JPH04347613A - Setting method for mold clamping force in toggle type injection molding machine - Google Patents

Abstract

PURPOSE:To enable setting mold clamping force by using a mold assembly having a form wherein a gap is formed between molds when force for separating the molds acts and external force does not act on a toggle type injection molding machine. CONSTITUTION:Mold closing is performed by remarkably smaller force than mold clamping force. The rate of transfer of a movable platen for generating the prescribed mold clamping force is calculated. After a mold is opened from the position of the piston rod of a mold clamping cylinder at this time, the whole toggle mechanism is moved by the rate of transfer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamping force setting method for a toggle injection molding machine.

0002

2. Description of the Related Art A general toggle type injection molding machine is shown in FIGS. 6 and 7. FIG. 6 shows the fixed mold 106 and the movable mold 1.
08 is fixed to the fixed platen 102 and the movable platen 104, and the mold is closed, before setting the mold clamping force. That is, the molds (not shown) that had been attached to the fixed platen 102 and the movable platen 104 are loosened, and low-pressure oil pressure is supplied to the oil chamber on the piston rod 114 side of the mold clamping cylinder 110 to close the piston. 112 to the left in FIG. 6, the movable platen 104 is positioned at a mold opening position to the left of the illustrated position. The used mold is carried out, and a fixed side die 106 and a movable side die 108 having a larger total dimension in the thickness direction are newly carried in, and the oil chamber on the piston head side of the mold clamping cylinder 110 is installed. By supplying low pressure hydraulic pressure to move the piston 112 to the illustrated position, the movable platen 104 is positioned at the mold closing position. As a result, the fixed side mold 106 and the movable side mold 10
8 are located at the positions shown in the figure, these are attached to the fixed plate 102.
and fixed to the movable platen 104 with bolts (not shown). The mold clamping force setting method for a conventional toggle injection molding machine was performed as follows. First, the mold is opened from the state shown in FIG. 6, and the nut drive motor 116 shown in FIG. (If the mold thickness becomes larger than before) Rotate in the loosening direction. As a result, the entire toggle mechanism moves to the left (backward) in FIG. 6, and the bends of the toggle links 126 and 128 are extended and become nearly straight. The amount of movement of the entire toggle mechanism is detected by a potentiometer 132 connected to the shaft of the worm 120. The mold is closed again under low pressure, and the toggle links 126 and 128 are fully extended, and both molds 106 and 10
Check whether there is a predetermined gap between 8 and 122.
Repeat rotation and mold closing. When the above state is reached, the nut drive motor 116 is driven in the opposite direction in this state to advance the entire toggle mechanism until both the molds 106 and 108 come into close contact. After the molds 106 and 108 are in close contact with each other, the load on the nut drive motor 116 increases, so this is detected and the nut drive motor 116 is stopped. As a result, the zero point of the mold clamping force setting is detected. In this state, the toggle links 126 and 128 are fully extended, so even if high pressure oil is supplied to the oil chamber on the piston head side of the mold clamping cylinder 110, the movable platen 104 will not move forward any further. Therefore, both molds 106 and 108 are in close contact (
(the mold is closed) and no mold clamping force is generated. Next, the mold is opened once again, and the tie bar nut 122 is rotated to move the entire toggle mechanism forward by a predetermined distance. The mold clamping force is set by the above steps. The size of this predetermined dimension is the deformation dimension of each part of the mold clamping device necessary to generate a predetermined mold clamping force (elongation of tie bars 130, contraction of toggle links 126, 128, etc., deflection, etc.), and can be determined in advance by actual measurement or calculation. Thereby, the mold clamping force can be set to a predetermined magnitude.

0003

[Problems to be Solved by the Invention] However, in the conventional mold clamping force setting method for the toggle type injection molding machine as described above, the toggle links 126 and 128 are fully extended, and the gap between the two molds 106 and 108 is There was a problem in that it took a lot of time to repeat the work until the parts were positioned so that there was a predetermined gap between them. Therefore, the special public official 1986-359
A method such as that shown in Publication No. 24 has come to be used. The mold clamping force setting method for the toggle type injection molding machine shown here is as shown in FIG. The entire toggle mechanism is moved backward by rotating the tie bar nut 122 while continuing the mold closing operation by supplying low pressure oil to the oil chamber on the piston head side of the mold. As a result, the toggle link 1 is
26 and 128 gradually elongate. At this time, as the piston rod 114 moves forward, the rack 136 and pinion 1
A measured mold clamping force signal obtained by operating a mold clamping force signal generating device 140 such as a potentiometer is output to the control device 146 via 38 . The control device 146 compares the input measured mold clamping force signal with a preset mold clamping force signal, and when both signals match, stops the rotation of the tie bar nut 122 and the supply of low pressure oil. . The mold clamping force has been set using the above steps. Thereby, the mold clamping force can be set in a short time without repeating operations. However, with any of the above mold clamping force setting methods, it is impossible to set the mold clamping force when using a so-called three-piece spring-equipped mold (mold assembly) as shown in FIG. 9, for example. There is a problem. That is, the three-piece spring-equipped mold has an intermediate mold 142 between the fixed mold 106 and the movable mold 108, and the fixed mold 106 and the intermediate mold 142 are arranged so that they are not mutually connected. A plurality of (usually four) compression springs 144 are arranged to apply a pulling force. In the three-piece mold with spring, the sprue and runner formed between the stationary mold 106 and the intermediate mold 142 are connected to the intermediate mold 142 and the movable mold 108.
The molded product can be reliably separated from the molded product that is molded between the
Sprues and runners can be separated from each mold, so they have been increasingly used in recent years, but when the molds are brought into close contact, the force of the compression spring 144 can weigh several hundred kilograms per piece. It's big. Therefore, in the conventional mold clamping force setting method, three molds 106, 142 and 108
The nut drive motor 116 may stop due to the contact completion signal being output before the two are in contact with each other.
In the case of the method shown in Publication No. 35924, problems such as the low pressure applied to the mold clamping cylinder 110 when setting the mold clamping force are insufficient to bring the molds into close contact with each other occur, and eventually, This means that a predetermined mold clamping force cannot be set. When the three molds 106, 142, and 108 are brought into close contact with each other against the force of the compression spring 144, it is also possible to output a signal indicating that the contact is complete.
Along with this, it becomes necessary to rotate the tie bar nut 122 under a large load, so not only is it necessary to replace the nut drive motor 116 and gear mechanism 118 with larger ones, but also the tie bar 130 and tie bar nut 122 must be rotated. There is a risk that galling or seizure may occur in the threaded portion of the nut 122. In addition, in the case of the method shown in Japanese Patent Publication No. 61-35924, if the pressure applied to the mold clamping cylinder 110 when setting the mold clamping force is set to high pressure, the three molds 106, 1
42 and 108 can be brought into close contact with each other, but in this case as well, it is necessary to replace the nut drive motor 116 and gear mechanism 118 with larger ones. There is a risk of galling or seizure. The present invention aims to solve these problems.

