die according to a fifth embodiment of the present invention.

<First Embodiment>
The molding die 1 of the first embodiment according to the present invention will be described with reference to FIGS. 1 to 12. The molding die 1 is a mold in which the raw material of the molded product is injected into the cavity 2 and then heat-treated, and is at least two blocks (in the present embodiment, the first block 11 and the second block 11 and the second block. This is a molding die in which blocks 12) are arranged side by side in the first direction and adjacent blocks are connected by bolts 13. Since the shape of the cavity 2 varies depending on the target molded product, the present embodiment will be described with reference to a typical example of the molding die 1 according to the present invention shown in FIG.

FIG. 1 is an exploded perspective view of the molding die 1 and shows a state in which the molding die 1 is opened in two in the first direction. In the illustrated example, the first direction coincides with the vertical direction. The first direction may be a left-right direction or another direction. The molding die 1 includes a first block 11, a second block 12, a bolt 13, and an elastic member 14. In the case of the present embodiment, one adjacent block is the first block 11 which is the lower mold, and the other adjacent block is the second block 12 which is the upper mold.

FIG. 2 shows an assembled state in which the first block 11 and the second block 12 are combined and fixed with bolts 13. The first block 11 and the second block 12 each have recesses 21 and 22 constituting the cavity 2, and the inlet nozzle 31 for injecting the raw material of the molded product into the cavity 2 and the gas inside are discharged. The outlet nozzles 32 are attached to each. The size and location of the inlet nozzle 31 and the outlet nozzle 32 are not limited to the example of FIG.

Generally, as shown in FIG. 1, the inlet nozzle 31 is often arranged at the lower part and the outlet nozzle 32 is arranged at the upper part. The inlet nozzle 31 and the outlet nozzle 32 may be provided on the side wall of the first block 11 or the second block 12 which does not interfere with the female screw hole 111 and the bolt hole 121.

As shown in FIG. 1, the first block 11 has a female screw hole 111 arranged around the recess 21 of the cavity 2. The female screw hole 111 is open to the side of the second block 12 which is the other block. The female screw hole 111 is often provided with a female screw portion 112 having a length of 1.0 to 2.0 D with respect to the nominal diameter D of the screw.

The second block 12 is combined with the first block 11 to form the cavity 2 as shown in FIG. The second block 12 has bolt holes 121 arranged around the recess 22 of the cavity 2. The bolt hole 121 is opened to the first block 11 side so as to communicate with the female screw hole 111.

In the present embodiment, the first block 11 and the second block 12 are made of the same material that is lightweight and has excellent thermal conductivity in consideration of being heat-treated. For example, a high-strength aluminum alloy is used. A certain 7000 series Al-Zn-Mg alloy, specifically A7075P-T6 material of Japanese Industrial Standard "JIS H 4000: 2014 Aluminum and Aluminum Alloy Plates and Stripes", so-called "super duralumin". Is preferable.

The bolt 13 is a so-called "hexagon socket head cap screw" as shown in FIG. 1, and a male screw portion 131 provided at the tip is a female screw hole in a state where the bolt 13 is passed through the bolt hole 121 as shown in FIG. It is screwed into the female screw portion 112 of 111. Further, with the elastic member 14 mounted between the edge of the bolt hole 121 and the head 133 of the bolt 13, the female screw portion 112 on which the male screw portion 131 acts and the elastic member mounting portion on which the head 133 acts. A predetermined tightening load is applied between the two. That is, the bolt 13 tightens and fixes the first block 11 and the second block 12 with a predetermined tightening load. The bolt 13 has a smaller coefficient of thermal expansion than the first block 11 and the second block 12, and is a high-strength material, for example, chrome molybdenum steel used for general bolts. Specifically, the Japanese Industrial Standard " The SCM435 of "JIS G 4105 chrome molybdenum steel" is adopted in this embodiment. As another material, for example, S45C of a general carbon steel material for machine structure (JIS G 4051: 2009) may be manufactured. It is desirable that all of them be manufactured in accordance with Japanese Industrial Standards "JIS B 1051: 2000 Mechanical Properties of Carbon Steel and Alloy Structure Fastening Parts-Part 1: Bolts, Screws and Implantable Bolts".

As described above, in the molding die 1 of the present embodiment, the materials of the first block 11 and the second block 12 forming the cavity 2 of the molded product and the material of the bolt 13 which is combined and connected to each other are used. , Consists of different dissimilar metals.

As shown in FIG. 3, the male screw portion 131 provided at the tip of the bolt 13 passes through the bolt hole 121 of the second block 12 in a state where the first block 11 and the second block 12 are combined. In this state, it is screwed into the female screw portion 112 of the female screw hole 111 of the first block 11. When the nominal diameter of the female screw portion 112 is D, it is desirable that the male screw portion 131 is screwed with respect to the female screw portion 112 in the tightening direction with a length of 0.8 D or more and 1.6 D or less. In the illustrated example, the tightening direction of the bolt 13 coincides with the first direction.

Further, as shown in FIGS. 2 and 3, the bolt 13 has the male screw portion 131 and the head 133 in a state where the elastic member 14 is mounted between the head 133 of the bolt 13 and the edge of the bolt hole 121. It receives a predetermined tightening load between them.

The molding die 1 is heat-treated in a state where the first block 11 and the second block 12 are tightened and fixed with bolts 13 as shown in FIG. At this time, since the coefficient of thermal expansion of the bolt 13 is smaller than that of the first block 11 and the second block 12, a tensile load due to physical displacement due to thermal expansion is applied to the bolt 13. The elastic member 14 prevents a tensile load due to this displacement from being applied to the bolt 13, and prevents a shear load that breaks the female threaded portion 112 from being applied to the female threaded portion 112. That is, in the elastic member 14, when the first block 11 and the second block 12 are expanded by the heat treatment, the load acting on the bolt 13 molds the first block 11 and the second block 12. The female thread portion 112 is shrunk so as to be maintained at an appropriate load equal to or greater than the tightening load for the purpose and less than or equal to the shear load in which the female thread portion 112 is destroyed by the shear stress on the threads acting in the tightening direction.

In this embodiment, as shown in FIG. 3, a disc spring is adopted as the elastic member 14. By adopting a disc spring, the tightening load by the bolt 13 is uniformly applied in the circumferential direction around the axis of the bolt 13. Further, by adopting a plurality of disc springs as the elastic members 14, in order to maintain an appropriate load between the tightening load and the breaking strength, the disc springs are inserted in the same direction and arranged in parallel to maintain the spring constant. It is easy to set the contraction allowance (stroke) by inserting the disc springs in series so that the inner circumferences and the outer circumferences are in contact with each other alternately. In the present embodiment, as shown in FIGS. 2 and 3, two disc springs are mounted in parallel as the elastic member 14, and when the nominal diameter of the female screw portion 112 is D, the tightening direction is changed. It is desirable that the size is 0.5D or less and the shrinkage allowance is 0.005D or more.

