JP2796759B2 - Toggle mold clamping method and apparatus for injection molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toggle mold clamping method for an injection molding machine and an improvement of the apparatus.

(Prior art and its problems) In a die casting machine or a resin injection molding machine using a toggle device, additional tightening is performed to resist the injection pressure at the time of injection. First, attach the mold to be used, with the toggle extended, until the parting surface of the mold matches
Advance the entire toggle device. Next, the mold is slightly opened to loosen the toggle, and the tie nut on the cylinder plate side is tightened by a predetermined amount in accordance with the set mold clamping force (re-tightening).
As a result, when the toggle is extended and the toggle arm exceeds the point of highest resistance (dead point) and extends straight, the tie bar elastically expands like slipping, and a large tightening amount is applied to the parting surface of the mold. give.

At this time, when the dies (2) and (5) are larger than the die plates (1) and (4) as shown in FIG. 3 (a), the die clamping force is applied to the tie bars (3). And the molds (2) and (5) as shown in FIG. 3 (b).
When the die is small, the die plates (1) and (4) bend and the required mold clamping force (F) cannot be obtained. The clamping force (F) does not match the actual clamping force, and the clamping force (F) becomes excessively large, damaging the tie bars (3) ... or conversely due to insufficient clamping force (F). There is a drawback that a problem such as generation of burrs of a molded product has occurred.

(Object of the Invention) An object of the present invention is to adjust the amount of tightening of the tie nut (the amount of additional tightening) in consideration of the shape of the die with respect to the die plate, and there is a difference in the shape of the die with respect to the die plate. It is an object of the present invention to provide a toggle mold clamping method and an apparatus for an injection molding machine that can always exert a constant mold clamping force.

(Means for Solving the Problem) According to the method of the present invention, a fixed die plate (1) and a fixed die plate (1) are provided in order to solve the above problems.
, A movable die plate (4) moving along a tie bar (3), a movable die (5) mounted on the movable die plate (4), and a movable die. In an injection molding machine (A) equipped with a toggle device (6) for reciprocating the plate (5) and clamping the die, a die plate (1) (4) that changes depending on the shape of the mold (2) (5). ) Is calculated, and the mold clamping force (F) is calculated according to the first expression shown in claim (1).
Is attached to the tie bar (3), and the tie nuts (7), which are attached to the tie bars (3) to move the toggle device (6) forward and backward, to regulate the re-tightening amount (Δl) by the movable die plate (4), to the calculated value. Screw and retreat together.

 It employs technical means.

Further, in order to carry out the above method, in the toggle mold clamping device (6) according to claim (2), a fixed die plate (1) and a fixed die (2) mounted on the fixed die plate (1).
And a moving die plate (4) moving along the tie bar (3) ... and a moving die (2) mounted on the moving die plate (4).
A toggle device (6) for reciprocating the movable die plate (4) and performing a mold clamping operation; and a deflection amount of the die plates (1) (4) which changes depending on the shapes of the dies (2) and (5). The resulting toggle efficiency "f
(Η)], a calculating device for calculating the clamping force (F) according to the first expression of claim (1), and a tie bar (3)... To move the toggle device (6) forward and backward. And a driving device (10) for screwing and retreating the tie nuts (7) in accordance with the calculated values. Have been.

(Operation) When tightening the tie nuts (7) for additional tightening, input the thickness (D) and size of the molds (2) and (5) and the mold clamping force (F) to the arithmetic unit. For example, an additional tightening amount (Δl) sufficient to apply a force corresponding to the set mold clamping force (F) in consideration of the sizes of the dies (2) and (5) is calculated according to the first equation. The matching tie nuts (7) are tightened. As a result, mold clamping is performed with substantially the same force as the set mold clamping force (F).

