JP7440687B2 - mold clamping device - Google Patents

Description

The present invention provides a mold opening/closing mechanism that moves a movable platen on which a movable mold is attached to a fixed platen on which a fixed die is attached in a mold opening/closing direction along tie bars, and a mold clamping mechanism for clamping the fixed die and the movable die. This invention relates to a mold clamping device equipped with a mold clamping mechanism.

Regarding the mold clamping device, the overall length is an issue due to the installation space in the factory. Compared to a toggle type mold clamping device, which has a fixed platen, a movable platen, and a pressure receiving plate, and a toggle mechanism between the movable platen and the pressure receiving plate, this type has a fixed platen and a movable platen, and has a mold opening/closing mechanism and a mold clamping mechanism. It is known that a separately provided mold clamping device can shorten the overall length. In response to the above-mentioned circumstances, Patent Document 1 is devised to further shorten the overall length of the mold clamping device by providing the ejector plate of the ejector device on the side of the drive unit that is away from the back surface of the movable platen. .

Furthermore, regarding mold clamping devices, the weight of the fixed platen and movable platen poses a problem. The weight of a fixed platen or movable platen is directly related to the cost of the fixed platen or movable platen itself. Furthermore, the weight of the movable platen is directly linked to the cost of the mechanism itself for moving the movable platen and the running cost when moving the movable platen. Furthermore, especially for large-sized mold clamping equipment, the weight of the fixed platen and movable platen is directly linked to the transportation cost when moving the mold clamping equipment from the manufacturing factory to the customer's factory, and in some cases, there may be restrictions on the vehicles and roads that can be transported. I may receive it. In response to the above-mentioned circumstances, Patent Document 2 further attempts to reduce the weight of the movable platen by making extensive use of a rib structure.

Japanese Patent Application Publication No. 2007-290184 Japanese Patent Application Publication No. 8-267463

However, in the ejector device of the mold clamping device of the injection molding machine of Patent Document 1, the ejector plate 45 is provided on the back side further than the back surface 25a of the movable platen, so the overall length of the mold clamping device may not be shortened so much. Ta. Further, in Patent Document 1, the portion of the movable platen through which the tie bar is inserted is slightly thicker than the central portion, but is entirely solid, and it is not possible to reduce the weight of the platen. Furthermore, the movable platen of the mold clamping device of Patent Document 2 has a thick central part as a solid boss 20c, so special measures are required when installing the ejector mechanism etc. In some cases, the overall length of the device became longer.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

A mold clamping device according to an embodiment includes a mold opening/closing mechanism that moves a movable platen to which a movable mold is attached to a fixed platen to which a fixed die is attached in a mold opening/closing direction along tie bars; In the mold clamping device equipped with a mold clamping mechanism for clamping a movable mold, the fixed platen or the movable platen is adjacent to an extended portion of a tie bar insertion part through which a tie bar is inserted on the back side of the plate. The connecting portion includes a connecting portion that connects the portions including the extended portion of the tie bar insertion portion and has a hollow portion inside.

The mold clamping device includes a mold opening/closing mechanism that moves a movable platen, on which a movable mold is attached, in a mold opening/closing direction along tie bars with respect to a fixed platen, on which a fixed die is attached, and a mold opening/closing mechanism that moves the movable platen, on which a movable mold is attached, in the mold opening/closing direction, and In a mold clamping device equipped with a mold clamping mechanism for clamping, the fixed platen or the movable platen has an extending portion of a tie bar insertion portion through which a tie bar is inserted, and an extension portion of an adjacent tie bar insertion portion on the back side of the plate. Since the parts including the parts are connected to each other and the connecting part has a hollow part inside, it is possible to reduce the weight of the fixed platen or the movable platen, shorten the overall length of the mold clamping device, suppress the weight of the fixed platen or the movable platen, and clamp the mold. At least one of the following can be achieved: suppressing the overall length of the device in a well-balanced manner.

It is a side view of the mold clamping device of the injection molding machine of 1st Embodiment. FIG. 2 is a front view of the movable platen and the like of the first embodiment as viewed from direction A in FIG. 1. FIG. FIG. 3 is a perspective view of the movable platen main body of the first embodiment. 3 is a view of the movable platen and the like of the first embodiment taken along the line BB in FIG. 2. FIG. 3 is a view of the movable platen and the like of the first embodiment taken along the line CC in FIG. 2. FIG. 2 is a view of the movable platen main body of the first embodiment taken along the line DD in FIG. 1. FIG. It is a side view of the mold clamping device of the injection molding machine of 2nd Embodiment.

Hereinafter, specific embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Further, in order to clarify the explanation, the following description and drawings are appropriately simplified. In addition, hatching is omitted in some parts to avoid cluttering the drawings.
<Schematic configuration of mold clamping device>

An outline of a mold clamping device 2 of an injection molding machine 1 according to an embodiment of the present invention will be explained with reference to FIG. FIG. 1 is a side view of the mold clamping device 2 of the injection molding machine 1 in the mold-closed state, and in the upper half of the center line of the dashed-dotted line, a hidden line is drawn as a broken line for the longitudinal section of the center of the mold clamping device, and the center line In the lower half of the figure, a vertical section of the axial center of the tie bar of the mold clamping device is shown with a hidden line and a broken line. The injection molding machine 1 includes a mold clamping device 2 and an injection device 4 on a base 3. The mold clamping device 2 includes two mold opening/closing mechanisms 15 that move a movable platen 14 on which a movable mold 13 is attached to a fixed platen 12 on which a fixed die 11 is attached, and two mold opening/closing mechanisms 15 for moving a movable platen 14 on which a movable die 13 is attached, and a movable platen 12 on which a fixed die 11 and a movable die 13 are attached. It is equipped with mold clamping cylinders 17 of four mold clamping mechanisms 16 that perform mold clamping. Note that the mold clamping mechanism 16 may use an electric motor. The injection device 4 also includes a screw (not shown) inside the heating cylinder 18, and a nozzle 19 at the tip of the heating cylinder 18.