Further, in order to facilitate positioning of the elastic member 14, the second block 12 has a counterbore portion 122 larger than the outer shape of the elastic member 14 at the edge of the bolt hole 121 on the opposite side of the first block 11. It is provided. The seating portion 122 has a depth at which the elastic member 14 is completely buried, and after the elastic member 14 is attached, the elastic member 14 is stopped so as not to fall off when the molding die 1 is assembled or disassembled. The ring 15 is mounted. The retaining ring 15 is fitted into a groove carved on the inner peripheral surface of the seating portion 122.

The molding die 1 configured as described above is used to obtain a molded product that requires heat treatment, such as vulcanized rubber and a thermosetting synthetic resin. First, the raw material is injected into the cavity 2 in a state where the first block 11 and the second block 12 are molded with bolts 13, and then the inlet nozzle 31 and the outlet nozzle 32 are sealed. Next, the molding die 1 is heat-treated at a temperature and time suitable for the raw material injected into the cavity 2 to obtain a molded product.

In the molding die 1 of the present invention, the lengths of the male screw portion 131 of the bolt 13 and the female screw portion 112 of the female screw hole 111 to be screwed in the axial direction have been examined in more detail. For the sake of clarity, the material of the first block 11 and the second block 12 is extra super duralumin (A7075), and the material of the bolt 13 is chrome molybdenum steel generally used for hexagon socket head bolts. An example of (SCM435) is shown.

First, a case where the elastic member 14 is not attached will be described. Two failure modes are assumed in the event that the fastening portion is broken when the bolt 13 receives a tensile load in the axial direction while the male screw portion 131 is screwed into the female screw portion 112. One is that the tensile strength [N] of the valley diameter portion of the male screw portion 131 of the bolt 13 is the shear strength [N] along the axial direction of the thread of the female screw portion 112 located at the outer diameter portion of the male screw portion 131. When it is higher than N], it is a fracture mode in which shear fracture of the female thread occurs. The other is that the tensile strength [N] of the valley diameter portion of the male threaded portion 131 of the bolt 13 is the male threaded portion. When the shear strength [N] along the axial direction of the thread of the female thread 112 located in the outer diameter of 131 is lower than the shear strength [N], the bolt 13 breaks at the valley of the male thread. In the case of the present embodiment, the combination of the respective materials is as described above, and the shear strength [N] along the axial direction of the thread of the female thread portion 112 is significantly smaller. Therefore, the fracture mode is the former ". Corresponds to "shear fracture of female threads".

The tensile strength of A7075, which is the material of the first block 11 and the second block 12, is 540 [N / mm ² ] or more when using a 100 mm thick plate of JIS H 4000 "A7075P-T6", and the shear strength is This is about 60% of 324 [N / mm ² ] or more, and the bolt 13 has a tensile strength of 1220 [N / mm ² ] or more when using JIS B 1051 “strength category 12.9” bolts of the material SCM435. .. That is, the shear strength 324 [N / mm ² ] of the female screw portion 112 is 1/3 or less of the tensile strength 1220 [N / mm ² ] of the valley diameter portion of the male screw portion 131.

The temperature range in the heat treatment using the molding die 1 is 120 to 180 [° C.], and the tensile strength of SCM435 is almost the same in this temperature range, whereas the A7075 is heated to about 130 ° C. It is known that the tensile strength and the shear strength are reduced to about 60%. The coefficient of thermal expansion of A7075 is 23.6 × 10 ^-6 / ° C, and the coefficient of thermal expansion of SCM435 is 11.2 × 10 ^-6 / ° C.

The temperature (normal temperature) when assembling the molding die 1 is set to 20 ° C., and the temperature when the vulcanized rubber molded by the molding die 1 is heat-treated is set to 130 ° C. Further, the length of the bolt head 133 is subtracted from the total length of the bolt 13 which is a hexagon socket head cap screw to obtain the nominal length of the bolt, and then the length of one screw thread at the tip of the bolt of the male screw portion 131 (1 pitch). Assuming that the free length L of the bolt 13 is the dimension obtained by subtracting the length), the free length L of the bolt 13 is the female screw of the first block 11 which is expanded more than the bolt 13 due to the difference in thermal expansion at the heat treatment temperature. From the portion where the thread of the portion 112 abuts and is restrained by the thread at the tip of the bolt of the male thread portion 131, the second block 12 which is expanded more than the bolt 13 due to the difference in thermal expansion at the heat treatment temperature is the bolt 13. It is the same as the unrestrained length up to the portion that is in contact with the head 133 and is restrained.

Based on the above conditions, the amount of heat elongation due to each temperature change of 110 ° C. during the heat treatment was calculated. The amount of heat elongation of the second block 12 was 2.596 L × 10 ^-3 mm, and that of the bolt 13. The amount of heat elongation is 1.232 L × 10 ^-3 mm. Therefore, when the free length L = 100 mm, the respective thermal expansion amounts are 0.2596 mm and 0.1232 mm, and the thermal expansion difference is 0.1364 mm.

At this time, the free length L is a portion obtained by removing the thread at the tip of the bolt from the male screw portion 131 of the bolt 13 and a body portion 132 which is a male screw unprocessed portion of the bolt 13. Therefore, the displacement amount (strain) δ of the free length L portion with respect to the tensile load is the displacement amount δ ₁ of the male screw portion 131 excluding the tip 1 thread and the displacement amount δ ₂ of the body portion 132.

If the bolt 13 is a bolt metric coarse thread, the effective diameter of the male screw portion 131 d _2, (nominal diameter of the male screw portion of = V) outer diameter of the body portion 132 when the d, the axis of the bolt 13 effective径断area a _chromatic male threaded portion 131 for pulling exerted on the axial load is represented by ^{_{π (d 2/2) 2}} [mm 2], the cross-sectional area a _out of the body portion 132 π (d / ²⁾ 2 It is represented by [mm ² ]. When the nominal diameter of the male screw portion 131 is d = 12, the effective diameter of the male screw portion 131 is d ₂ = 10.863 mm, and the outer diameter dimension of the body portion 132 (= male screw outer diameter (= nominal diameter)) = 12 since in .00Mm, effective径断area a _Yes = 92.68mm ² of the male screw portion 131, the cross-sectional area of the trunk portion 132 a _out = 113.1 mm ^2. Incidentally, the effective径断area A _chromatic male threaded portion 131 is substantially the average of the valley径断area of the screw valley is threaded outside径断area and the minimum of the thread cross-sectional area is the largest, the male threaded portion It is considered to be the average cross-sectional area of 131.