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. The injection molding machine (A) includes a gantry (8) and a fixed die plate (1).
, A fixed die (2) mounted on the fixed die plate (1), a moving die plate (4) moving along the tie bars (3),..., And a moving die mounted on the moving die plate (4). It comprises a mold (5), a toggle device (6) for moving the movable die plate (4), a hydraulic mechanism (not shown), and a control device (not shown). The tie bars (3) are provided at four corners of the fixed die plate (1) and the tail stock (11), and the movable die plate (4) is disposed on the tie bars (3) so as to be able to reciprocate freely. . A fixed mold (2) and a movable mold (5) are mounted on the opposed surfaces of the fixed die plate (1) and the movable die plate (4). The toggle device (6) includes a toggle arm (12) attached to the tail stock (11), a toggle link B (13) pivotally attached to the toggle arm (12),
A toggle link A (14) pivotally connected between the toggle link B (13) and the movable die plate (4),
5) The mold clamping cylinder (17) and the mold clamping cylinder (1
7) The crosshead (15) mounted on the cylinder rod (17a) and the crosshead (15) and the toggle link B
(13) and a toggle link C (16) pivotally mounted between them. The toggle device (6) is a movable die plate (4)
There are a vertical type having a toggle link A (14) pivotally attached to the upper and lower ends, and a horizontal type mounted on both sides of a movable die plate (4). The illustrated embodiment is a vertical type. FIG. 4 is an arrow view from the tailstock (11) side. A main gear (18) is rotatably mounted at the center of the tailstock (11).
A driven gear motor (19) and a driven gear (20) of a tie nut (7) attached to the end of the tie bar (3).
Are engaged with the main gear (18). One of the tie nuts (7) is provided with a rotation angle detecting device (21) for determining the rotation angle of the tie nuts (7).

Then, the fixed and movable dies (2) and (5) are attached to the fixed and movable die plates (1) and (4) to be used, respectively, and both molds (2) and (5) are extended with the toggle device (6) extended. The entire toggle device (6) is advanced to a position where the parting surface of (1) matches. Next, after slightly opening the mold, loosening the toggle device (6), the set mold clamping force (F)
Tie nut (7) on tailstock (11) side according to
... is tightened by a predetermined amount. The amount of retightening (Δl) depends on the thickness (D) of the dies (2) and (5) and the
A table containing data of the sizes of the dies (2) and (5) for (4) is created and stored in the storage circuit of the arithmetic unit, and when the clamping force (F) is set, the clamping force ( F),
By inputting the mold thickness (D) and the size of the molds (2) and (5) from the input device to the computing device, the values are determined as values sufficient to provide the necessary mold clamping force. FIG. 6 is an example of a table for calculating a mold clamping force (F). In general, the die plates (1) and (4) are bent as the dimensions of a die to be mounted are increased. The amount becomes small, and the toggle efficiency (η) in FIG. 6 gradually approaches “1”. A general expression representing the curve of the toggle efficiency (η) is represented by “f
(Η)]. The general formula “f (η)” is determined by conducting experiments using various molds (2) and (5). or,
In the present embodiment, there are four tie bars (3), the cross-sectional area of which is "A", the Young's modulus of tie bars (3) ... is "E", and the amount of elongation of tie bars (3) (ie, the amount of tightening). To “Δl”,
Assuming that the effective length between the tie nuts (7) and (7 ') of the tie bars (3) ... is "L", a so-called set clamping force "F" including a necessary additional tightening amount is expressed by the following first formula. Is done.

F = 4 · A · E · (Δl / L) · f (η) Formula 1 In the above formula 1, if the total thickness (D) of the molds (2) and (5) is input to the arithmetic unit. , Tie bar (3) which is a known value, length (L), both die plates (1)
From the thickness of (4), the thickness of the tailstock (11) and the length of the toggle device (6) at the time of extension, etc., the tie bar (3) ...
"L" is required for the effective length between the tie nuts (7) and (7 '). Also, the size of the molds (2) and (5) is the vertical dimension in the case of the vertical toggle mechanism shown in FIG. 1, and the horizontal dimension in the case of the horizontal toggle mechanism. When｝ is input to the arithmetic unit, the function (f (η)) of the toggle efficiency that changes depending on the size of the molds (2) and (5) with respect to the die plates (1) and (4) is obtained from the mold (2) ( The toggle efficiency of 5) is calculated. This function “f (η)” is usually stored in the storage device in advance, and the toggle efficiency is calculated as soon as the size of the molds (2) and (5) is input. Further, if the set mold clamping force "F" is input to the arithmetic unit, the cross-sectional area "A" of the tie bar (3)... And the Young's modulus "E" of the tie bar (3). , Retightening amount (Δ
l) is required. When the elongation “Δl” of the tie bars (3)... Taking into account the sizes of the dies (2) and (5) is calculated in this way, the gear motor (19) rotates and the main gear (18) rotates. Then, the driven gears (20) attached to the individual tie nuts (3) are rotated. The rotation amount of the tie nut (3) is sequentially detected by the rotation angle detection device (21), and is equal to the elongation amount “Δl” (3).
… Is tightened. When the tightening of the tie nuts (3) is completed, the toggle device (6) is extended again to perform mold clamping, and then the operation following injection molding to the mold cavity is performed as before.