A clamp device (not shown) is provided on the mold mounting surface 20 of the fixed platen 12 fixed on the base 3, and the fixed mold 11 can be mounted on the mold mounting surface 20 by the clamp device. Further, a mortar portion 22 for inserting the nozzle 19 of the injection device 4 is provided at the center of the back surface 21 of the fixed platen 12 on the opposite side to the mold mounting surface 20, and a fixed plate is provided at the center of the mortar portion 22. The mold 11 is provided with a hole to which the nozzle 19 is connected. Further, mold clamping cylinders 17 of the mold clamping mechanism 16 are provided near the four corners inside the fixed platen 12, respectively. In the mold clamping cylinder 17, a rod on the front side of the piston 23 constitutes a tie bar 24. Therefore, in the present invention, tie bars 24 are attached to the fixed platen 12. The mold clamping cylinder 17 is a double-acting cylinder having a mold clamping side oil chamber 25 on the front side of the piston 23 and a strong mold opening side oil chamber 26 on the rear side of the piston 23. Further, the mold clamping cylinder 17 is connected to a hydraulic system (not shown). Further, a position adjustment mechanism 32 for the tie bar 24 is provided on the back surface 21 side of the stationary plate 12, so that the position of the tie bar 24 can be adjusted when an engagement groove 27 and a half nut 31 are engaged, which will be described later.

A plurality of engagement grooves 27 are formed at the outer periphery of each of the tie bars 24 near the distal end side thereof and have the same pitch over a predetermined length in the mold opening/closing direction. Each tie bar 24 is inserted into a tie bar insertion hole 28 provided near the four corners of the movable platen 14. The movable platen 14 is movable on the base 3 along the tie bars 24. The mold clamping device 2 may be provided with a tie bar holder on the back surface 29 side of the movable platen 14 on the base 3 to hold each tie bar 24 at a constant distance from the movable platen 14.

A clamp device (not shown) is provided on the mold mounting surface 30 of the movable platen 14, and the movable mold 13 can be attached to the mold mounting surface 30 by the clamp device. Further, a half nut 31 is attached near the tie bar insertion hole 28 on the back surface 29 of the movable platen 14 on the opposite side from the mold mounting surface 30. The half nut 31 can be engaged with the engagement groove 27 of the tie bar 24. Note that when a heating/cooling mold or a hot runner mold is used, a heat insulating plate is attached to the mold mounting surfaces 20 and 30 of the fixed platen 12 and the movable platen 14 as necessary.

Furthermore, two mold opening/closing mechanisms 15 are disposed on the base 3 for moving a movable platen 14, on which a movable mold 13 is attached, toward and away from a fixed platen 12, on which a fixed die 11 is attached. In this embodiment, the mold opening/closing mechanism 15 uses an electric mechanism, and includes a servo motor 33, a ball screw 34 of a ball screw mechanism, a ball screw nut 35, and the like. The servo motor 33 is connected to a control device (not shown). Note that the mold opening/closing mechanism may use a hydraulic cylinder.
<Explanation of movable plate>

Next, details of the movable platen 14 will be explained with reference to FIGS. 2 to 6. FIG. 2 is a front view of the movable platen etc. viewed from direction A in FIG. FIG. 3 is a perspective view of the movable platen main body. FIG. 4 is a view of the movable platen and the like of the first embodiment taken along the line BB in FIG. FIG. 5 is a view taken along the line CC in FIG. 2, showing the movable platen and the like of the first embodiment. FIG. 6 is a view of the movable platen main body of the first embodiment taken along the line DD in FIG.

In this specification, the movable platen main body 39 of the movable platen 14 refers to a block to which other members are not attached. The movable platen main body 39 is made of cast iron and is later machined for the purpose of achieving surface accuracy and forming bolt holes, etc., and other members are attached to form the movable platen 14. The movable platen main body 39 includes a mold mounting part 40 having a mold mounting surface 30 to which the movable mold 13 is mounted, and an extension part 41 connected to the back side of the mold mounting part 40. The extension portion 41 connects the extension portions 44, 44 of the tie bar insertion portion through which adjacent tie bars 24 are inserted, or the portions including the extension portions 44, 44 of the tie bar insertion portion, respectively, and has a cavity inside. A connecting portion 46 having a portion 45 is provided. The movable platen main body 39 is described by giving names such as the mold attachment part 40, the extension part 44 of the tie bar insertion part which is the extension part 41, and the connecting part 46. Since it is integrally molded using a method such as the above, there are no clear boundaries between each part.

To explain the movable platen main body 39 in more detail, the mold mounting part 40 includes a mold mounting surface 30 to which the movable mold 13 is mounted, and the mold mounting surface 30 has a mold clamping device (not shown), bolt holes, Equipped with various valves, etc. for molds. Tie bar insertion holes 28 into which the tie bars 24 are inserted are provided near the four corners of the mold attachment portion 40 . The part of the mold attachment part 40 that is provided with the tie bar insertion hole 28 is a part 43 of the tie bar insertion part 42 on the side of the mold attachment surface, and the tie bar insertion hole 28 in the said part has a bush that guides the tie bar 24. (not shown) is fitted. Furthermore, a rod hole 48 for the ejector rod 47 described above and the like are formed on the center side of the mold mounting portion 40. The mold attachment part 40 has a tie bar insertion hole 28, a rod hole 48 for the ejector rod 47, a bolt hole (not shown), etc., but the other parts are solid members.

An extending portion 41 is formed on the back side of the mold mounting portion 40 of the movable platen main body 39. As shown in the cross section of the tie bar portion on the lower half side of the movable platen main body 39 in FIG. 4, and as shown in FIG. An extension portion 44 of the tie bar insertion portion, which is a side portion, is formed. The extending portion 44 of the tie bar insertion portion is a substantially cylindrical member having a tie bar insertion hole 28 into which the tie bar 24 is inserted at an axial center portion in the mold opening/closing direction. However, the extending portion 44 of the tie bar insertion portion does not necessarily have a donut-shaped cross section in connection with other portions to be described later.