Here, the difference in thermal expansion (difference in the amount of thermal expansion) between the first block 11 and the second block 12 and the bolt 13 caused by the temperature change during the heat treatment is such that the bolt 13 is the first block 11 during the heat treatment. And it can be regarded as the amount of displacement δ extended by the second block 12. The axial force F acting on the bolt 13 by the displacement amount δ is calculated by the following equation from Young's modulus E, effective cross-sectional area A, length of the portion where the axial force is applied (free length L), and displacement amount δ.

F = (E ・ (A / L)) ・ δ [N]
At this time, the axial force F applied to each of the male screw portion 131 and the body portion 132, which are the free length L portions of the bolt 13, is the same. Therefore, the bolt 13 is in a Young's modulus E = 2.1 × 10 ⁵ when SCM435, a length _L 1 = 10.00 mm male threaded portion 131 which is not restrained in contact with the threads of the female screw portion 112, If the length L ₂ = 90.00mm of the body portion 132, on the basis of the equation for axial force F described above, the axial force exerted on the male screw portion _{131, F 1 = (2.1 × 10} 5 × 92. 68 / 10.00) × δ ₁ [N] = (1.9463 × 10 ⁶ ) δ ₁ [N], the axial force applied to the body 132 is F ₂ = (2.1 × 10 ⁵ × 113.1) It can be calculated as / 90.00) × δ ₂ [N] = (0.2639 × 10 ⁶ ) δ ₂ [N]. F ₁ = _{F 2} so the amount of displacement [delta] is from _{^{(1.9463 × 10 6) δ 1}} = (0.2639 × 10 6) δ 2, the δ ₁ = 0.13559δ _2.

Since the total length of the free length L portion of the bolt 13 is L ₁ + L ₂ = 100 mm, the displacement amount δ is the thermal expansion difference between the first block 11 and the second block 12 corresponding to this, and is the front. As described in the above, it is 0.1364 mm. _{Thus, δ = δ 1 + δ 2} = With _{0.1364mm, δ 1 + δ 2 =} 0.13559δ 2 + δ 2 = 1.13559δ 2 = displacement of the externally threaded portion 131 than 0.1364mm δ ₁ = 0. It can be seen that the displacement amount of the body portion 132 is 01629 mm and the displacement amount δ ₂ = 0.12011 mm. Further, the axial forces obtained from these are F ₁ = 31,705 [N] and F ₂ = 31,697 [N], but since these are originally equal, F = 31.70 [N] in the following explanation. kN] is approximated.

The breaking strength of the bolt 13 is calculated based on the root diameter d ₁ of the male threaded portion 131 = 10.106 mm. Since the tensile strength of SCM435, which is the material of the bolt 13, is 1,220 [N / mm ² ] or more, the bolt 13 having a nominal diameter of M12 has a strength to withstand the maximum axial force Fmax = 97.86 [kN]. ing. Therefore, the safety factor of the bolt 13 with respect to the axial force F (= 31.70 [kN]) generated by the displacement amount δ due to thermal expansion is 3.1 times, but this axial force F is repeatedly applied every time the heat treatment is performed. And affects durability.

In the present embodiment, since the elastic member 14 is mounted between the head 133 of the bolt 13 and the edge of the bolt hole 121 of the second block 12, the difference in thermal expansion is caused by the deformation of the elastic member 14. The axial force F that is absorbed and applied to the free length L portion of the bolt 13 is suppressed to a sufficiently low value.

Next, the axial force Fs applied during the heat treatment to the male screw portion 131 screwed into the female screw hole 111 of the first block 11 will be considered. The axial force F applied to the bolt 13 due to the thermal expansion of the second block 12 is as described above. At this time, the male screw portion 131 of the bolt 13 is screwed into the female screw portion 112 of the female screw hole 111 of the first block 11. At room temperature (normal temperature) when the molding die 1 is assembled, the pitch of the male screw portion 131 is the same as the pitch of the female screw portion 112, and the axial force Fs related to the range in which they are screwed together is the screw of the male screw portion 131. The case where it is assumed that the mountains are evenly distributed will be described.

The axial force Fs applied to the entire male screw portion 131 of the bolt 13 during the heat treatment is the same as the second block 12 in addition to the tightening load for molding the first block 11 and the second block 12. Axial force F generated by the difference in thermal expansion from the free length L portion of the bolt 13 is also applied, and the axial direction (first) is applied between the thread of the male threaded portion 131 and the thread of the female threaded portion 112 of the female threaded hole 111. Acts as a shear load (in the direction of). When evaluating the destruction of the threaded portion (male threaded portion 131, female threaded portion 112), the shear load related to the thread of the male threaded portion 131 and the shearing load related to the thread of the female threaded portion 112 are the respective materials. It is judged by whether or not it exceeds the shear strength.

Effective area A _M with respect to the axial direction of the shear load threaded receiving the male threaded portion 131 of the bolt 13, the tip is consuming position of the thread of the female screw portion 112 relative to the screw thread of the male threaded portion 131 (i.e. female It is calculated as the area to be cut by the cylindrical surface of the inner diameter D ₁₎ of the threaded portion 112. Further, the effective cross-sectional area _{AF with} respect to the axial shear load received by the thread of the female thread 112 is the position where the tip of the thread of the male thread 131 hangs on the thread of the female thread 112 (that is, the male thread). It is calculated as the area cut out on the cylindrical surface in the outer diameter d) of the portion 131.

FIG. 4 is an enlarged sectional view schematically showing a portion where the male screw portion 131 and the female screw portion 112 are screwed together. The male threaded portion 131 and the female threaded portion 112 shown in FIG. 4 show an example in which the nominal diameter of "JIS B 0205: 2001 general metric screw part 4: reference dimension" is 12 and the pitch is 1.75. Thread pitch P = 1.75 mm, female screw portion 112 inner diameter D ₁ = 10.106 mm, male screw portion 131 outer diameter d = 12.00 mm, female screw effective diameter D ₂ and male screw effective diameter d ₂ = 10 It is .863 mm.

In FIG. 4, assuming that the line segment tu that crosses the male thread portion 131 thread in the axial direction at the position of the inner diameter of the female thread portion 112, the angle α of the thread is 60 degrees, so when the nominal diameter is M12, the line The minute tu = (P / 2) + ((d _2- D ₁ ) / tanα) = 1.312 mm. In this case, the effective cross-sectional area _{A M} with respect to the axial direction of the shear load of 1 pitch of the screw thread in the male screw portion 131 is _{A M} = segment _{tu × D 1 × π = 41.66mm} 2. Further, assuming that the line segment vw that crosses the thread of the female screw portion 112 in the axial direction at the position of the outer diameter d of the male screw portion 131, the line segment vw = (P / 2) + ((d−D ₂ ) / tanα ) = 1.531 mm. At this time, the effective cross-sectional area _AF of the female thread portion 112 with respect to the shear load in the axial direction of the thread of one pitch is _AF = line segment vw × d × π = 57.73 mm ² .

