Injection molding machine

Abstract

To provide an injection molding machine that can suppress fluctuations in the gap between the inner and outer rings of a bearing. [Solution] An injection molding machine comprising: a holding member for holding a second mold which forms a cavity space together with a first mold; a rotating shaft which is positioned to protrude from the side of the holding member opposite to the side that holds the second mold, and to which the rotational force of the holding member is transmitted or to which rotational force is transmitted to the holding member; and a support member which rotatably supports the holding member via a bearing into which the rotating shaft is fitted, wherein the holding member and the rotating shaft are positioned such that a first surface of the holding member which faces the rotating shaft and a second surface of the rotating shaft which faces the holding member are in contact, and a recess is formed in the rotating shaft which forms a gap between the second surface and the recessed first surface, or a recess is formed in the holding member which forms a gap between the first surface and the recessed second surface.

Description

Technical Field

[0001] The present invention relates to an injection molding machine.

Background Art

[0002] Patent Document 1 describes an injection molding machine configured as described below. That is, the injection molding machine includes a mold clamping device that opens and closes a mold device, a first ejector device that ejects a first unnecessary product formed by the mold device, a second ejector device that ejects both a second molded product and a second unnecessary product formed by the mold device, a first injection device that injects a molding material into the mold device, a second injection device that injects a molding material into the mold device, a first moving device that moves the first injection device forward and backward with respect to the mold device, a second moving device that moves the second injection device forward and backward with respect to the mold device, a control device that controls each component of the injection molding machine, and a frame that supports each component of the injection molding machine. The mold clamping device performs mold closing, pressure boosting, mold clamping, pressure release, and mold opening of the mold device. The mold device includes a fixed mold and a movable mold. Further, the mold clamping device includes a fixed platen, a movable platen that is movably arranged in the mold opening and closing direction with respect to the mold clamping device frame, a rotary table that is rotatably supported by the movable platen via a slide plate, a rotation mechanism that rotates the rotary table, and a movement mechanism that moves the movable platen forward and backward with respect to the fixed platen. The fixed platen is fixed to the mold clamping device frame. A fixed mold is attached to the opposing surface of the fixed platen with respect to the movable platen. The movable platen is positioned to move freely in the mold opening and closing direction relative to the mold clamping device frame. A movable mold is attached to the surface of the movable platen facing the fixed platen via a rotary table. The movable platen has a front plate that rotatably supports the rotary table via a slide plate, an intermediate block positioned radially inward of the cylindrical portion of the rotary table, a gear restraint block positioned outside the intermediate block when viewed in the mold opening and closing direction, a rear block provided behind the intermediate block, and a toggle link mounting portion provided on the rear end surface of the rear block. The movable platen rotatably supports the rotation axis of the rotary table via bearings. The rotary table is rotatably mounted to the movable platen via a sliding plate. The rotational centerline of the rotary table is parallel to the mold opening and closing direction. The rotation mechanism rotates the rotary table. The rotation mechanism includes a rotary motor and a transmission mechanism that transmits the rotational driving force of the rotary motor to the rotary table. In the injection molding machine configured as described above, during mold clamping, the first movable molding surface of the movable mold and the first fixed molding surface of the fixed mold form a first cavity space, while the second movable molding surface of the movable mold and the second fixed molding surface of the fixed mold form a second cavity space. Molding material is supplied to the first cavity space from the first injection device, and the first molded product is formed. Subsequently, mold opening is performed. Next, the first ejector device ejects the first unwanted material from the movable mold. The first unwanted material, along with the first molded product, solidifies inside the mold device. Then, the rotating mechanism rotates the rotary table by 180°. The movable mold rotates by 180° in conjunction with the rotation of the rotary table. At this time, the first molded product rotates 180° together with the movable mold without being ejected. After that, mold clamping is performed. During mold clamping, the second movable molding surface and the first fixed molding surface form a first cavity space, and the first movable molding surface and the second fixed molding surface form a second cavity space. As described above, the first molded product is placed in a portion of the second cavity space. Molding material is supplied from the second injection device to the remaining portion of the second cavity space, and the second molded product is molded. The first molded product is molded in parallel with the molding of the second molded product. The first molded product is molded in the first cavity space. Subsequently, the mold is opened. Next, the second ejector device ejects both the second molded product and the second waste from the movable mold. The second waste solidifies inside the mold device along with the second molded product. After being ejected from the movable mold, the second waste is separated from the second molded product. The first waste is ejected in parallel with the ejection of both the second molded product and the second waste. After that, the mold is opened and the rotary table is rotated 180° again. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-84411 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, there has been an increasing demand for injection molding machines capable of molding products using thermosetting resins as molding materials. When thermosetting resins are used as molding materials, the temperature of the cavity space becomes high, which increases the temperature transmitted to the holding member that holds the movable mold (a rotary table in Patent Document 1) and the rotating shaft. When the temperature transmitted to the rotating shaft becomes high, the temperature of the inner ring of the bearing also becomes high, so the amount of thermal expansion of the rotating shaft and the inner ring of the bearing becomes larger relative to the amount of thermal expansion of the outer ring of the bearing, and the gap between the inner and outer rings of the bearing becomes smaller. And when the gap between the inner and outer rings of the bearing becomes smaller, the load on the rotary motor that rotates the holding member that holds the movable mold increases. On the other hand, for example, when molding is started while the material is cold, the gap between the inner and outer rings of the bearing increases due to shrinkage. When the gap between the inner and outer rings of the bearing increases, the rotational accuracy of the retaining member and the movable mold deteriorates. Thus, fluctuations in the gap between the inner and outer rings of a bearing can cause fluctuations in the load on the rotating motor and deterioration in the rotational accuracy of the retaining member or movable mold. Therefore, it is desirable to suppress fluctuations in the gap between the inner and outer rings of a bearing. The present invention aims to provide an injection molding machine that can suppress fluctuations in the gap between the inner and outer rings of a bearing. [Means for solving the problem]