Further, as shown in FIGS. 5 and 6, from the extension part 44 of the tie bar insertion part of the extension part 41 on the back side of the movable platen 14 toward the center O of the movable platen, the width is wider than the diameter of the tie bar 24. A radial thick wall portion 49 is formed. The extended portion 44 of the tie bar insertion portion and the radially thick portion 49 inside thereof are the mold clamping force transmitting portion 36 that transmits the most mold clamping force during mold clamping directly to the movable mold 13. Regarding the length of the radial thick wall portion 49 in the mold opening/closing direction, the length of the portion located near the extension portion 44 of the tie bar insertion portion is the length of the portion located near the extension portion 44 of the tie bar insertion portion or the connecting portion described below. It has the same length as 46. However, the length of the radial thick wall portion 49 on the side of the center O of the movable platen 14 in the mold opening/closing direction is as shown in FIGS. 3 and 5. It is shorter than the length in the direction. This is mainly to reduce the weight of the movable platen 14, and in anticipation of the safety factor against the stress of the movable platen body 39 during mold clamping, it is necessary to In areas where there is no problem, the plate thickness in the mold opening/closing direction is thinner.

Then, the radial thickness of the extending portions 44 of adjacent tie bar insertion portions of the extension portions 41 connected to the back surface of the mold attachment portion 40, or the extension portions 44 of adjacent tie bar insertion portions and other members. A connecting portion 46 is formed by connecting the flesh portions 49 to each other. As shown in FIGS. 2 and 6, the connecting portion 46 is formed by extending portions 44, 44 of adjacent tie bar insertion portions through which the upper two tie bars 24 are inserted, or extending portions 44 of the tie bar insertion portions. an upper horizontal connecting part 50 that connects parts including the upper horizontal connecting part 50, extension parts 44, 44 of adjacent tie bar insertion parts into which the lower two tie bars 24 are respectively inserted, or a part including the extension part 44 of the tie bar insertion parts. The lower horizontal connecting portion 51 that connects the two tie bars 24 on the operating side, the extension portions 44, 44 of adjacent tie bar insertion portions through which the two tie bars 24 on the operating side are inserted, or the portions including the extension portions 44 of the tie bar insertion portions. The operation side vertical connection part 52 to be connected, the extension parts 44, 44 of the tie bar insertion part through which the two tie bars 24 on the non-operation side are respectively inserted, or the parts including the extension parts 44, 44 of the tie bar insertion part are connected to each other. It consists of four connecting parts including a vertical connecting part 53 on the opposite operation side. Therefore, the extending portions 44, 44 of the tie bar insertion portions located in the diagonal direction of the movable platen 14 (for example, the extending portions 44 of the tie bar insertion portions at the upper part of the operating side and the lower part of the non-operating side) are the same as those of the adjacent tie bar insertion parts. The extending portions 44 are not connected to each other and are not connected by the connecting portion 46.

As shown in FIGS. 2 to 6, the back side of the movable platen 14 has a frame-shaped extension portion 41 projecting from the above-described members. Note that in the present invention, the frame shape includes those having irregularities, curved surfaces, flat surfaces with changing angles, etc. on the outer wall surface and inner wall surface of the extension portion 41, and is not limited to a completely square shape. Further, as shown in FIGS. 1 and 6, a support portion 54 for placing the movable platen 14 on the base 3 is provided on the lower surface side of the extension portions 44, 44 of the lower tie bar insertion portion. A leg portion 55 to which a wheel or a ball is attached is attached to the support portion 54. The leg portions 55 then move on the rails 56 on the base 3.

Due to the above structure, the movable platen 14 has a relatively thin plate thickness in the mold opening/closing direction on the center side of the mold mounting part 40 when viewed from the direction of arrow A in FIG. Since the extending portion 41 consisting of the extending portion 44 of the tie bar insertion portion, the connecting portion 46, etc. is provided on the back side of the mold attaching portion 40, the plate thickness in the mold opening/closing direction is increased. As shown in FIGS. 3 to 5, a recess 57 is formed inside the frame-shaped extension 41 on the back side of the movable plate 14. Inside the recess 57, on the four corner sides of the extension portion 44 of each tie bar insertion portion, there is a block-shaped thick wall portion protruding from the back surface 59 of the mold mounting portion 40 of the radial thick wall portion 49. 58 is formed. Note that the thick portion 58 is a portion that is projected to overlap with a part of the movable mold 13 attached to the movable platen 14 when projected from the direction of arrow A in FIG. Therefore, as shown in FIG. 5, most of the reaction force from the movable mold 13 during mold clamping is applied not to the thin wall portion 60 of the mold mounting portion 40 but to the radial direction thickness connected to the mold mounting portion 40. It is transmitted to the entire frame-shaped extension portion 41 including the connecting portion 46 via the thick portion 58 of the meat portion 49 . Further, the cross-shaped portion in FIG. 2 other than the thick wall portion 58 of the back surface 59 of the mold mounting portion 40 corresponding to the bottom of the recess 57 is a thin wall portion 60 having a thinner plate thickness. A rod hole 48 for the ejector rod 47 is formed in the thin portion 60. Note that in the first embodiment, the thick portion 58 is drawn solid, but it is possible to further reduce the weight by providing a plurality or a single elongated hole or circular hole from the back side toward the mold mounting surface 30 side. It's okay. In that case, the depth of the hole is preferably about the same depth as the position of the back surface 59 of the thin wall portion 60 of the mold attachment portion 40, or a slightly shallower depth.