Comparing the effective cross-sectional area with respect to the axial direction of the shear load as described above, towards the effective area A _F of the thread of the female screw portion 112 than the effective cross-sectional area A _M of the thread of the male screw portion 131 is about 40 %large. Therefore, when the male screw portion 131 and the female screw portion 112, which are general cases, are made of the same material (co-material), the male screw portion 131 is sheared and fractured first. The male screw portion 131 and the female screw portion 112 are fastened by screwing not only one pitch but also a plurality of pitches. Therefore, in order to prevent the thread of the male threaded portion 131 from being destroyed, the shear strength = "the male threaded portion 131" rather than "tensile strength at the _valley diameter of the male threaded portion 131 = [cross-sectional area A _valley ] x [tensile strength]". The number of screwing pitches (screw length = screw length) is set so that [effective cross-sectional area _AM ] × [shear strength] with respect to the shear load of the screw thread becomes larger.

In the case of this embodiment, the material of the bolt 13 is SCM435, and the material of the first block 11 and the second block 12 is A7075. As described above, the tensile strength of SCM435 is 1,220 [N / mm ² ] or more, the shear strength is about 60% of this, 732 [N / mm ² ] or more, and the shear strength of A7075 is room temperature (20). ℃) is 324 [N / mm ² ] or more.

The molding die 1 is heated to a temperature of 120 to 180 ° C. during the heat treatment. The tensile strength of SCM435 is almost the same as that of heat treatment at this temperature, whereas the tensile strength of A7075 decreases to about 60% of that at room temperature when the temperature rises to 130 ° C. Therefore, the shear strength is also considered. And 194 [N / mm ² ] or more. As a result, when the heat treatment mold 1, the axial force _{F MP,} which can be held in one pitch of the thread of the male threaded portion 131, whereas it is 30.50 [kN], the female screw portion 112 The axial force F _FP that can be held by a screw thread of one pitch is 11.20 [kN].

Therefore, in the molding mold 1, the screw thread of the female screw portion 112 screwed into the male screw portion 131 is used so that the female screw portion 112 of the female screw hole 111 provided in the first block 11 is not destroyed. breaking strength of the axial force _{F F} is the bolt 13 to hold (97.86 [kN]) to be greater than, consider number of pitches of the screw thread of the male screw portion 131 and the female screw portion 112 is screwed ..

The molding die 1 is repeatedly assembled, heat-treated, and disassembled each time a molded product is manufactured. By repeating this manufacturing process, the bolt 13 repeats the same thing as receiving a so-called one-sided repetitive load.

In general, in fatigue fracture due to the repeated load of one-sided swing of steel, the safety factor when the repeating cycle is short is set to "5 times", and the safety factor when the repeating cycle is long and close to the static load is "3 times". Is set to. In the case of the molding mold 1 of the present embodiment, assembling, heating, and disassembling are repeated, but the cycle in which the load is applied to the male screw portion 131 and the female screw portion 112 by the repetition is long, which is close to a static load. Therefore, the safety rate of the female screw portion 112 is set to 3 times, and the bolt is used to hold the axial force F (31.70 [kN]) generated in the bolt 13 by the thermal expansion of the heat treatment in the female screw hole 111. The number of pitches required for the female screw portion 112 to be screwed with the male screw portion 131 of 13 is calculated to be 8.49 pitches. Assuming that the number of pitches required to triple or more the safety factor is 9, one pitch of the bolt 13 having a nominal diameter of M12 is 1.75 mm, so the male screw portion 131 and the female screw portion 112 are screwed together. The length needs to be 15.75 mm (about 1.3D). The safety factor (95.1 kN) of the axial force F (31.70 [kN]) generated in the bolt 13 due to thermal expansion is almost the same as the breaking strength (97.86 [kN]) of the bolt 13. became.

That is, assuming that the axial force Fs related to the screwed range is evenly distributed to each of the threads of the male threaded portion 131 and the female threaded portion 112, the nominal diameter D of the female threaded portion 112 D. If the female threaded portion 112 having a length of about 1.3 D in the axial direction is screwed into the male threaded portion 131 of the bolt 13 as an effective threaded portion, the axial force F is increased due to the difference in thermal expansion in the heat treatment. Even if it occurs, the threaded portion of the female screw portion 112 of the bolt 13 and the first block 11 is held without being broken.

By the way, the first block 11 on which the female screw portion 112 is formed and the male screw portion 131 of the bolt 13 also thermally expand, and the male screw portion 131 of the bolt 13 also has a tensile load of axial force F for each pitch of the screw thread. Receive and displace. That is, the load borne by each thread and the amount of displacement due to the thread of the male thread 131 screwed to the female thread 112 are the number of the thread from the head 133 side of the bolt 13. As a result, the shear load acting on each thread is also different.

Therefore, with reference to FIGS. 5 and 6, FIGS. 7 and 8, 9 and 10, and 11 and 12, the load acting between the individual threads of the male threaded portion 131 and the female threaded portion 112. Consider. In addition, in order to make it easy to understand the mechanism of the present application, FIGS. 5 to 12 have been simplified by shortening the length of the body 132 of the bolt 13 of FIGS. 1 to 3 of the present embodiment.

In FIGS. 5 and 6, and 11 and 12, the male threaded portion 131 of the bolt 13 is in a state in which nine threads from the tip are screwed into the female threaded portion 112. Therefore, the first thread on the head 133 side of the male threaded portion 131 of the bolt 13 hanging on the female threaded portion 112 is set as the first thread m1, and the second thread m2, the third thread m3, ... , 9th mountain m9. Similarly, for the thread of the female screw portion 112, when the bolt 13 is pulled out to the head 133 side in order from the outermost side (hole opening side) of the female screw hole 111 facing the second block 12 side. The one screwed into the first thread m1 of the male screw portion 131 is the first thread f1, the one screwed into the second thread m2 of the male screw portion 131 is the second thread f2, and thereafter, the third thread f3, ... , 9th mountain f9. Further, the screw thread on the head 133 side of the male screw portion 131 with respect to the first thread m1 is set to the zero thread m0.

Similarly, in FIGS. 7 and 8, the first block 11 is large and the female screw portion 112 is long, and the bolt 13 has no body portion 132 and is all male screw portion 131. It is the figure of the state that all the ridges are screwed to the female thread part 112. Therefore, the first thread on the head 133 side of the male threaded portion 131 of the bolt 13 hanging on the female threaded portion 112 is set to the -9th thread m-9, and the -8th thread m-8 toward the tip, The 7th mountain m-7, ..., the zeroth mountain m0, ..., The 9th mountain m9. Similarly, for the thread of the female screw portion 112, a male screw is used when the bolt 13 is pulled out to the head 133 side in order from the outermost side (hole opening side) of the female screw hole 111 facing the bolt head 133 side. The one that contacts the -9th thread m-9 of the portion 131 is the -9th thread f-9, and the one that contacts the -8th thread m-8 of the male threaded portion 131 is the -8th thread f-8. Hereinafter, it will be referred to as a -7th mountain f-7, ..., a zeroth mountain f0, ... a 9th mountain f9.