[0005] The present invention, completed with this objective in mind, is an injection molding machine comprising: a holding member for holding a second mold which together with a first mold forms a cavity space; a rotating shaft which is arranged to protrude from the side of the holding member opposite to the side that holds the second mold, and to which the rotational force of the holding member is transmitted or to which rotational force is transmitted to the holding member; and a support member which rotatably supports the holding member via a bearing into which the rotating shaft is fitted, wherein the holding member and the rotating shaft are arranged so that a first surface of the holding member which faces the rotating shaft and a second surface of the rotating shaft which faces the holding member are in contact, and a recess is formed in the rotating shaft which is recessed from the second surface and forms a gap between it and the first surface, or a recess is formed in the holding member which is recessed from the first surface and forms a gap between it and the second surface. Here, the rotating shaft may have a through hole formed in the center in the direction of the rotational centerline, and a recess formed in the second surface extending from the through hole to the outer circumference. Furthermore, the recesses may be formed in multiple locations radiating from the through-hole. Furthermore, the rotating shaft may have multiple female threads formed on its second surface, into which the male threads of a fastening member used for connecting with the holding member are tightened, and the recesses may be formed between the multiple female threads. Furthermore, the rotating shaft may have a through hole formed in the center in the direction of the rotational centerline, and the holding member may have multiple recesses formed in the first surface that extend radially from the center. Furthermore, the rotating shaft may be provided with fins that protrude inward from the inner surface of the through hole. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an injection molding machine that can suppress fluctuations in the gap between the inner and outer rings of a bearing. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a schematic configuration of an injection molding machine according to the first embodiment. [Figure 2] This figure shows an example of a cross-section of a movable platen, a rotary table, etc. [Figure 3] This is an example of a perspective view of the rotation axis according to the first embodiment, viewed from the front. [Figure 4] This is an example of a diagram showing the rotary table according to the second embodiment, viewed from the rear towards the centerline. [Figure 5] This is an example of a diagram showing the rotation axis according to the third embodiment, viewed from the front towards the centerline. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below with reference to the attached drawings. <First Embodiment> Figure 1 is a diagram showing an example of the schematic configuration of an injection molding machine 1 according to the first embodiment. In the following description, the front side of Figure 1 may be simply referred to as the "front side," and the back side of Figure 1 may be simply referred to as the "back side." Figure 2 shows an example of a cross-section of the movable platen 120, the rotary table 520, etc. The injection molding machine 1 comprises a mold device 80, a clamping device 100, a first ejector device 201, a second ejector device (not shown), a first injection device 301, and a second injection device (not shown). The injection molding machine 1 also comprises a frame 400, a first moving device 401 for moving the first injection device 301 relative to the mold device 80, a second moving device (not shown) for moving the second injection device relative to the mold device 80, and a control device 500. The first ejector device 201, the first injection device 301, and the first moving device 401 are located on the front side, while the second ejector device, the second injection device, and the second moving device are located on the rear side. Furthermore, in the vertical direction of Figure 1, the positions of the first ejector device 201 and the second ejector device, the positions of the first injection device 301 and the second injection device, and the positions of the first moving device 401 and the second moving device overlap. For this reason, the second ejector device, the second injection device, and the second moving device are not shown in Figure 1.

[0009] (Mold device 80) The mold apparatus 80 includes a fixed mold 81 and a movable mold 82. The fixed mold 81 and the movable mold 82 can be exemplified as rectangular parallelepipeds. The fixed mold 81 has a first fixed molding surface 811 and a second fixed molding surface (not shown). The movable mold 82 has a first movable molding surface 821 and a second movable molding surface (not shown). Figure 1 shows the fixed mold 81 and the movable mold 82 in the open state. When the fixed mold 81 and the movable mold 82 are closed, a cavity space is formed between the fixed mold 81 and the movable mold 82.

[0010] (mold clamping device 100) The mold clamping device 100 includes a fixed platen 110, a movable platen 120, a toggle support 130, tie bars 140, a toggle mechanism 150, a mold clamping motor 160, and a ball screw 170. The mold clamping device 100 further includes a rotary table 520 supported rotatably with respect to the fixed platen 110 by the movable platen 120, and a rotation mechanism 530 for rotating the rotary table 520. The mold clamping device 100 also includes a rotating shaft 570 attached to the rotary table 520, and a bearing 580 that rotatably supports the rotary table 520 and the rotating shaft 570.