The connecting portion 46 will be further explained with reference to FIGS. 3 to 6. Although the shapes of the respective connecting portions 46 are slightly different, since they are functionally the same, the upper horizontal connecting portion 50 will be described. The upper horizontal connection portion 50 includes an outer connection portion 61 that connects the extension portions 44 of the tie bar insertion portions, and an inner connection portion that connects the radial thick portions 49 that include the extension portions 44 of the tie bar insertion portions. A hollow portion 45 is provided between the two to reduce weight. Although one cavity 45 is formed in the first embodiment, a plurality of cavities 45 may be provided, or ribs or pillars connecting the outer connecting part 61 and the inner connecting part 62 may be provided inside the cavity 45. It may be provided. Note that the outer connecting portion 61 and the inner connecting portion 62 of the connecting portion 46 only need to be connected between portions including the extension portion 44 of the tie bar insertion portion.

As shown in FIGS. 3 and 5, the outer connecting portion 61 is a portion that constitutes the outer wall surface 38 of the outer side wall portion of the movable platen 14. As shown in FIGS. A hole 63 is also formed in the outer connecting portion 61 to connect the outer side and the hollow portion 45 for the purpose of weight reduction. Although the shape and number of the holes 63 are not limited, in the first embodiment, a rib 64 is formed in the mold opening/closing direction at an intermediate position between the tie bar insertion portions of the outer connecting portion 61, and holes are formed on both sides of the rib 64. A portion 63 is formed. The hole 63 is also necessary to provide the cavity 45 during casting of the movable platen body 39, and as a result, the cavity 45 is an open cavity connected to the outside world through the hole 63. Further, in the first embodiment, the outer connecting portion 61 is connected from the inner side of the extending portion 44 of the tie bar insertion portion, and there is a recess between the extending portion 44 of the tie bar insertion portion and the outer wall surface 38 of the outer connecting portion 61. A groove portion 65 is formed to avoid stress concentration in this portion. Note that the number and number of the ribs 64 and holes 63 are not limited, and the grooves 65 are not essential either. Further, the outer connecting portion 61 may be shaped like a curved plate, and its thickness may be uniform or uneven.

As shown in FIGS. 3 and 5, the inner connecting portion 62 is a portion that constitutes an inner wall surface 66 of the inner wall portion in the mold opening/closing direction of the recess 57 formed on the back side of the movable platen 14. A hole 67 connecting the cavity 45 and the recess 57 is also formed in the inner connecting portion 62 for the purpose of weight reduction. Although the shape and number of the holes 67 are not limited, in the first embodiment, one hole 67 is formed in the inner connecting portion 62 at the intermediate portion between the thick portions 58. ing. Note that the number of holes 67 is not limited. In the first embodiment, the thickness of the connecting portion 46 formed by the outer connecting portion 61 and the inner connecting portion 62 (the distance between the outer wall surface 38 of the outer connecting portion 61 and the inner wall surface 66 of the inner connecting portion 62) is , is larger than the diameter of the tie bar 24. The fact that the thickness of the connecting part 46 is larger than the diameter of the tie bar 24 is useful for making the movable platen main body 39 into a box-like structure and increasing its strength. It is also useful for securing a space for attaching the half nut 31. The inner connecting portions 62 may be connected to the portions of the extension portions 44, 44 of the tie bar insertion portions on the side of the center O of the movable platen 14, respectively. Further, the inner connecting portion 62 is not limited to a flat plate shape, but may be a curved plate shape or a bent flat plate shape. Further, the thickness of the inner connecting portion 62 may be uniform or uneven.

As shown in FIG. 3 and the like, a recess 57 is formed on the back surface 29 side of the movable platen 14. In the first embodiment, the recessed portion 57 is composed of the inner wall surface 66 of the inner connecting portion 62 of the frame-shaped extension portion 41, the thick wall portion 58 of the radial thick wall portion 49, and the back surface 59 of the mold attachment portion 40. be done. However, the inner wall surface 66 of the inner connecting portion 62 and the back surface 59 of the mold attachment portion 40 may be used. Since the movable platen 14 has a box-shaped structure including the frame-shaped extension portion 41 and the recessed portion 57 inside thereof, it is advantageous in terms of strength and also in terms of installation space for the ejector mechanism 72, etc., which will be described later. It's advantageous. Note that the recessed portion 57 does not exclude a case in which a rib is further provided.

Further, as shown in FIGS. 2 and 3, a back plate portion 68 is provided on the back side of the frame-shaped extension portion 41. The back plate portion 68 is a flat surface perpendicular to the mold opening/closing direction in order to attach the ejector servo motor 71 and a half nut 31 described below. Further, in the first embodiment, the four inner corners of the back plate portion 68 are curved. The inner peripheral side of the back plate portion 68 may be the same surface as the inner wall surface 66 of the inner connecting portion 62, or may be provided with a projecting portion so that the opening of the recess portion 57 becomes smaller. As shown in FIG. 4, etc., tie bar insertion holes 28 are formed near the four corners of the back plate portion 68, and a bush (not shown) for guiding the tie bar 24 is inserted into the portion of the tie bar insertion hole 28 that contacts the back side. has been done.

As shown in FIGS. 1 and 2, a pair of nuts with engaging teeth that are engaged with the engaging grooves 27 of the tie bars 24 are provided on the surface of the back plate portion 68 near the tie bar insertion holes 28. A half nut 31 is attached to each half nut. In the half nuts 31 of this embodiment, the nuts of the two half nuts 31 are opened and closed in the horizontal direction by an actuator 37 such as a single servo motor. Note that the structure of the half nut 31 is not limited to this. Further, a bracket 70 for mounting an ejector servo motor is formed on the back surface 29 of the back plate portion 68. Note that if the top priority is to shorten the total length of the mold clamping device 2 in the mold opening/closing direction and allowing the total width of the mold clamping device 2 to increase between the operation side and the non-operation side, only the drive shaft and drive pulley should be The ejector servo motor 71 may be attached to the side surface of the movable platen 14 so as to slightly protrude from the back surface 29 toward the side opposite to the mold attachment surface.