The following figures in FIGS. 9 and 10 show that the female screw portion 112 of the first block 11 in FIGS. 7 and 8 does not have 10 threads from the -9th thread m-9 to the zero thread m0. It is a figure of a state in which the same bolt 13 as in FIGS. 7 and 8 is used and screwed to the female screw portion 112 to the maximum extent. Therefore, as in FIGS. 5 and 6, the first screw thread on the head 133 side of the male screw portion 131 of the bolt 13 screwed into the female screw portion 112 is set to the first thread m1 and the last screw toward the tip. Let the mountain be the 9th mountain m9. Similarly, for the thread of the female screw portion 112, a male screw is used when the bolt 13 is pulled out to the head 133 side in order from the outermost side (hole opening side) of the female screw hole 111 facing the bolt head 133 side. The one that contacts the first thread m1 of the portion 131 is referred to as the first thread f1, and the one that contacts the ninth thread m9 of the last male screw portion 131 is referred to as the ninth thread f9. Further, the screw thread on the head 133 side of the male screw portion 131 with respect to the first thread m1 is set to the zero thread m0.

In the schematic cross-sectional view of FIGS. 5, 7, 9, and 11, the third block is between the male screw portion 131 and the female screw portion 112, and between the first block 11 and the second block 12. There is a gap between the block 11 or the second block 12 of 1 and the head 133 of the male screw portion 131 of the bolt 13, but for explanation, a load acts to push them against each other (contacting each other). It is schematically shown with a large gap so that it is easy to understand where the screw thread is and where the surface where the load acts and presses against each other. There is only a rush gap, and the male screw portion 131 is screwed into the female screw portion 112 with almost no gap, and the gap between the surface of the block 11 and the surface of the block 12 is also the gap of the back crush. It is assumed that they are about the same. Further, all the gaps are the same as the slight gaps between these threads and the slight gaps between the surfaces. Further, FIGS. 6, 8, 10, and 12 are similar schematic cross-sectional views.

5 and 6 show a state in which a bolt 13 is screwed into the first block 11 without assembling the second block 12, FIG. 5 shows a state at room temperature, and FIG. 6 shows heating to the same temperature as the heat treatment. Each of these states is shown schematically as a cross-sectional view. Further, in FIGS. 7 and 8, the female screw portion 112 of the first block 11 is attached to the long block 11'by "the amount equivalent to the incorporation of the second block 12", and the bolt 13 has a male screw portion up to the body 132. A state in which the "131" bolts 13'are combined with almost no gap, FIG. 7 shows a state at room temperature, and FIG. 8 shows a state heated to the same temperature as the heat treatment in a schematic cross-sectional view. In the drawings of FIGS. 9 and 10, the bolt 13 is attached to the block 11'"there is no thread of the female screw portion 112 (there is no length corresponding to the incorporation of the second block 12)". 'Is shown in a state in which'is combined with almost no gaps, FIG. 9 shows a state at room temperature, and FIG. 10 shows a state heated to the same temperature as the heat treatment in a schematic cross-sectional view. A cross-sectional view schematically shows a state in which bolts 13 are combined with the first block 11 and the second block 12 with almost no gap, FIG. 11 is a state at room temperature, and FIG. 12 is a state heated to the temperature of heat treatment. In the combined state of the first block 11 and the second block 12 of FIGS. 11 and 12, the first block 11 of FIGS. 9 and 10 is referred to as the thread number of the male screw portion 131. It is substantially the same as the state in which the two are cut and separated at the apex position of the zero peak m0.

FIGS. 7, 9 and 11 are views when a tightening load is not applied so that the bolt 13 is stretched during mold assembly, and a large gap is shown for easy understanding in the explanation, but FIG. 5 Similar to the above, it is a slight gap equivalent to the backlash of the screwed portion.

First, with reference to FIGS. 5 and 6, the axial force generated between the male screw portion 131 and the female screw portion 112 due to the temperature difference due to the heat treatment will be described. When the temperature of the molding die 1 begins to rise due to the heat treatment, the head 133 of the bolt 13 is not engaged with the second block 12, and there is nothing that restrains the male screw portion 131 and the female screw portion 112 to each other. Therefore, as shown in FIG. 6, the center of the range in which the male screw portion 131 and the female screw portion 112 are screwed can be considered as the neutral point X1. Strictly speaking, at the heat treatment temperature shown in FIG. 6, the first thread f1 of the female screw portion 112 and the male screw portion 131 where the threads are brought into contact with each other and restrained by receiving a load due to a difference in thermal expansion. The number of threads is 8.5, which is the range from the center of the contact portion of the zeroth thread m0 to the center of the contact portion of the ninth thread f9 of the female thread portion 112 and the ninth thread m9 of the male thread portion 131. The center of the mountain is the neutral point X1.

When the temperature rise is started from the normal temperature state shown in FIG. 5 to the heating temperature shown in FIG. 6, the first block 11 and the bolt 13 are not constrained to each other, and therefore expand evenly according to their respective thermal expansion coefficients. Since the coefficient of thermal expansion of the first block 11 is larger than the coefficient of thermal expansion of the bolt 13, the female screw portion 112 extends more axially than the male screw portion 131. As a result, due to the difference in the coefficient of thermal expansion, the first thread f1 of the female thread portion 112 is axially pressed against the zero thread m0 of the male thread portion 131, and the ninth thread f9 of the female thread portion 112 is the male screw. It presses against the ninth mountain m9 of the portion 131 in the axial direction. At this time, when the cross-sectional areas of the bolt 13 and the block 11 in the axial direction are compared, the cross-sectional area of the bolt 13 is overwhelmingly small, so that the male screw portion 131 receives the axial force F1 stretched in the axial direction.

Next, with reference to FIGS. 7 and 8, the axial force generated between the male screw portion 131 and the female screw portion 112 due to the temperature difference due to the heat treatment will be described. The only difference from FIGS. 5 and 6 is that the female screw portion 112 of the first block 11 is long and the long bolt 13'without a body is combined with almost no gap, and all the others are the same. is there. When the temperature of the molding die 1 begins to rise due to the heat treatment, backlash occurs between the faces of the head 133 of the bolt 13'and the first block 11'and the threads of the male threaded portion 131 and the female threaded portion 112. Since there is a similar gap and there is nothing that restrains the bolt 13'and the first block 11'to each other, as shown in FIG. 8, the center of the range in which the male screw portion 131 and the female screw portion 112 are screwed together. Can be considered as the neutral point X2. Strictly speaking, the same applies from the contact portion between the head 133 of the bolt 13 and the first block 11 where the surfaces are brought into contact with each other and restrained by receiving a load due to the difference in thermal expansion at the heat treatment temperature shown in FIG. The range is from the 9th thread f9 of the female screw portion 112 and the center of the contact portion of the 9th thread m9 of the male screw portion 131 where the threads are brought into contact with each other and restrained by receiving a load due to the difference in thermal expansion. The center of the 18.75 threads in terms of the number of threads is the neutral point X2. In this way, the range of 8.5 peaks in the cases of FIGS. 5 and 6 has expanded to the range of 18.75 peaks, so this neutral point is called X2.