[0011] The fixed platen 110 is fixed to the frame 400. A fixed mold 81 is attached to the opposing surface of the fixed platen 110 with respect to the movable platen 120 such that the first fixed molding surface 811 is on the front side and the second fixed molding surface is on the back side.

[0012] The movable platen 120 is provided movably in the left - right direction of FIG. 1 with respect to the frame 400. A movable mold 82 is attached to the opposing surface of the movable platen 120 with respect to the fixed platen 110. By moving the movable platen 120 in the left - right direction of FIG. 1 with respect to the fixed platen 110, mold closing, pressure boosting, mold clamping, pressure releasing, and mold opening of the mold device 80 are performed. In the mold clamping device 100, the left - right direction of FIG. 1 is referred to as the "mold opening - closing direction", the moving direction of the movable platen 120 at the time of mold closing (the right direction of FIG. 1) is referred to as "front", and the moving direction of the movable platen 120 at the time of mold opening (the left direction of FIG. 1) may be referred to as "rear". The configuration of the movable platen 120 will be described in detail later.

[0013] The toggle support 130 is provided movably in the mold opening - closing direction on the frame 400. The tie bars 140 connect the fixed platen 110 and the toggle support 130 with a predetermined interval in the mold opening - closing direction. It can be exemplified that a plurality of tie bars 140 (for example, four) are provided.

[0014] The toggle mechanism 150 is positioned between the movable platen 120 and the toggle support 130. The toggle mechanism 150 moves the movable platen 120 relative to the toggle support 130 in the mold opening and closing direction. The toggle mechanism 150 has a crosshead 151 and a pair of link groups 152. The crosshead 151 has a nut for a ball screw 170. When the ball screw 170 rotates around its axis, the crosshead 151 moves relative to the toggle support 130 in the mold opening and closing direction. This causes the link group 152 to flex and extend, moving the movable platen 120 relative to the toggle support 130 in the mold opening and closing direction.

[0015] The clamping motor 160 and ball screw 170 are mounted on the toggle support 130 and operate the toggle mechanism 150. The ball screw 170 rotates around its axis in response to the rotational drive of the clamping motor 160, moving the crosshead 151, which has a nut, relative to the toggle support 130 in the mold opening and closing direction.

[0016] The movable platen 120, rotary table 520, rotation mechanism 530, rotation shaft 570, etc. will be described below. (Movable platen 120) The movable platen 120 includes a front plate 121 located at the very front, an intermediate block 124, and a gear restraint block 125 positioned outside the intermediate block 124. The movable platen 120 also includes a rear block 126 located behind the intermediate block 124, and a toggle link mounting portion 128 located on the rear end face of the rear block 126. The movable platen 120 may be made of, for example, cast iron. The front plate 121, the intermediate block 124, the rear block 126, and the toggle link mounting portion 128 may be separate parts or may be integrally formed by casting or other means.

[0017] A first rod hole 122 is formed in the front plate 121, penetrating the front plate 121 in the mold opening and closing direction. A first ejector rod 211 is positioned in the first rod hole 122 so as to be movable in the mold opening and closing direction. A second rod hole (not shown) is also formed in the front plate 121, penetrating the front plate 121 in the mold opening and closing direction. A second ejector rod (not shown) is positioned in the second rod hole (not shown) so as to be movable in the mold opening and closing direction.

[0018] The intermediate block 124 is positioned inside the cylindrical portion 524 of the rotary table 520, which will be described later. The intermediate block 124 can be exemplified as being cylindrical in shape, for example, with the column direction being the direction of the centerline. Inside the intermediate block 124, a space is formed for the placement of the first ejector device 201 and a space for the placement of the second ejector device (not shown).

[0019] A front plate 121 is attached to the front end surface of the intermediate block 124. The front plate 121 and the intermediate block 124 have fitting recesses 127 into which bearings 580 are fitted. Slide plates 610 are provided on the front end surface of the front plate 121, both on the side in front of the fitting recess 127 and on the side behind the fitting recess 127. The slide plates 610 are, for example, rectangular parallelepipeds and are fixed to the front plate 121 using, for example, bolts (not shown). The material of the slide plates 610 can be exemplified as being softer than the disc portion 523 of the rotary table 520, which will be described later, for example, copper or a copper alloy such as brass.

[0020] The gear restraint block 125 is positioned in front of the rear block 126 and outside the intermediate block 124. The gear restraint block 125 restrains the forward movement of the passive gear 535 of the rotating mechanism 530 (described later) via the slide plate 620. The gear restraint block 125 suppresses the tilting of the rotary table 520.

[0021] The rear block 126 is located behind the intermediate block 124 and is supported by the platen carriage 190. The rear block 126 can be exemplified as, for example, a rectangular parallelepiped. Inside the rear block 126, there is a space for arranging the first ejector device 201 and a space for arranging the second ejector device. The intermediate block 124 is attached to the front end face of the rear block 126.