Note that the back plate portion 68 is not essential in the present invention, and the back surface 29 of the extension portion 44 of the tie bar insertion portion and the back surface 29 of the connecting portion 46 may directly constitute the back surface 29 of the frame-shaped extension portion 41. good. In that case, the rear surface of the extension portion 44 of the tie bar insertion portion and the rear surface of the connecting portion 46 may have different heights. In other words, either one of the movable platen bodies 39 may be higher, and the thickness of the movable platen body 39 may be determined by the raised portion. Further, it is also not essential to provide a half nut on the rear surface of the extension portion 44 of the tie bar insertion portion of the frame-shaped extension portion 41. That is, the half nut may be provided on the fixed platen 12 instead of the movable platen 14 of the first embodiment. Further, the back side portions of the outer connecting portion 61 and the inner connecting portion 62 may not have a back plate in part or in whole. Therefore, the cavity 45 in the present invention includes a concave portion.

In the movable platen 14 having the above structure, the mold mounting surface 30 of the movable platen 14 and the half nut 31 are different from the length E of one side of the mold mounting surface 30 of the movable platen 14 shown in FIGS. 2 and 4. The ratio of the length F (thickness of the movable platen in the mold opening/closing direction) to the attached back surface 29 is increased. Specifically, the ratio (E/F) obtained by dividing the length E of the side of the movable plate 14 by the length F of the plate thickness is not limited to this, but may be set to 35% to 50%. preferable. Furthermore, if the thickness of the movable platen 14 is made too thick, the overall length of the mold clamping device 2 will become long, so it is more desirable to set the thickness to 37% to 45%. Furthermore, the relationship between the thickness G of the thin wall portion 60 of the mold mounting portion 40 and the length F of the plate thickness of the movable platen 14 is calculated by dividing the thickness G of the thin wall portion 60 of the mold mounting portion 40 by the length F of the plate thickness. Although the ratio (G/F) is not limited thereto, it is preferably 8% to 40%, and even more preferably 10% to 25%. The ratio (I/F) of the length I of the extension part 41 to the length F of the plate thickness of the movable platen 14 is calculated backward from the above ratio, and is preferably 60% to 92%, more preferably 75%. It is more desirable to set it to 90%.

Although the present invention is not completely limited, the main subject of the present invention is a mold clamping device that locks a tie bar with a half nut. In this type of mold clamping device that locks tie bars with half nuts, the movable platen or fixed platen has a movable platen or fixed platen that is perpendicular to the mold opening/closing direction between the center side where the mold is attached and the side near the four corners where the half nuts are attached. The distance in the direction is relatively long. The mold clamping force during mold clamping and the accompanying reaction force from the mold are mutually exerted between the center side of the movable platen or fixed platen, where the mold is attached, and the sides near the four corners where the half nuts are attached. As a result, the movable platen or fixed platen tends to flex during mold clamping. Therefore, the structure of the board of the present invention is particularly effective. On the other hand, the toggle type mold clamping device has a link attachment section on the back side of the movable platen, and has a different basic structure. Therefore, the present invention does not apply to toggle type mold clamping devices other than mold clamping devices that only open and close the mold using a toggle mechanism and then clamp the mold using another mechanism after engaging a half nut.

Next, the ejector mechanism 72 attached to the movable platen 14 will be explained with reference to FIGS. 2 and 4. As described above, the ejector servo motor 71 of the ejector mechanism 72 is fixed to the bracket 70 of the rear plate portion with the drive shaft to which the drive pulley 75 is attached facing toward the fixed platen. Further, as shown in FIG. 6, guide rods 77 protrude and are fixed in the four guide rod insertion holes 76 of the cross-shaped thin wall portion 60 of the mold mounting portion 40 of the movable platen main body 39 in the mold opening/closing direction. A support plate 78 is fixed to the distal end side of the guide rod 77 in parallel with the back surface 59 of the thin wall portion 60. The position of the support plate 78 in the mold opening/closing direction is such that its surface 79 on the side opposite to the mold mounting surface is approximately at the same position as the back surface 29 of the back plate portion 68. That is, the support plate 78 itself is completely inserted into the recess 57 of the movable platen 14 or is slightly protruding from the side view as shown in FIG. 4 and the like.

Two ball screws 80, 80 are rotatably attached to the support plate 78 by bearings, and driven pulleys 81, 81 are attached to the distal ends of the ball screws 80, 80, respectively. A timing belt 82 is stretched between the driving pulley 75 of the servo motor 71 and the two driven pulleys 81, 81. Further, the end portions of the ball screws 80, 80 on the opposite side from the tip side are rotatably supported by a bearing provided in the thin wall portion 60 of the mold mounting portion 40. Further, an ejector plate 83 is guided by the guide rod 77 so as to be movable in the mold opening/closing direction. Therefore, the ejector plate 83 is provided in the recess 57 formed by the wall surface including the inner wall surface 66 of the connecting portion 46 . Two ball screw nuts 84, 84 are fixed to the ejector plate 83, and the ball screws 80, 80 are inserted through the ball screw nuts 84, 84. Further, a plurality of ejector rods 47 are fixed to the mold mounting portion 40 side of the ejector plate 83 so as to face in the mold opening/closing direction.

As described above, the ejector rod 47 is inserted into the rod hole 48 formed in the mold attachment part 40 and further into the rod hole 74 of the movable mold 13. It is in contact with the back surface of the protruding plate 85 inside the movable mold 13. A plurality of protruding rods 87 are also formed on the cavity surface 86 side of the protruding plate 85 of the movable mold 13, and the protruding rods 87 are inserted into rod holes 88 formed toward the cavity surface 86. Further, the protruding rod 87 is returned to its original position by a spring 89. Note that the ejector mechanism 72 is not limited to the above configuration, and when an electric motor is used, a ball screw nut may be rotated to move the ball screw forward. Further, the ejector mechanism may use an electromagnet, a hydraulic cylinder, an air cylinder, or the like. In any case, since the majority of the ejector mechanism 72 including the ejector plate 83 is accommodated in the recess 57 formed by the frame-shaped extension 41, the entire length of the mold clamping device 2 and, by extension, the injection molding machine 1 is can be suppressed.