When the temperature rise is started from the normal temperature state shown in FIG. 7 to the heating temperature shown in FIG. 8, the first block 11'and the bolt 13' are not constrained to each other, and therefore expand evenly according to their respective thermal expansion coefficients. .. Since the coefficient of thermal expansion of the first block 11'is larger than the coefficient of thermal expansion of the bolt 13', the female screw portion 112 extends more axially than the male screw portion 131. As a result, due to the difference in the coefficient of thermal expansion, the contact portion between the head 133 of the bolt 13'and the first block 11' is pressed in the axial direction, and the ninth thread f9 of the female screw portion 112 is the male screw portion. It pushes against the ninth mountain m9 of 131 in the axial direction. At this time, when comparing the cross-sectional areas of the bolt 13'and the block 11'in the axial direction, the cross-sectional area of the bolt 13'is overwhelmingly small, so that the male screw portion 131 receives the axial force F1 stretched in the axial direction. .. When the difference between the coefficients of thermal expansion of the bolt 13'and the first block 11'is α, the elongation is α × 8.5 peaks in the cases of FIGS. 5 and 6, and in the cases of FIGS. 7 and 8. Although the elongation amount of α × 18.75 peaks and the latter is large, the elongation rate (strain) is the same α. Therefore, since the cross-sectional area of the bolt 13 and the longitudinal elastic modulus E (Young's modulus) are the same and the elongation rate (strain) is also the same, the axial force that stretches the bolt 13 in the axial direction receives the same axial force F1 as the former. It will be.

Further, with reference to FIGS. 9 and 10, the axial force generated between the male screw portion 131 and the female screw portion 112 due to the temperature difference due to the heat treatment will be described. The difference from FIGS. 7 and 8 is that the female screw portion 112 of the first block 11'is 10 threads from the outermost side (hole opening side) of the female screw hole 111 facing the head 133 side of the bolt 13. I just lost it, everything else is the same. The length of these 10 peaks corresponds to the length of the second block 12. When the temperature of the molding die 1 starts to rise due to the heat treatment, there is nothing that restrains the bolt 13'and the first block 11 "to each other as in FIGS. 7 and 8, and therefore, as shown in FIG. 10, the bolt The range is from the contact portion between the head 133 of 13'and the first block 11 "to the center of the contact portion between the 9th thread f9 of the female screw portion 112 and the 9th thread m9 of the male screw portion 131. The center of 18.75 threads in terms of the number of threads is the neutral point X2.

When the temperature starts to rise from the room temperature state shown in FIG. 9 to the heating temperature shown in FIG. 10, there is nothing that constrains the first block 11 "and the bolt 13'to each other as in FIG. 8, so that the respective thermal expansion coefficients are set. Therefore, it expands evenly, and the female screw portion 112 expands more in the axial direction than the male screw portion 131. As a result, due to the difference in the coefficient of thermal expansion, the male screw portion 131 expands in the axial direction as in FIG. As the axial force stretched to, the same axial force F1 as in FIGS. 6 and 8 is received.

11 and 12 to be described last are the same combination as that of the first embodiment, and in this case, the axial force generated between the male screw portion 131 and the female screw portion 112 due to the temperature difference due to the heat treatment will be described. To do. The difference from FIGS. 9 and 10 is that the first block 11'is divided into two at the position of the apex of the zero thread m0 of the male thread portion 131, and the one having the female thread 112 is the first. The block 11 is called, and the one without it is called the second block 12, but the others are basically the same. (The division position of the first block 11'is the same position as between the first thread f1 and the zero thread f0 of the female thread portion 112 of the first block 11'in FIG. 7.)
When the temperature of the molding die 1 starts to rise due to the heat treatment, the first block 11, the second block 12 (the original block 11'is divided), and the bolt 13 are attached to each other as in FIGS. 9 and 10. There is nothing to restrain. Therefore, as shown in FIG. 12, from the contact portion between the head portion 133 of the bolt 13 and the second block 12, the contact portion between the 9th thread f9 of the female screw portion 112 and the 9th thread m9 of the male screw portion 131. The center of 18.75 threads, which is the range to the center, is the neutral point X2.

When the temperature starts to rise from the room temperature state shown in FIG. 11 to the heating temperature shown in FIG. 12, the first block 11 and the second block 12 (the original block 11'is divided) and the bolt 13 are similarly formed in FIG. Since there is nothing to constrain each other, the first block 11 (female threaded portion 112) and the second block 12 expand evenly according to their respective coefficients of thermal expansion, rather than the bolt 13 (male threaded portion 131). Extends greatly in the axial direction. As a result, due to the difference in the coefficient of thermal expansion, the male screw portion 131 receives the same axial force F1 as in FIGS. 6, 8 and 10 as the axial force stretched in the axial direction as in FIG. ..

In the actual embodiment, the tightening load for "preventing leakage of the rubber or resin as the raw material to be injected" is applied when assembling the mold shown in FIG. At room temperature, the screwing range of the male threaded portion 131 and the female threaded portion 112 is the thread of each thread (the first thread m1 to the ninth thread m9 of the thread of the male threaded portion 131 and the thread of the female threaded portion 112. 1st mountain f1 to 9th mountain f9) are evenly screwed together. That is, the axial force F _T caused by tightening at torque set bolt 13 at normal temperature state, acts evenly to each of the first crest m1 of the thread of the male threaded portion 131 to the ninth crest m9 and the axial force to the individual threads, the axial force of the 1/9 of the axial force F _T is applied. However, the axial force F _T by fastening load applied during assembly in the normal temperature is very small compared to the axial force F1 due to the difference in thermal expansion coefficient in a state of being heated to the heating temperature.

Further, the bolt 13 also receives the axial force F2 in the pressure rise due to thermal expansion of the material of the rubber or resin, this F2 is less than F _T by tightening torque.

As a result, as shown in FIG. 12, the threads of the male threaded portion 131 and the female threaded portion 112 are in contact with each other at the ninth thread f9 of the thread of the female threaded portion 112 and the male threaded portion 131. because only 9 mountain m9 of threads, the axial force of the first block 11 and the axial force F1 and axial force F2 and fastening load of a pressure rise, which is the sum of the thermal extension amount of the second block 12 F _T All (F1 + F2 + _FT ) are the axial forces that generate a shear load on this one peak.