[0022] The toggle link mounting portion 128 is provided so as to protrude rearward from the rear end surface of the rear block 126. The toggle link mounting portion 128 is provided at both the upper and lower ends of the rear block 126. The toggle link mounting portion 128 has a plurality of toggle link mounting plates spaced horizontally, with the plate thickness direction facing the horizontal direction. Each of the plurality of toggle link mounting plates has a pin hole 129 at its tip. A pin is inserted through the pin hole 129, and the link of the toggle mechanism 150 is pivotably attached to the toggle link mounting portion 128 via the pin.

[0023] (Rotating table 520) The rotary table 520 is rotatably supported relative to the movable platen 120 via a slide plate 610. The direction of the rotational centerline CL of the rotary table 520 is the same as the mold opening and closing direction, and the position of the rotational centerline CL is between the first movable molding surface 821 and the second movable molding surface (not shown) of the movable mold 82. In the following description, the mold opening and closing direction may be referred to as the "centerline direction." Also, the side of the rotary table 520 that is on the rotational centerline CL side may be referred to as the "inside," and the side that is away from the rotational centerline CL may be referred to as the "outside."

[0024] The rotary table 520 has a mold mounting section 521 to which the movable mold 82 is attached, and a winding section 522 to which the flexible holder 510 is wound. The rotary table 520 is installed inside the tie bars 140 so as not to interfere with the tie bars 140.

[0025] The mold mounting portion 521 is plate-shaped and perpendicular to the centerline direction, and can be exemplified by being rectangular parallelepiped-shaped. The winding section 522 has a disc-shaped disc portion 523 to which the mold mounting section 521 is fixed, and a cylindrical portion 524 that extends rearward from the outer circumference of the disc portion 523. The rotary table 520 may, for example, be made of cast iron. The mold mounting portion 521, the disc portion 523, and the cylindrical portion 524 may be separate parts, or they may be integrally formed by casting or other means.

[0026] The cylindrical portion 524 has a circumferential surface 525. A passive gear 535 of the rotating mechanism 530, described later, is fixed to the circumferential surface 525 over its entire circumference. A flexible holder 510 is also wound around the circumferential surface 525. The flexible holder 510 has one end fixed to the rotary table 520 and the other end fixed to the movable platen 120. Examples of flexible holders 510 include cable carriers (registered trademark).

[0027] (Rotation mechanism 530) The rotating mechanism 530 includes a rotating motor 531 and a transmission mechanism 532 that transmits the rotational driving force of the rotating motor 531 to the rotating table 520. The transmission mechanism 532 is composed of, for example, a drive gear 533, an intermediate gear 534, and a passive gear 535.

[0028] The rotating mechanism 530 rotates the rotary table 520 by a first rotation angle and a second rotation angle. The first rotation angle is the angle of rotation that forms a cavity space between the first movable molding surface 821 of the movable mold 82 and the first fixed molding surface 811 of the fixed mold 81. The first rotation angle is, for example, 0°. On the other hand, the second rotation angle is the angle of rotation that forms a cavity space between the second movable molding surface (not shown) of the movable mold 82 and the first fixed molding surface 811 of the fixed mold 81. The second rotation angle is, for example, 180°.

[0029] In this embodiment, the rotation mechanism 530 reverses the direction in which the rotary table 520 rotates from the first rotation angle to the second rotation angle, and the direction in which it rotates from the second rotation angle to the first rotation angle. This returns the arrangement of the wiring and piping fixed to the rotary table 520 to its original position, making it easier to route the wiring and piping.

[0030] (Rotation axis 570) The rotating shaft 570 is a cylindrical member. The rotating shaft 570 and the rotary table 520 are connected by multiple bolts 550 (four in this embodiment). The rotating shaft 570 is fitted into a bearing 580 attached to the movable platen 120, so that the rotating shaft 570 and the rotary table 520 can rotate integrally with the movable platen 120 via the bearing 580. Details of the rotating shaft 570 and the connection points between the rotating shaft 570 and the rotary table 520 will be described in detail later.

[0031] The mold clamping device 100, configured as described above, performs mold closing, pressure boosting, mold clamping, depressurization, and mold opening processes under the control of the control device 500. In the mold closing process, the clamping device 100 drives the clamping motor 160 to rotate the ball screw 170, moving the crosshead 151 forward at a set speed to the mold closing completion position. As a result, the movable platen 120 moves forward, and the movable mold 82 comes into contact with the fixed mold 81. In the pressure boosting process, the clamping device 100 further drives the clamping motor 160 to advance the crosshead 151 from the closed position to the clamping position. This generates a clamping force in the mold device 80.