<Operation explanation of mold clamping device>
Next, a method of controlling the mold clamping device 2 of the injection molding machine 1 according to the first embodiment will be briefly described. First, the ball screw 34 is rotated by the operation of the servo motor 33 of the mold opening/closing mechanism 15 from the mold opening state in which the movable platen 14 has retreated, and the ball screw nut 35 inserted into the ball screw 34 is moved in the mold opening/closing direction. , the movable platen 14 and the movable mold 13, which had been stopped at the mold open position, are moved toward the fixed platen 12 and the fixed mold 11. When the movable mold 13 comes into mold contact with the fixed mold 11, a cavity c1 into which molten resin is injected is formed between the fixed mold 11 and the movable mold 13 (mold closing step). Next, each half nut 31 is operated, and the engagement teeth of the half nut 31 are engaged with the engagement groove 27 of each tie bar 24 (half nut engagement step).

Next, hydraulic oil is supplied to the mold-clamping side oil chamber 25 of the mold-clamping cylinder 17 of the mold-clamping mechanism 16, and the tie bar 24 is pulled, thereby increasing mold clamping pressure, and the fixed mold 11 and the movable mold 13 are pressurized. tightened (pressure increase process). When it is confirmed that a predetermined mold clamping force is achieved, the molten resin is then injected from the injection device 4 toward the cavity c1 (injection process/mold clamping process).

To explain the state of the fixed platen 12 and the movable platen 14 in the mold clamping process, the tie bar 24 is pulled by the mold clamping cylinder 17, and the tie bar 24 is pulled from the engagement groove 27 of the tie bar 24 to the movable platen 14 via the engagement tooth of the half nut 31. The mold clamping force is transmitted. The movable mold 13 is clamped against the fixed mold 11 by the mold clamping force transmitted from the extension portion 44 of the tie bar insertion portion of the extension portion 41 of the movable platen 14 to the mold mounting portion 40 . At this time, the reaction force from the mold side is generated conversely from the mold mounting portion 40 of the movable platen 14 toward the extension portion 41 side.

In this case, as in Patent Document 1, the length between the mold mounting surface of the movable plate and the back surface to which the half nut is attached (the length of the mold mounting surface of the movable platen) When the plate thickness (in the opening/closing direction) is small, the bending stress acting on the movable plate becomes large and the deflection of the movable plate becomes large. Furthermore, if it is attempted to suppress the deflection of the movable platen, it is necessary to increase the plate thickness of the movable platen, which increases the weight.

On the other hand, in the first embodiment, as described above, with respect to the length E of one side of the mold mounting surface 30 of the movable platen 14 shown in FIGS. 2 and 4, the mold mounting surface 30 of the movable platen 14 is half Since the length F between the back surface 29 to which the nut 31 is attached (thickness of the movable platen in the mold opening/closing direction) is large, the bending stress acting on the movable platen body 39 of the movable platen 14 is small, and the movable platen body 39 is Deflection becomes smaller. In the present invention, the extending portion 44 of the tie bar insertion portion extending in the mold opening/closing direction of the movable platen body and the radially thick portion 49 are connected by the connecting portion 46 to form a picture frame shape. Therefore, the tensile stress acting on the extension portion 41 can be received in a distributed manner, and as a result, the compressive stress acting on the mold attachment portion 40 can be reduced.

Further, in Patent Document 2, the cross rib is required to reach the center of the movable platen, but in the first embodiment, the length of the radial thick wall portion 49 does not need to be extended to the center of the movable platen 14. This makes it possible to ensure strength against bending of the plate during mold clamping, and at the same time, it is possible to form a recessed portion in the center of the back side of the movable plate 14. This is because the tensile stress acting on the back side of the thick radial wall portion 49 of the box-shaped movable platen 14 is dispersed by the outer connecting portion 61 and the inner connecting portion 62.

In the mold clamping step, the mold clamping cylinder 17 continues to clamp the mold for a predetermined period of time after injection, and the molten resin injected into the cavity c1 is cooled. When the mold clamping process is completed, the mold clamping side oil chamber 25 of the mold clamping cylinder 17 is connected to the drain, and the pressure of the hydraulic oil in the mold clamping side oil chamber 25 is reduced to 0 (pressure release process).

When the pressure release process is completed, hydraulic oil is supplied to the strong mold opening side oil chamber 26 of the mold clamping cylinder 17, and strong mold opening is performed (powerful mold opening process). When the movable platen 14 and the movable mold 13 are moved to a predetermined position by the strong mold opening process, the servo motor 33 of the next mold opening/closing mechanism 15 is activated to complete the mold opening of the movable platen 14 and the movable mold 13. Move it to the desired position (mold opening process). At the mold opening completion position, the molded product is ejected from the cavity surface 86 of the movable mold 13 by the operation of the servo motor 71 of the ejector mechanism 72, and is taken out by a take-out machine (not shown) (take-out step). Then, the process moves to the mold closing process of the next molding cycle.

To describe the operation of the ejector mechanism 72 in the ejecting process in more detail, when the servo motor 71 of the ejector mechanism 72 is operated, the rotational force of the drive pulley 75 is transmitted to the two driven pulleys 81, 81 via the timing belt 82. , two ball screws 80, 80 to which driven pulleys 81, 81 are fixed are rotated, respectively. As the ball screws 80, 80 rotate, the ball screw nuts 84, 84 are moved rightward in FIG. 4. As a result, the ejector plate 83 to which the ball screw nuts 84, 84 are fixed and the ejector rod 47 on the movable platen 14 side attached to the ejector plate 83 are simultaneously moved rightward in FIG. 4. The ejector rod 47 presses the back surface of the protrusion plate 85 in the movable mold 13, and the protrusion rod 87 fixed to the front side of the protrusion plate 85 is protruded from the cavity surface 86, so that a molded product (not shown) is ejected. .

<Second embodiment>
The second embodiment corresponds to claim 5 and FIG. In FIG. 7, the mold clamping device 102 of the injection molding machine 101 is shown in the mold open state, the upper half of the center line shows the center cross section of the movable platen 106, etc., and the lower half of the injection molding machine 101 shows A cross section of the tie bar 107 portion is shown. A mold clamping device 102 of an injection molding machine 101 according to the second embodiment moves a movable platen 106 to which a movable mold 105 is attached to a fixed platen 104 to which a fixed die 103 is attached in a mold opening/closing direction along tie bars 107. In a mold clamping device 102 equipped with a mold opening/closing mechanism 108 for moving and a mold clamping mechanism 109 for clamping the fixed mold 103 and the movable mold 105, the movable platen 106 is a mold to which the movable mold 105 is attached. A first movable platen 111 provided with a mounting surface 110 and a second movable platen 112 connected to the first movable platen 111 by a mold clamping mechanism 109, the second movable platen 112 is A board main body part 114 including an extension part 113 of a tie bar insertion part into which the tie bar 107 is inserted, and an extension of the tie bar insertion part which is formed on the outer edge of the back surface of the board main body part 114 and into which the tie bar 107 is inserted. A connecting portion 116 that connects the portions including the portion 113 and has a hollow portion 115 inside is provided, and a recess 117 is formed by a wall surface including the inner wall surface of the connecting portion 116. Inside the recess 117, An ejector plate 119 of the ejector mechanism 118 is arranged either on the first movable plate 111 or between the first movable plate 111 and the second movable plate 112.

That is, the mold clamping device 102 of the second embodiment has a first movable plate 111 to which a movable mold 105 is attached to a fixed plate 104 and a second movable plate comprising a mold clamping cylinder 120 of a mold clamping mechanism 109. A platen 112 is provided, and a ram 121 of a mold clamping cylinder 120 is fixed to the back surface of the first movable platen 111. The first movable platen 111 and the second movable platen 112 are moved to open and close the mold on the bed 122 by the operation of the mold opening/closing mechanism 108 relative to the fixed platen 104. A member including the extension portions 113 of the tie bar insertion portions and the extension portions 113 of the tie bar insertion portions extending to the four corners of the back side of the plate body portion 114 on which the mold clamping cylinder 120 of the second movable platen 112 is provided. The mold clamping force transmitting parts are connected to each other by connecting parts 116. As shown in the upper half of FIG. 7, the connecting portion 116 is provided with an outer connecting portion 123 and an inner connecting portion 124, with a hollow portion 115 formed between them.

A frame-shaped extension part 125 is formed by the extension part 113 of the tie bar insertion part, the mold clamping force transmission part, and the connection part 116, and the ejector plate 119 of the ejector mechanism 118 is installed inside the frame-shaped extension part 125. The majority of the parts, including the Furthermore, half nuts 128 are respectively attached to the vicinity of the tie bar insertion holes 127 on the back surface 126 of the extension portion 113 of the tie bar insertion portion of the frame-shaped extension portion 125 . When the mold clamping device 102 of the second embodiment clamps the mold, only the second movable platen 112 is bent and deformed by the mold clamping force. However, by changing the shape of the second movable platen 112 to include a frame-shaped extension portion 125, the ratio of the plate thickness in the mold opening/closing direction to the length of one side of the movable platen (for example, the length in the vertical direction) can be increased. Even if the weight is the same, the bending deformation during mold clamping can be reduced. In addition, in the second embodiment, when there is one mold clamping cylinder, the ejector mechanism 118 is installed in the first movable platen 111 or in the mechanical part between the first movable platen 111 and the second movable platen 112. may also be provided (the motor is attached to the side of the first movable platen 111).

<Other embodiments>
In the first embodiment described above, the mold clamping cylinder 17 is provided on the fixed platen 12, and the half nut 31 is provided on the movable platen 14 with respect to the tie bar 24 connected to the fixed platen 12. However, in the present invention, the movable platen may be provided with a mold clamping cylinder, and the fixed platen may be provided with a half nut. In this case, the mold mounting portion of the fixed plate is formed with a mortar portion in the center into which the injection device is inserted. Then, a frame-shaped extending portion is further formed from the back surface (anti-mold mounting surface) of the mold mounting portion other than the mortar portion toward the back side of the board. The extending portion includes a portion including an extending portion of the tie bar insertion portion through which the tie bar is inserted, and a connecting portion that connects the portions to each other. The connecting portion is composed of a plurality of ribs and beams to reduce weight, and has a hollow portion inside. A half nut is attached to each of the tie bar insertion holes on the back surface of the extending portion near the tie bar insertion holes through which the tie bars are inserted. In that case, the ejector mechanism may be attached to the inside of the frame-shaped extension and the recess formed by the mortar. Also in the second embodiment, the tie bar may be fixed to the second movable platen, a half nut may be provided to the fixed platen, and the structure of the present invention may be adopted for the fixed platen.

Furthermore, as another embodiment, a mold mounting section having a mold mounting surface to which a movable mold of a movable platen is mounted, and a mold mounting part having a mold mounting surface to which a fixed mold of a fixed platen is mounted. The portion may not be inserted through the tie bar. In that case, the board body is connected to the central pressing part on the back side of the mold attachment part. Alternatively, the pressing part at the center of the board body is connected to the mold attachment part. A tie bar insertion portion is formed in a portion of the board main body through which the tie bar is inserted. Further, the tie bar insertion portion extends from the board main body toward the back side, and a radial thick portion is formed from the extended portion of the tie bar insertion portion toward the center of the movable board. The radial thickened portion is also connected to the back side of the board body. Then, a connecting portion is formed that connects the extending portions of the tie bar insertion portions or the extending portions of the tie bar insertion portions and the radially thick portions. The extended portion of the tie bar insertion portion, the radially thick portion, and the connecting portion correspond to the extended portion that increases the thickness of the board. At least the connecting portion of the frame-shaped extension portion is hollow inside. Further, a half nut is attached near the tie bar insertion portion on the back side of the frame-shaped extension portion (the surface opposite to the mold attachment surface). In yet another embodiment, the recess formed on the back side of the board may be formed not by the mold attachment part but by the back wall surface of the board body and the inner wall surface of the extension part.