In the case of the present embodiment, in addition to the state shown in FIG. 12, a plurality of disc springs (two in the present embodiment) as elastic members 14 between the head 133 of the bolt 13 and the edge of the bolt hole 121 of the second block 12. ) Is installed. When the first block 11 and the second block 12 are expanded by the heat treatment, the elastic member 14 has a female screw portion 112 due to a load acting on the bolt 13 equal to or more than the tightening load and a tensile load acting in the tightening direction. Shrinks to stay below the shear load at which it breaks. That is, when the elastic member 14 contracts, the ninth thread f9 of the thread of the female thread 112 that is engaged with the ninth thread m9 of the thread of the male thread 131 is prevented from being broken by shear stress. ..

Hereinafter, the molding dies 1 of the second to fifth embodiments will be described with reference to the drawings. In each embodiment, the configurations having the same functions as the configuration of the molding die 1 of the first embodiment are designated by the same reference numerals, and the detailed description thereof will be described in the corresponding description in the first embodiment. I will take this into consideration.

In summary, the contact portion of the head 133 of the bolt 13 having a small coefficient of thermal expansion with the block 12 and the contact portion of the ninth thread m9 of the male threaded portion 131 with the ninth thread f9 are the contact portions of the second block 12. It becomes the abutment ninth mountain f9 abutment portion and the female screw portion 112 in a state where tightening in the axial force of F1 + F2 + F _T, the plastic deformation from the ninth mountain f9 of weakest female screw portion 112, destruction begins.

<Second embodiment>
The molding die 1 of the second embodiment according to the present invention will be described with reference to FIGS. 13 to 15. FIG. 13 is a plan view of the molding die 1 as viewed from above, and FIG. 14 is a cross-sectional view of the molding die 1 along the line F14-F14 in FIG. 13, showing the first block 11 and the first block 11. It is sectional drawing which cut in the plane passing through the bolt connecting the block 16 of 3, the bolt connecting the second block 12 and the third block 16, and the inlet nozzle 31 and the outlet nozzle 32 for injecting the raw material into the cavity 2. .. Further, FIG. 15 is a cross-sectional view of the molding die 1 along the line F15-F15 in FIG. 13, which is a cross-sectional view taken along a plane passing through a bolt 13 arranged on one side around the cavity 2.

The molding die 1 of the second embodiment has three blocks (11 in the first block, 12 in the second block, and 16 in the third block) in the first direction as shown in FIGS. 14 and 15. It is configured by overlapping. As shown in FIG. 14, the first block 11, the second block 12, and the third block 16 have recesses 21, 22, and 23 that form a continuous cavity 2. As shown in FIG. 13, bolts 13 for connecting adjacent blocks are arranged around the cavity 2.

In the case of the present embodiment, as shown in FIGS. 14 and 15, the first block 11 is arranged at the lower part and the second block 12 is arranged at the upper part. The third block 16 is a block arranged between the first block 11 and the second block 12, and is provided with both a bolt hole 121 and a female screw hole 111. The bolt 13 is arranged so as to individually connect the first block 11 and the third block 16 and the second block 12 and the third block 16 which are adjacent blocks to each other.

Further, in adjacent blocks, the bolt hole 121 of one block and the female screw hole 111 of the other block, in the present embodiment, the female screw hole 111 of the first block 11 and the bolt hole 121 of the third block 16, and , The female screw hole 111 of the third block 16 and the bolt hole 121 of the second block 12 are arranged at positions overlapping each other in the first direction. Further, the female screw hole 111 and the bolt hole 121 provided in the third block 16 arranged in the middle are arranged at positions that do not overlap in the first direction.

In the present embodiment, as shown in FIGS. 13 and 15, a bolt 13 connecting the first block 11 and the third block 16 and a bolt 13 connecting the second block 12 and the third block 16 However, they are arranged so as to be arranged alternately. Therefore, the bolt 13 connecting the first block 11 and the third block 16 is attached before the second block 12 is superposed on the third block 16, and the blocks are held together with a predetermined tightening torque. connect.

Further, as shown in FIGS. 14 and 15, at least the disc spring of the elastic member 14 is attached to the edge of the bolt hole 121 provided in the third block 16 arranged in the middle facing the second block 12 side. A seating portion 122 having a size for accommodating the head 133 of the bolt 13 is provided. In the second embodiment, not only the bolt hole 121 of the third block 16 but also the bolt hole 121 of the second block 12 has a counterbore portion of the same size as the counterbore portion 122 of the third block 16. 122 is provided.

In the molded mold 1 configured as described above, the material of each block (first block 11, second block 12, third block 16) is an aluminum alloy having excellent thermal conductivity and light weight. In particular, 7000 series Al-Zn-Mg based alloy, which is a high-strength aluminum alloy in Japanese Industrial Standards, specifically, A7075-T6 material of Japanese Industrial Standards "JIS H 4000: 2014 Aluminum and Aluminum Alloy Plates and Stripes". It is made of so-called "super duralumin". Further, the material of the bolt 13 has a smaller coefficient of thermal expansion than each block (11, 12, 13) and is a high-strength material, for example, chrome molybdenum steel used for general bolts, specifically, Japanese Industrial Standards. SCM435 of the standard "JIS G 4105 chrome molybdenum steel material" is adopted in this embodiment. As another material, for example, it may be manufactured from S45C of a general carbon steel material for machine structure (JIS G 4051). All are manufactured in accordance with Japanese Industrial Standards "JIS B 1051: 2000 Mechanical Properties of Carbon Steel and Alloy Structure Fastening Parts-Part 1: Bolts, Screws and Implantable Bolts".

Even if the thermal expansion coefficient of the block (11, 12, 13) is larger than the thermal expansion coefficient of the material of the bolt 13 of the fastening member, the elastic member 14 is held between the head 133 of the bolt 13 and the bolt hole 121. Therefore, as in the first embodiment, the female screw in the screwed portion of the male screw portion 131 of the bolt 13 and the female screw portion 112 of the female screw hole 111 due to the difference in thermal expansion when the molding die 1 is heat-treated. It is possible to reduce the application of excessive shear stress to the threads on the inner side (tip side of the bolt 13) of the hole 111. As a result, the service life of the molding die 1 that repeats assembly, heat treatment, and disassembly can be extended.

<Third embodiment>
The molding die 1 of the third embodiment according to the present invention will be described with reference to FIG. FIG. 16 is a view corresponding to FIG. 15 of the second embodiment, and is a cross-sectional view taken along a plane passing through the center of a bolt 13 arranged along one side around the cavity 2.

The molding die 1 of the third embodiment has four blocks (one for the first block 11, one for the second block 12, and two for the third block 16) as a plurality of blocks. The blocks are overlapped in the direction of the above, and adjacent blocks are connected by bolts 13. In the present embodiment, the first block 11, the third block 16, the third block 16, and the third block and the second block are connected by bolts in this order from the bottom. In any of the connecting portions, the female screw hole 111 of one block and the bolt hole 121 of the other block that can be placed through the adjacent blocks are arranged at positions overlapping in the first direction, and the third is arranged in the middle. The female screw hole 111 and the bolt hole 121 provided in the block 16 are arranged at positions that do not overlap each other in the first direction.