[0032] In the clamping process, the clamping device 100 drives the clamping motor 160 to maintain the position of the crosshead 151 in the clamping position. This maintains the clamping force generated in the pressurization process during the clamping process. In the clamping process, for example, when the rotary table 520 is rotated to a first rotation angle, the first injection device 301 fills the cavity space formed between the first movable molding surface 821 of the movable mold 82 and the first fixed molding surface 811 of the fixed mold 81 with liquid first molding material. The filled first molding material solidifies to obtain a first molded product. Meanwhile, the second injection device fills the cavity space formed between the first molded product molded on the second movable molding surface of the movable mold 82 and the second fixed molding surface of the fixed mold 81 with liquid second molding material. The filled second molding material solidifies to obtain a second molded product containing the first molded product.

[0033] In the clamping process, for example, when the rotary table 520 is rotated to the second rotation angle, the first injection device 301 fills the cavity space formed between the second movable molding surface of the movable mold 82 and the first fixed molding surface 811 of the fixed mold 81 with liquid first molding material. The filled first molding material solidifies to obtain the first molded product. Meanwhile, the second injection device fills the cavity space formed between the first molded product molded on the first movable molding surface 821 of the movable mold 82 and the second fixed molding surface of the fixed mold 81 with liquid second molding material. The filled second molding material solidifies to obtain the second molded product, which includes the first molded product.

[0034] In the depressurization process, the clamping device 100 drives the clamping motor 160 to rotate the ball screw 170 in the opposite direction to that of the mold closing and pressure boosting processes, causing the crosshead 151 to retract from the clamping position to the mold opening start position. This causes the movable platen 120 to retract, reducing the clamping force. The mold opening start position can be exemplified as being the same position as the mold closing completion position described in the mold closing and pressure boosting processes. In the mold opening process, the mold clamping device 100 drives the mold clamping motor 160 to retract the crosshead 151 from the mold opening start position to the mold opening completion position at a set movement speed. As a result, the movable platen 120 retracts, and the movable mold 82 is separated from the fixed mold 81.

[0035] (First ejector device 201, etc.) The first ejector device 201 performs the ejection process under the control of the control device 500. The second ejector device has the same configuration as the first ejector device 201 and also performs the ejection process under the control of the control device 500. The first ejector device 201 and the second ejector device are attached to the movable platen 120 and move together with the movable platen 120 in the mold opening and closing direction. In the ejection process, the first ejector device 201 operates a movable member provided on the movable mold 82 to eject and detach the unwanted product from the movable mold 82. Then, the second ejector device operates a movable member provided on the movable mold 82 to eject and detach the unwanted product and the second molded product from the movable mold 82.

[0036] (Rotation axis 570, rotary table 520) Figure 3 is an example of a perspective view of the rotation axis 570 as seen from the front according to the first embodiment. Figure 2 shows an example of a cross-section when the movable platen 120, rotary table 520, and rotary shaft 570 are cut by a plane passing through the rotation centerline CL and parallel to the vertical direction. In Figure 2, the upper half of the cross-section of the rotary shaft 570 is the part where the female thread 574, described later, is formed, and the lower half is the part where the recess 575, described later, is formed. The details of the rotating shaft 570 and the connection point between the rotating shaft 570 and the rotating table 520 will be explained below with reference to Figures 2 and 3.

[0037] The rotating shaft 570 has two cylindrical parts of different diameters: a base end 571 positioned on the disc portion 523 side (in other words, the front side) of the rotary table 520, and a shaft portion 572 positioned on the opposite side of the base end 571 from the disc portion 523 (in other words, the rear side). The centerlines of the base end 571 and the shaft portion 572 coincide, and the outer diameter of the base end 571 is larger than the outer diameter of the shaft portion 572. The rotating shaft 570 is fitted with the shaft portion 572 inside the inner ring of a bearing 580 attached to the movable platen 120, and the base end 571 is positioned on the disc portion 523 side of the inner ring of the bearing 580. Therefore, the centerline of the shaft portion 572 coincides with the rotation centerline CL described above.

[0038] The rotating shaft 570 has a through hole 573 formed in the center in the direction of the centerline. Furthermore, the rotating shaft 570 has a female thread 574 formed on its front surface 576, which is the surface facing the disc portion 523, into which the male thread of the bolt 550 is tightened. Multiple female threads 574 (four in this embodiment) are formed at equal intervals around the through hole 573 (in other words, around the rotation center line CL). Furthermore, the rotating shaft 570 has recesses 575 that are recessed from the front surface 576. The recesses 575 are formed in a straight line extending from the through hole 573 to the outer circumference. In addition, multiple recesses 575 (four in this embodiment) are formed radially from the through hole 573. Each recess 575 is formed between multiple female threads 574.

[0039] The rotating shaft 570 has through holes 573 and multiple recesses 575, which divide the front surface 576 into four small faces 577. Each small face 577 has a central angle of 90°, and a chamfer 578 is applied to the point where the two sides forming the central angle intersect. As shown in Figure 3, the chamfer 578 can be exemplified as an R-chamfer. However, the chamfer 578 may also be a C-chamfer.

[0040] The disc portion 523 of the rotary table 520 has an insertion recess 527 formed in the center, into which the base end 571 of the recessed rotating shaft 570 is inserted from the rear surface 526, which is the surface facing the front plate 121 of the movable platen 120. The insertion recess 527 is cylindrical. The diameter of the insertion recess 527 is larger than the diameter of the base end 571 of the rotating shaft 570. The bottom surface 528 of the insertion recess 527 faces the front surface 576 of the rotating shaft 570.

[0041] Furthermore, the mold mounting portion 521 of the rotary table 520 has a head recess 542 formed in the center of the surface 541 to which the movable mold 82 is attached, for accommodating the head 552 of the recessed bolt 550. The head recess 542 is cylindrical, and its diameter is said to be greater than or equal to the diameter of the insertion recess 527.

[0042] Furthermore, the rotary table 520 has through-holes 543 through which the male threads of the bolts 550 pass, via insertion recesses 527 and head recesses 542. Multiple through-holes 543 (four in this embodiment) are formed at equal intervals around the rotation centerline CL to correspond to the female threads 574 of the rotating shaft 570.

[0043] The rotating shaft 570 and the rotating table 520, configured as described above, are connected by the male thread of the bolt 550 passing through the through hole 543 and tightening it onto the female thread 574 of the rotating shaft 570. When the rotating shaft 570 and the rotating table 520 are connected, the front surface 576 of the rotating shaft 570 and the bottom surface 528 of the insertion recess 527 of the rotating table 520 come into contact.

[0044] The rotating shaft 570 has its shaft portion 572 fitted inside the inner ring of the bearing 580. The bearing 580 is fitted into the movable platen 120. In the central part of the front plate 121 and intermediate block 124 of the movable platen 120, a fitting recess 127 is formed into which the bearing 580 is inserted from the front plate 121 side and into which the bearing 580 is fitted. The outer ring of the bearing 580 is press-fitted into the inner circumferential surface of the front plate 121 and intermediate block 124 that form the fitting recess 127. The bearing 580 can be a ball bearing or a roller bearing, for example.

[0045] Furthermore, the movable platen 120 has a central communication hole 126h formed in the center of the intermediate block 124 and the rear block 126, which allows the fitting recess 127 to pass through to the outside. The communication hole 126h is cylindrical, and it can be exemplified that the diameter of the communication hole 126h is smaller than the diameter of the shaft portion 572 of the rotating shaft 570.

[0046] As described above, the injection molding machine 1 includes a rotary table 520 (an example of a holding member) that holds a movable mold 82 (an example of a second mold) that forms a cavity together with a fixed mold 81 (an example of a first mold). The injection molding machine 1 also includes a rotating shaft 570 that is positioned to protrude from the side of the rotary table 520 opposite to the side that holds the movable mold 82, and to which the rotational force of the rotary table 520 is transmitted. The injection molding machine 1 also includes a movable platen 120 (an example of a support member) that rotatably supports the rotary table 520 via a bearing 580 into which the rotating shaft 570 is fitted. The rotary table 520 and the rotating shaft 570 are positioned so that the bottom surface 528 (an example of a first surface), which is the surface of the rotary table 520 facing the rotating shaft 570, and the front surface 576 (an example of a second surface), which is the surface of the rotating shaft 570 facing the rotary table 520, are in contact. Furthermore, a recess 575 is formed on the rotating shaft 570, creating a gap between the front surface 576 and the bottom surface 528 of the recessed rotating table 520.

[0047] In the injection molding machine 1 configured as described above, a recess 575 is formed on the rotating shaft 570, so the contact area with the bottom surface 528 of the rotary table 520 is smaller than in a configuration where the recess 575 is not formed (hereinafter sometimes referred to as the "comparative configuration"). In other words, in the part of the rotating shaft 570 where the recess 575 is formed, air is interposed in the recess 575 between the bottom surface 528 of the rotary table 520 and the rotating shaft 570 (in other words, the rotary table 520 and the rotating shaft 570 are not in thermal contact). As a result, in the injection molding machine 1, heat is less likely to be transferred from the rotary table 520 to the rotating shaft 570. Therefore, in the injection molding machine 1, even if the rotary table 520 becomes hot due to the filling of the cavity space formed between the fixed mold 81 and the movable mold 82 with molding material, the rotating shaft 570 is less likely to become hot.

[0048] In injection molding machine 1, the rotating shaft 570 does not easily become hot, so the inner ring of bearing 580 also does not easily become hot compared to the comparative configuration. In other words, injection molding machine 1 can reduce the heat transmitted to the inner ring of bearing 580 compared to the comparative configuration. Therefore, the amount of thermal expansion of the inner ring of bearing 580 is smaller than that of the comparative configuration, so even if the inner ring expands due to heat, the gap between the outer ring and inner ring of bearing 580 becomes larger than the gap in the comparative configuration. Thus, injection molding machine 1 can suppress fluctuations in the gap between the inner ring and outer ring of bearing 580. In addition, the rotational load (in other words, the torque of the rotating motor 531) caused by the thermal expansion of the inner ring of bearing 580 is smaller than the load in the comparative configuration.

[0049] If the thermal expansion of the inner ring of bearing 580 is large, it may be considered to set a larger gap between the inner and outer rings at room temperature to ensure a desired clearance even if the inner ring expands due to thermal expansion, thereby preventing a large load during rotation caused by thermal expansion. However, if the gap between the inner and outer rings at room temperature is set large, the gap will increase due to contraction, for example, when molding is started while cold. When the gap between the inner and outer rings of bearing 580 increases, the rotational accuracy of the rotary table 520 and the movable mold 82 deteriorates. In injection molding machine 1, the thermal expansion of the inner ring of bearing 580 is smaller than in the comparative configuration, so the gap between the inner and outer rings at room temperature can be set smaller. In other words, with injection molding machine 1, fluctuations in the gap between the inner and outer rings of bearing 580 can be suppressed even when cold. In addition, the rotational accuracy of the rotary table 520 can be stabilized when cold.

[0050] The rotating shaft 570 has a through hole 573 formed in the center in the direction of the centerline (an example of the direction of the rotation centerline), and a recess 575 is formed in the front surface 576 that extends from the through hole 573 to the outer circumference. As a result, the inside of the rotating shaft 570 and the recess 575 form a continuous space, which suppresses the temperature of the air inside the recess 575. Consequently, the heat transferred from the rotary table 520 to the rotating shaft 570 and the inner ring of the bearing 580 is reduced. Furthermore, because the recess 575 is formed to extend from the center to the outer circumference, heat is less likely to be transferred to the outer circumference of the rotating shaft 570, and the heat transferred to the inner ring of the bearing 580 is reduced. Furthermore, the movable platen 120 has a communication hole 126h formed in the central part of the intermediate block 124 and the rear block 126, which connects the fitting recess 127 to the outside. As a result, the outside of the movable platen 120 and the recess 575 of the rotating shaft 570 become a continuous space, which suppresses the temperature of the air inside the recess 575 from becoming too high. Consequently, the heat transferred from the rotary table 520 to the rotating shaft 570 and the inner ring of the bearing 580 is reduced.

[0051] Furthermore, in the injection molding machine 1, multiple recesses 575 are formed radially from the through hole 573. This ensures that the heat transmitted through the front surface 576 of the rotating shaft 570 is distributed evenly in the circumferential direction. Furthermore, the rotating shaft 570 has multiple female threads 574 formed on its front surface 576, into which the male threads of bolts 550 (an example of a fastening member) used to connect it to the rotary table 520 are tightened, and the recesses 575 are formed between the multiple female threads 574. This allows for easy connection between the rotating shaft 570 and the rotary table 520 while reducing the heat transmitted to the inner ring of the bearing 580.

[0052] In the injection molding machine 1 described above, rotational force is applied to the rotary table 520 by the rotation mechanism 530, and the rotational force of the rotary table 520 is transmitted to the rotating shaft 570. However, the machine is not limited to this configuration. For example, rotational force may be applied to the rotating shaft 570 by, for example, a motor, and the rotating shaft 570 may transmit this rotational force to the rotary table 520, causing the rotary table 520 to rotate.

[0053] <Second Embodiment> The injection molding machine 2 according to the second embodiment differs from the injection molding machine 1 according to the first embodiment in that a recess 529 is formed in the rotary table 520, extending from the bottom surface 528, and a recess 575 is not formed in the rotary shaft 570, extending from the front surface 576. The differences from the first embodiment will be described below. The same reference numerals are used for the same components in the first and second embodiments, and their detailed descriptions will be omitted.

[0054] Figure 4 is an example of a view of the rotary table 520 according to the second embodiment, seen from the rear towards the centerline. As shown in Figure 4, the rotary table 520 according to the second embodiment has multiple recesses 529 (four in Figure 4) that are recessed forward from the bottom surface 528 and extend radially from the center. The recesses 529 are formed between the multiple through holes 543 so as to be in a different position from the areas where the through holes 543 for passing the male threads of the bolts 550 are formed. On the other hand, the rotating shaft 570 according to the second embodiment does not have a recess 575 formed therein, and the front surface 576 is circular. Therefore, the recess 529 of the rotary table 520 forms a gap between it and the front surface 576 of the rotary shaft 570.

[0055] In the injection molding machine 2 configured as described above, a recess 529 is formed in the rotary table 520 according to the second embodiment. Therefore, the contact area between the bottom surface 528 of the rotary table 520 and the front surface 576 of the rotating shaft 570 is smaller than in the comparative configuration. In other words, in the area where the recess 529 is formed in the rotary table 520, air is interposed in the recess 529 between the rotary table 520 and the rotating shaft 570 (in other words, the rotary table 520 and the rotating shaft 570 are not in thermal contact). As a result, heat is less likely to be transferred from the rotary table 520 to the rotating shaft 570 in the injection molding machine 2. Therefore, in the injection molding machine 2, even if the rotary table 520 becomes hot due to the filling of the cavity space formed between the fixed mold 81 and the movable mold 82 with molding material, the rotating shaft 570 is less likely to become hot. As a result, the injection molding machine 2 can reduce the heat transferred to the inner ring of the bearing 580 compared to the comparative configuration. Thus, the injection molding machine 2 can suppress fluctuations in the gap between the inner and outer rings of the bearing 580.