(Effects) As described above, the method of the present invention calculates the toggle efficiency resulting from the amount of deflection of the die plate that changes depending on the shape of the mold, and calculates the mold clamping force according to the first equation. Since the amount of bending of the plate can also be taken into account, the mold can be clamped with a force that matches the set clamping force regardless of the size of the mold, and the clamping force is set as in the past. Despite the fact that the change in toggle efficiency due to the size of the mold was not taken into account in spite of the fact that excessive mold clamping force exceeding the set mold clamping force was applied, the tie bar was damaged, and conversely, There is an advantage that the molding does not reach the mold and the mold clamping force at the time of injection is insufficient, so that burrs do not occur on the molded product.

In addition, since the present device has a configuration as described in claim (2), the tie nut can be advanced and retracted in accordance with the operation value calculated by the first expression, and the size of the mold can be reduced. The mold can always be clamped with the set mold clamping force.

[Brief description of the drawings]

Fig. 1 is a front view of one embodiment of the present invention, Figs. 2 (a) to 2 (c) are front views showing a mold clamping procedure of the present invention, Figs. 3 (a) and 3 (b) are drawings of the present invention. FIG. 4 is a front view schematically showing a change in the amount of deflection of the die plate due to the difference in the size of the mold. FIG. 4 is a side view of the device of the present invention viewed from the tailstock side. FIG. FIG. 6 is an enlarged view showing a meshing portion of the driven gear of the tie nut. FIG. 6 is a graph showing a change in toggle efficiency in relation to a mold size and a die plate. (A) Injection molding machine (F) Mold clamping force (or additional clamping force) (1) Fixed die plate (2) Fixed mold (3) Tie bar (4) … Moving die plate (5)… Moving mold, (6)… Toggle device (7)… Tie nut, (10)… Drive device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B22D 17/26 B29C 33 / 22,45 / 66

Claims (2)

(57) [Claims] 1. A fixed die plate, a fixed die mounted on the fixed die plate, a movable die plate moving along a tie bar, a movable die mounted on the movable die plate, and moving the movable die plate. In the injection molding machine equipped with a toggle device to calculate the toggle efficiency due to the amount of deflection of the die plate that changes according to the shape of the mold, calculate the amount of tie bar deflection, that is, the amount of tightening according to the following first formula, Attached to the tie bar, advance the toggle device
A toggle mold clamping method for an injection molding machine, characterized in that a tie nut for restricting the amount of retightening by a movable die plate by retreating is advanced and retracted in accordance with the calculated value. F = 4 · A · E · (/ l / L) · f (η)... First equation F: Mold clamping force A: Tie bar cross-sectional area E: Tie bar Young's modulus Δl: Tie bar flexure amount, ie, additional tightening Quantity L: Effective length between tie nuts of tie bar f (η): Toggle efficiency 2. A fixed die plate, a fixed die mounted on the fixed die plate, a movable die plate moving along a tie bar, a movable die mounted on the movable die plate, and reciprocating between the movable die plate. A toggle device that moves and clamps the mold, and calculates a toggle efficiency caused by a flexure amount of the die plate that changes according to a shape of the mold, and calculates a flexure amount of the tie bar, that is, a tightening amount according to the first expression of claim (1). And a tie nut attached to the tie bar to regulate the amount of retightening by the movable die plate by moving the toggle device forward and backward, and a drive device for screwing and retracting the tie nut in accordance with the calculated value A toggle mold clamping device for an injection molding machine, characterized in that: