Molding device

Abstract

Provided is a mold clamping device capable of preventing in advance a movable platen from damaging a tie bar. A mold clamping device (1) is provided with: a movable platen (3) that moves along a tie bar (4); a driving mechanism (10) that has a plurality of elevating mechanisms (10A, 10B, 10C, 10D, ...) including a first elevating mechanism (10A) and a second elevating mechanism (10B), and that is configured to be capable of introducing a difference (β) so that a first portion (3A) of the movable platen (3) corresponding to the first elevating mechanism (10A) is set at a higher or lower position than a second portion (3B) of the movable platen (3) corresponding to the second elevating mechanism (10B), the driving mechanism (10) moving the movable platen (3); and a connecting structure (20) that connects the driving mechanism (10) to the movable platen (3). The connecting structure (20) is configured as a stopper that restricts movement of the movable platen (3) so that the difference (β) does not become greater than a prescribed value (α).

Description

[Technical field]

[0001] The present invention relates to a mold clamping device equipped with a plurality of lifting mechanisms. [Background technology]

[0002] There is a demand to minimize the total thickness variation (TTV), which is the difference between the maximum and minimum thicknesses of a resin-encapsulated product. To minimize the TTV, the upper and lower dies must be arranged parallel to each other by adjusting the distance between the fixed platen and the movable platen with high precision during clamping. For example, Patent Documents 1 and 2 propose a clamping device that includes multiple lifting mechanisms and can arbitrarily adjust the height of the movable platen for each part corresponding to each lifting mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-324377 A [Patent Document 2] JP 2008-087408 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the clearance between the movable platen and the tie bars that guide its elevation is very small, if the difference in height between the elevation mechanisms becomes too large, the movable platen may tilt excessively and damage the tie bars. Therefore, an object of the present invention is to provide a mold clamping device that can prevent the movable platen from damaging the tie bars. [Means for solving the problem]

[0005] A mold clamping device according to one aspect of the present invention includes a movable platen that moves along tie bars, and a plurality of lifting mechanisms including a first lifting mechanism and a second lifting mechanism, and is configured to be able to provide a difference such that a first portion of the movable platen corresponding to the first lifting mechanism is at a higher or lower position than a second portion of the movable platen corresponding to the second lifting mechanism, and includes a drive mechanism that moves the movable platen, and a connecting structure that connects the drive mechanism to the movable platen. The connecting structure is configured as a stopper that restricts movement of the movable platen so that the difference does not exceed a predetermined value.

[0006] According to this aspect, even if an attempt is made to increase the difference beyond the predetermined value, the connecting structure restricts movement of the movable platen, thereby making it possible to prevent the movable platen from tilting excessively and damaging the tie bars.

[0007] In the above aspect, the coupling structure may include a plurality of couplings attached to the first lifting mechanism.

[0008] According to this aspect, it is possible to distribute stress among a plurality of connecting structures in each lifting mechanism, which is suitable for use when the lifting mechanism is, for example, a ball screw or the like that generates a large rotational load around its axis.

[0009] In the above aspect, each of the multiple connectors may have a free shank structure having a predetermined range of motion.

[0010] According to this aspect, it is possible to restrict the movement of the movable platen so that the difference does not exceed a predetermined value with a simple configuration that is easily available.

[0011] In the above aspect, the movable platen may be configured to be able to slide smoothly on the tie bar surface when the difference is equal to a predetermined value.

[0012] According to this aspect, if the difference is equal to or smaller than a predetermined value, a correction value for the difference can be added and all of the lifting mechanisms can be driven at a uniform speed while keeping the movable platen tilted, thereby performing operations such as mold closing and mold opening.

[0013] In the above aspect, the drive mechanism may include four lifting mechanisms.

[0014] According to this aspect, the lifting mechanisms can be arranged so that the nearest lifting mechanism is equidistant from each of the four tie bars, including the four lifting mechanisms. The movable platen can be moved by transmitting forces to each part in a well-balanced manner. Effect of the Invention

[0015] According to the present invention, it is possible to provide a mold clamping device that can prevent the movable platen from damaging the tie bars. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing a mold clamping device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view of the movable platen shown in FIG. [Diagram 3] FIG. 3 is an enlarged cross-sectional view of the connection structure shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, components with the same reference numerals have the same or similar configurations. One embodiment of the present invention is a mold clamping device 1 that clamps upper and lower molds in compression molding or transfer molding. By attaching an upper mold and a lower mold between a fixed platen 2 and a movable platen 3, a resin sealing device that seals semiconductor chips and the like with resin can be configured. The present invention will be described in detail below with reference to the drawings.