[0056] Furthermore, in the injection molding machine 2, multiple recesses 529 are formed radially from the central part. This makes it possible to ensure that the heat transmitted through the front surface 576 of the rotating shaft 570 is distributed evenly in the circumferential direction. Furthermore, the rotary table 520 has multiple through holes 543 through which the male threads of the bolts 550 used to connect it to the rotary shaft 570 pass, and the recesses 529 are formed between the multiple through holes 543. This allows for easy connection between the rotary shaft 570 and the rotary table 520 while reducing the heat transmitted to the inner ring of the bearing 580.

[0057] <Third Embodiment> The injection molding machine 3 according to the third embodiment differs from the injection molding machine 1 according to the first embodiment in that it has a rotating shaft 370 that corresponds to the rotating shaft 570. The differences from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and third embodiments, and their detailed descriptions will be omitted.

[0058] Figure 5 is an example of a view of the rotation axis 370 according to the third embodiment, seen from the front in the direction of the centerline. As shown in Figure 5, the rotating shaft 370 according to the third embodiment differs from the rotating shaft 570 according to the first embodiment in that it is provided with multiple (four in Figure 5) fins 379 that protrude inward from the inner surface of the through hole 573. For example, the fins 379 can be provided over the entire area in the direction of the centerline of the through hole 573. If the through hole 573 is formed by machining, the fins 379 can also be machined out. Alternatively, the fins 379 may be formed separately from the base end portion 571 and the shaft portion 572, and then joined to the inner circumferential surface of the through hole 573, for example, by welding.

[0059] In the injection molding machine 3 configured as described above, heat from the rotating shaft 370 is dissipated by the fins 379. Therefore, the rotating shaft 370 is less likely to become hotter than the rotating shaft 570 in the first embodiment. In addition, in the injection molding machine 3, when the rotating shaft 370 rotates, airflow is generated by the fins 379, making it easier for the air in the recess 575 between the rotary table 520 and the rotating shaft 370 to be replaced with air in, for example, the through hole 573. In other words, it becomes easier to dissipate heat from the recess 575. Therefore, in the injection molding machine 3, heat is less likely to be transferred from the rotary table 520 to the rotating shaft 570 than in the injection molding machine 1 in the first embodiment. From these points, the injection molding machine 3 can reduce the heat transferred to the inner ring of the bearing 580 compared to the injection molding machine 1. As a result, the injection molding machine 3 can suppress fluctuations in the gap between the inner and outer rings of the bearing 580.

[0060] Furthermore, the fins 379 protruding inward from the inner surface of the through hole 573 may also be applied to the injection molding machine 2 according to the second embodiment. By having the fins 379 in the rotating shaft 570 according to the second embodiment, the heat transmitted to the inner ring of the bearing 580 can be reduced even further than in the injection molding machine 2 described above, and fluctuations in the gap between the inner and outer rings of the bearing 580 can be suppressed. [Explanation of Symbols]

[0061] 1,2,3…Injection molding machine, 81…Fixed mold (example of first mold), 82…Movable mold (example of second mold), 100…Clamping device, 110…Fixed platen, 120…Movable platen (example of support member), 370,570…Rotating shaft, 379…Fin, 400…Frame, 500…Control device, 520…Rotating table (example of holding member), 528…Bottom surface (example of first surface), 529,575…Recess, 550…Bolt (example of fastening member), 573…Through hole, 574…Female thread, 576…Front surface (example of second surface), 580…Bearing

Claims

1. A holding member that holds the second mold which forms a cavity space together with the first mold, A rotating shaft is positioned to protrude from the side of the holding member opposite to the side that holds the second mold, and to transmit the rotational force of the holding member, or to transmit rotational force to the holding member. A support member that rotatably supports the holding member via a bearing into which the rotating shaft is fitted, Equipped with, The holding member and the rotating shaft are arranged such that a first surface of the holding member facing the rotating shaft and a second surface of the rotating shaft facing the holding member are in contact with each other. A recess is formed in the rotating shaft that forms a gap between the second surface and the first surface, or a recess is formed in the holding member that forms a gap between the first surface and the second surface. Injection molding machine.

2. The rotating shaft has a through hole formed in the center in the direction of the rotational centerline, and a recess formed in the second surface extending from the through hole to the outer circumference. The injection molding machine according to claim 1.

3. The aforementioned recesses are formed in a plurality of ways radiating from the through hole. The injection molding machine according to claim 2.

4. The rotating shaft has multiple female threads formed on its second surface, into which the male threads of a fastening member used for connecting with the holding member are tightened, and the recesses are formed between the multiple female threads. The injection molding machine according to claim 2.

5. The aforementioned rotating shaft has a through hole formed in the center in the direction of the rotational centerline. The holding member has a plurality of recesses formed in the first surface that extend radially from the central part. The injection molding machine according to claim 1.

6. The rotating shaft is provided with fins that protrude inward from the inner surface of the through hole. An injection molding machine according to any one of claims 2 to 5.

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