The molding die 1 of the third embodiment has a plurality of the third blocks 16 of the second embodiment, and is connected by the bolt 13 and the elastic member 14, respectively, so that the molding die 1 is heated by the heat treatment. Even if an expansion difference occurs, it is possible to reduce the application of excessive shear stress to the screwed portion. Therefore, as in the other embodiments, the service life of the molding die 1 that repeats assembly, heat treatment, and disassembly can be extended. Further, in the molding die 1 of the third embodiment, the cavity 2 can be expanded in the first direction by further adding the third block 16.

<Fourth Embodiment>
The molding die 1 of the fourth embodiment according to the present invention will be described with reference to FIG. FIG. 17 is a view corresponding to FIG. 15 of the second embodiment and FIG. 16 of the third embodiment, and is cut along a plane passing through the center of the bolt 13 arranged along one side around the cavity 2. It is a sectional view.

The molding die 1 of the fourth embodiment is configured by superimposing three blocks (one first block 11 and two second blocks 12) as a plurality of blocks in the first direction. Adjacent blocks are connected by bolts 13. In the present embodiment, the first block 11 is sandwiched in the center in the first direction as one block between adjacent blocks, and the second block 12 is arranged on both sides of the first block 11 as the other block. Therefore, the first block 11 has female screw holes 111 which are open to the second block 12 side and have a female screw portion 112 formed on both sides. The female screw holes 111 of the first block 11 are arranged at positions that do not overlap each other in the first direction.

Since the first block 11 is arranged in the center of the molding die 1 of the fourth embodiment, it is suitable when the first block 11 is desired to be enlarged in the first direction. The female screw hole 111 of the first block 11 has a first direction when the female screw portion 112 can secure a sufficient screwing length for the male screw portion 131 of the bolt 13 mounted from both sides. It may be arranged at a position overlapping the above, or may communicate with each other.

<Fifth Embodiment>
The molding die 1 of the fifth embodiment according to the present invention will be described with reference to FIG. FIG. 18 is a view corresponding to FIG. 15 of the second embodiment, FIG. 16 of the third embodiment, and FIG. 17 of the fourth embodiment, and bolts arranged along one side around the cavity 2. 13 is a cross-sectional view cut along a plane passing through the center of 13.

The molding die 1 of the fifth embodiment has four blocks (one first block 11, two second blocks 12, and one third block 16) as a plurality of blocks. The blocks are overlapped in the direction of the above, and adjacent blocks are connected by bolts 13. The first block 11 has female screw holes 111 on both sides facing the adjacent blocks, as in the case of the fourth embodiment. Then, in FIG. 18, a second block 12 is joined to the lower part of the first block 11, and a third block 16 is joined to the upper part. A second block 12 is joined to the upper part of the third block 16.

The molding dies 1 of the fifth embodiment configured as described above have the functions and effects of the molding dies 1 of the first embodiment, as well as the molding dies 1 and 4 of the third embodiment. It has both functions and effects of the molding die 1 of the embodiment.

The molding die 1 according to the present invention has been described above using the first to fifth embodiments. According to these embodiments, a material having excellent thermal conductivity can be used as a block material as a mold for heat treatment, and a bolt made of a generally used high-strength material can be used as a bolt for molding. it can.

By providing the elastic member 14 between the second block 12 and the bolt 13, the difference in thermal expansion in the heat treatment is maintained while maintaining the tightening force required for mold clamping when the material is injected into the cavity 2. It is possible to absorb the excessive load that accompanies. In particular, by adopting a disc spring as the elastic member 14, the space required for accommodating the elastic member 14 can be reduced, and the outer shape of the molding die 1 can also be reduced. Further, by using a plurality of disc springs as the elastic member 14, the spring load and the effective height can be easily changed. Further, the load can be evenly applied in the circumferential direction with respect to the axis of the bolt 13.

The first to fifth embodiments described above are merely examples for facilitating understanding in carrying out the present invention. Therefore, in carrying out the present invention, it is possible to replace each configuration with one having the same function without departing from the spirit thereof, and these are also included in the present invention. It is also included in the present invention that some of the configurations described in each embodiment are combined or replaced with each other.

1 ... Molded mold, 2 ... Cavity, 11 ... 1st block, 12 ... 2nd block, 13 ... Bolt, 14 ... Elastic member, 15 ... Retaining ring, 111 ... Female screw hole, 112 ... Female screw part, 121 ... Bolt hole, 122 ... Seating ring, 131 ... Male screw part, 132 ... Body, 133 ... Head, 16 ... Third block, F ... Axial force.

Claims (10)

A molding die composed of at least two blocks, in which adjacent blocks are connected by bolts having a free length of 100 mm or more .
One of the adjacent blocks has a female screw hole that opens to the other block side and has a female screw portion formed therein.
The other adjacent blocks have bolt holes that are open to the one block side.
The bolt has a smaller coefficient of thermal expansion than the block, and in a state of being passed through the bolt hole, a male screw portion provided at the tip is screwed into the female screw portion, and the edge and head of the bolt hole. A predetermined tightening load is applied between the male screw portion and the head with the elastic member attached between the and.
When the block expands due to heat treatment, the elastic member has a shear load in which the female screw portion is destroyed by a tensile load acting on the bolt when the load acting on the bolt is equal to or greater than the tightening load and acting in the tightening direction of the bolt. A molded mold characterized by shrinking to be maintained below. The other block has a counterbore portion for accommodating the elastic member at the edge of the bolt hole on the opposite side of the one block.
The molding die according to claim 1, further comprising a retaining ring that is fitted to the inner peripheral surface of the seated portion and holds the elastic member in the seated portion. The molded mold according to claim 2, wherein the seating portion has a size for accommodating the elastic member and the head. The length of the male-threaded portion and the female-threaded portion screwed together is 0.8D or more and 1.6D or less when the nominal diameter of the female-threaded portion is D. The described molding mold. The elastic member includes a plurality of disc springs, and when the nominal diameter of the female screw portion is D, the elastic member has a shrinkage allowance of 0.005D or more in a dimension of 0.5D or less in the tightening direction of the bolt. The molding die according to claim 1 or 2, wherein the molding die is characterized by the above. The molded mold according to any one of claims 1 to 5, wherein the elastic member is composed of at least one disc spring. The molding die according to claim 6, wherein the elastic member is composed of a plurality of disc springs. The molding die according to claim 1, wherein the bolt has a free length set to 5 times or more a nominal diameter of the bolt. The molding die according to claim 1, wherein the bolt has a free length set to 8 times or more a nominal diameter of the bolt. The molding die according to claim 1, wherein the bolt has a free length set to 8.4 times or more the nominal diameter of the bolt.

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