Moreover, the movable platen and fixed platen of the present invention may not be made of a single cast body as a whole, but may be made of a plurality of members joined together, as shown in Japanese Patent No. 5,567,066. That is, the mold attachment part, the board main body part, and the extension part may be cast separately and assembled later.

The connecting portion of the movable platen or the fixed platen may include connecting portions other than the outer connecting portion 61 and the inner connecting portion 62. The connecting portion includes a hollow portion, and a hole connecting the hollow portion to the outside, a hole connecting the hollow portions to each other, and a rib connecting the connecting portions to each other are provided as appropriate. Further, the connecting portion may have a honeycomb structure in which part or all of the connecting portion has a hollow portion inside. In this case, the shape of the honeycomb is not limited to hexagonal, but may be triangular or quadrangular. Alternatively, the connecting portion may include one or more cylindrical members each having a hollow portion therein in the mold opening/closing direction or in the direction connecting the extending portions of the tie bar insertion portions.

Further, the mold clamping device of the present invention may be a mold clamping device of a mold rotary injection molding machine in which a rotary table is attached to the surface of a fixed platen or a movable platen. In that case, the rotary table on which the mold is mounted on the mold mounting surface corresponds to the mold mounting part, and the plate main body of the movable plate or the fixed plate is connected to the back side of the mold mounting part. Further, on the outer periphery of the back side of the main body part, a frame-shaped extension part is formed of a member including an extension part of the tie bar insertion part of the present invention, a connecting part, and the like. A half nut is attached near the tie bar insertion portion on the back side of the extension portion. Further, a recess is formed from the back wall surface of the board main body portion and the inner wall surface of the extension portion. In the case of a mold rotary injection molding machine equipped with a rotary table, in addition to the ejector mechanism, the concave part is provided with a rotary motor of the rotary table, and piping for feeding a temperature control medium from the rotary shaft of the rotary table to the mold. It is also possible to provide a mechanism or the like.

Furthermore, the mold clamping device of the present invention may be one in which a rotatable intermediate plate is provided between the fixed plate and the movable plate. In that case, the plate provided with the connecting portion of the present invention may be at least one of a fixed plate and a movable plate. The use of the present invention is not very useful for a plate, such as the intermediate plate, which hardly deforms due to the mold clamping force applied during mold clamping. Further, in the mold clamping device of the present invention, a tie bar is passed between a fixed plate and a pressure receiving plate corresponding to the fixed plate, a movable plate is moved on the tie bar or the bed by a mold opening/closing mechanism, and the mold is clamped by the mold clamping mechanism. It may also be something that is done. In this case, the pressure receiving plate provided on the bed and moved only a small amount during mold clamping corresponds to the fixed plate of the present invention, and has a box-shaped structure with a recessed portion on the back side.

Furthermore, the mold opening/closing direction of the movable platen in the mold clamping device of the present invention is not limited to the horizontal direction, and may be a vertical mold clamping device in which the movable platen opens and closes the mold in the vertical direction. In that case, the movable platen of the present invention may be an upper plate whose mold is opened and closed above the fixed plate, or a lower plate whose mold is opened and closed below the fixed plate. Further, the present invention may be used for a fixed plate of a vertical mold clamping device. The mold clamping force of the mold clamping device of the injection molding machine of the present invention is not particularly limited, but as an example, it is more suitably used in a large mold clamping device with a mold clamping force of 8,000 kN or more.

Although the present invention will not be enumerated one by one, it is needless to say that it is not limited to the above-mentioned ones, and can be applied to any modifications made by those skilled in the art based on the gist of the present invention. The plurality of examples explained above can also be implemented in combination as appropriate. The control method using the mold clamping device of the present invention includes general mold clamping control that continues from the start of injection to the end of cooling in a completely pressurized state, injection compression molding control, injection press molding control, and foam molding control. It may also be used for control. Furthermore, the material to be molded and the type of molded product are not limited.

1 Injection molding machine 2 Mold clamping device 11 Fixed mold 12 Fixed platen 13 Movable mold 14 Movable platen 15 Mold opening/closing mechanism 16 Mold clamping mechanism 20, 30 Mold mounting surface 21, 29 Back side 24 Tie bar 31 Half nut 40 Mold mounting Part 41 Extension part 44 Extension part of tie bar insertion part 45 Cavity part 46 Connection part 57 Recessed part 60 Thin part 61 Outer connection part 62 Inner connection part 66 Inner wall surface 72 Ejector mechanism 83 Ejector plate

Claims (5)

a mold opening/closing mechanism that moves a movable platen to which a movable mold is attached to a fixed platen to which a fixed die is attached in a mold opening/closing direction along tie bars; and a mold clamping mechanism to clamp the fixed die and the movable die. In a mold clamping device equipped with
an ejector mechanism disposed on the back side of the fixed platen or the movable platen and ejecting the molded product from a cavity surface of the fixed mold or the movable mold, which is attached to a mold mounting surface on the opposite side to the back side;
thick-walled portions formed at four corners of a recess on the back side of the fixed plate or the movable plate;
a thin wall portion formed at a bottom portion other than the thick wall portion in a recess on the back side of the fixed platen or the movable platen;
A mold clamping device equipped with The ejector mechanism includes an ejector plate and an ejector rod fixed to the ejector plate,
An ejector plate is provided in the recess,
A rod hole into which the ejector rod is inserted is formed in the thin wall portion.
The mold clamping device according to claim 1 . The ejector plate is movable in the mold opening/closing direction and is provided opposite to the thin wall portion.
The mold clamping device according to claim 2 . The ejector plate is movable in the mold opening/closing direction and is provided in a cross-shaped recess formed by the side surface of the thick part and the bottom of the thin part.
The mold clamping device according to claim 2 or claim 3 . A hole is provided in the thick part from the back side,
The mold clamping device according to any one of claims 1 to 4 .

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