[0018] Fig. 1 is a cross-sectional view showing a mold clamping device 1 according to one embodiment of the present invention, taken along a plane passing through the centers of shafts 11 of first and second lifting mechanisms 10A and 10B described below. As shown in Fig. 1, the mold clamping device 1 includes a cylindrical tie bar 4 extending vertically, a fixed platen (also called a "fixed platen") 2 fixed to an end of the tie bar 4, a movable platen (also called a "movable platen") 3 moving vertically along the tie bar 4, a drive mechanism 10 that moves the movable platen 3 vertically, a connecting structure 20 that connects the drive mechanism 10 to the movable platen 3, and the like.

[0019] The drive mechanism 10 is composed of a plurality of lifting mechanisms (10A, 10B, ...) including first and second lifting mechanisms 10A, 10B. In the illustrated example, the fixed platen 2 is disposed on the upper side and the movable platen 3 is disposed on the lower side, but the fixed platen 2 may be disposed on the lower side and the movable platen 3 may be disposed on the upper side. Each of the lifting mechanisms 10A, 10B, ... is composed of, for example, ball screws (11, 12, 13, 14), a motor 15, a transmission mechanism (not shown), etc.

[0020] The transmission mechanism is not shown, but is composed of, for example, a reducer, a belt, a pulley, etc. The ball screw is composed of a shaft portion 11, a nut 12, a ring 13, a fastening screw 14, etc. The shaft portion 11 extends parallel to the extension direction of the tie bar 4, and is rotationally driven by a servo-controlled motor 15 via the transmission mechanism. When the shaft portion 11 rotates, the nut 12 moves linearly in the vertical direction. The ring 13 is fixed to the nut 12 by a plurality of fastening screws 14.

[0021] The mold clamping unit 1 can move the movable platen 3 with a difference β so that a first portion 3A (shown in FIG. 2) corresponding to the first lifting mechanism 10A is at a higher or lower position than a second portion 3B (shown in FIG. 2) corresponding to the second lifting mechanism 10B. These multiple lifting mechanisms (10A, 10B, ...) that cooperate to move the movable platen 3 up and down are collectively referred to as a drive mechanism 10.

[0022] Fig. 2 is a plan view that shows a schematic diagram of the movable platen 3 shown in Fig. 1. In the example shown, the drive mechanism 10 of the mold clamping unit 1 includes four lifting mechanisms 10A, 10B, 10C, and 10D. The drive mechanism 10 may be configured with three or less lifting mechanisms, or may be configured with five or more lifting mechanisms. Each of the lifting mechanisms 10A, 10B, 10C, and 10D presses a corresponding portion 3A, 3B, 3C, or 3D that is located directly above the lifting mechanism.

[0023] In the illustrated example, the first and second lifting mechanisms 10A, 10B of the first to fourth lifting mechanisms 10A, 10B, 10C, 10D are aligned left and right when viewed from the front, but the first and second lifting mechanisms 10A, 10B may be aligned front and rear, or the first and second lifting mechanisms 10A, 10B may be aligned diagonally (on a diagonal line of the substantially rectangular movable platen 3). In other words, the difference β, which is the height difference between the first portion 3A and the second portion 3B of the movable platen 3, is not limited to the left and right height difference within the movable platen 3, but may be the front and rear height difference or the diagonal height difference.

[0024] Fig. 3 is an enlarged cross-sectional view of the connecting structure 20 shown in Fig. 1. A plurality of (e.g., eight) connecting devices (20A, 20B, ...) are attached to the first lifting mechanism 10A. Similarly, a plurality of (e.g., eight) connecting devices (20A, 20B, ...) are attached to the other lifting mechanisms 10B, 10C, 10D. These multiple connecting devices (20A, 20B, ...) are collectively referred to as the connecting structure 20.

[0025] 3, the ring 13 of the first lifting mechanism 10A is provided with a cylindrical body 131, flange portions 132 radially protruding from the upper end of the body 131, and through holes 133 penetrating the flange portions 132 in the extending direction (up-down direction) of the tie bars 4. Each of the connectors 20A, 20B, ... is, for example, a fastening screw, and has a threaded portion 23 formed with a male thread that screws into the movable platen 3, a cylindrical portion 22 formed in a columnar shape with approximately the same diameter as the through hole 133 of the ring 13, and a head portion 21 formed with a larger diameter than the through hole 133.

[0026] The surface of the cylindrical portion 22 is a smooth columnar shape without any irregularities, and is in sliding contact with the inner peripheral surface of a through hole 133 of approximately the same diameter. There is a gap of length α between the seat surface of the head 21 of the connectors 20A, 20B and the lower surface of the flange portion 132 of the ring 13. In other words, the connectors 20A, 20B, ... and the flange portion 132 form a free shank structure having a range of motion of a predetermined value α.

[0027] As a result, even if the first lifting mechanism 10A raises or lowers the position of the movable platen 3 within the range of the predetermined value α, the flange portion 132 will not come into contact with the head 21 of the connector 20A. On the other hand, even if an attempt is made to move the first lifting mechanism 10A beyond the predetermined value α, the head 21 of the connector 20A will come into contact with the flange portion 132, restricting further movement of the movable platen 3.

[0028] According to the mold clamping device 1 of this embodiment configured as described above, even if the difference β exceeds the predetermined value α, the connecting structure 20 restricts the movement of the movable platen 3. Therefore, it is possible to prevent the movable platen 3 from tilting excessively and damaging the tie bars 4. Even if the difference β is at its maximum within the range of the predetermined value α, the movable platen 3 can slide smoothly on the surface of the tie bars 4, so the mold clamping device 1 can be used without damaging the tie bars 4.

[0029] The nut 12 of the ball screw not only moves linearly in the extension direction of the shaft portion 11, but also receives a rotational load that tends to rotate around the shaft portion 11 due to friction with the shaft portion 11. In this embodiment, since a plurality of connectors 20A, 20B, ... are provided around the shaft of the first lifting mechanism 10A, such a rotational load can be dispersed.

[0030] The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangements, materials, conditions, shapes, sizes, etc., are not limited to those shown as examples and can be changed as appropriate. In addition, configurations shown in different embodiments can be replaced or combined in terms of regions.

[0031] For example, the stopper that restricts the movement of the movable platen 3 is not limited to the example shown in Fig. 3. It may be a hook or the like that engages when the height difference β between the first portion 3A and the second portion 3B of the movable platen 3 reaches a predetermined value α. [Explanation of symbols]

[0032] 1... clamping device, 2... fixed platen, 3... movable platen, 3A, 3B, 3C, 3D... first to fourth parts, 4... tie bar, 10... drive mechanism, 10A, 10B, 10C, 10D... first to fourth lifting mechanisms, 11... shaft portion, 12... nut, 13... ring, 14... clamping screw, 15... motor, 20... connecting structure, 20A, 20B, ... connector, 21... head, 22... cylindrical portion, 23... threaded portion, 131... body, 132... flange portion, 133... through hole, α... specified value, β... difference.

Claims

1. (delete)

2. (delete)

3. a movable platen that moves along the tie bars; A plurality of lifting mechanisms including a first lifting mechanism and a second lifting mechanism are provided, a drive mechanism configured to be able to set a difference such that a first portion of the movable platen corresponding to the first lifting mechanism is at a higher or lower position than a second portion of the movable platen corresponding to the second lifting mechanism, and which moves the movable platen; a coupling structure that couples the drive mechanism to the movable platen, the connecting structure is configured as a stopper that restricts movement of the movable platen so that the difference does not exceed a predetermined value, the coupling structure includes a plurality of couplings attached to the first lifting mechanism; Each of the plurality of connectors constitutes a free shank structure having the predetermined range of motion, Mold clamping device.

4. The movable platen is configured to be able to smoothly slide on the tie bar surface when the difference is equal to the predetermined value. The mold clamping device according to claim 3.

5. The drive mechanism includes four lifting mechanisms. The mold clamping device according to claim 3 or 4.

Images