0004

[Means for Solving the Problems] The present invention utilizes the characteristics of the toggle mechanism to transmit force, and utilizes the magnification rate (hereinafter referred to as " The above-mentioned problem is solved by bringing a mold assembly including a spring etc. into close contact with a small force in the range of 1.5 times or less (referred to as "toggle expansion power factor"). In a general toggle type mold clamping device, as shown in Figure 4, the movable platen moves as the piston rod of the mold clamping cylinder moves, but the amount of movement of the movable plate increases as the piston rod movement increases. The ratio decreases rapidly near the maximum position of piston rod travel. On the other hand, the toggle expansion power factor is almost inversely proportional to the rate at which the moving amount of the movable plate increases, and increases rapidly near the maximum position of the piston rod moving amount. Mold touch point when the generated mold clamping force is set to be maximum (
The amount of movement of the movable plate in a state in which the molds are in contact with each other (assuming there is no force to separate the molds) varies depending on the toggle mechanism and the dimensions of each part, but in general, for small machines, it is 1 to 5 mm from the maximum position. In the case of large machines, it is 5 to 10 mm smaller than the maximum position. The toggle expansion power factor at that position is relatively large, around 5 times. However, the amount of movement of the movable plate is 5 to 10 times further than the above mold touch point.
The toggle magnification power factor at a position where the mold is open by 5 to 10 mm (if a normal mold without a built-in spring or the like is used) is as small as 0.5 to 1.5 times. If high pressure oil is supplied to the piston head side oil chamber of the mold clamping cylinder in a region where this toggle expansion power factor is 1.5 times or less,
Although the mold closing force is large enough to bring the three spring-equipped molds into close contact, it is not large enough to overcome the tensile reaction force of the tie bars and complete the mold clamping process. In the present invention, the mold clamping force is set using this mold closing operation. In other words, in the mold clamping force setting method of the toggle type injection molding machine of the present invention, a force is applied to separate the molds by a compression spring, etc., and when no external force is applied to each mold, there is no gap between the molds. This article deals with the method of setting the mold clamping force of a toggle type injection molding machine when replacing a mold assembly that causes Data on the amount of movement, the amount of movement of the movable platen at the mold touch point (the state in which the molds are in contact with each other assuming there is no force to separate the molds), and the generated mold clamping force after the mold clamping operation is completed. When the movable platen is moved forward without the mold assembly attached, the distance between the movable platen and the fixed platen is larger than the mold assembly adhesion thickness dimension by the preset value. After adjusting the mold thickness so that it is reduced by a certain amount, the mold assembly is attached and the mold is closed under high pressure to increase the toggle expansion power factor (expansion of the force transmitted from the mold clamping cylinder to the movable platen via the toggle mechanism). The mold assembly is brought into close contact with a small force within the range of 1.5 times or less, and the amount of movement of the piston rod of the mold clamping cylinder at this time is detected, and based on the above data, it is determined that the mold assembly is not attached. Calculate the amount of movement of the movable plate under the assumption, find the difference between the calculated amount of movement of the movable plate and the amount of movement of the movable plate at the mold touch point corresponding to the set mold clamping force, and then toggle by the above difference after opening the mold. The entire mechanism is moved.

[0005]

[Operation] Data on the amount of movement of the movable plate relative to the amount of movement of the piston rod of the mold clamping cylinder from the reference position, and the relationship between the amount of movement of the movable plate at the mold touch point and the mold clamping force generated after the mold clamping operation is completed. Remember the data. The mold thickness is adjusted to be smaller than the mold thickness by a predetermined amount, the mold is opened, and the mold assembly is carried between the fixed platen and the movable platen. Next, the mold is closed under low pressure, and the fixed side mold and movable side mold are attached to the fixed platen and movable platen, respectively.
The molds are closed using high pressure, and the molds are brought into close contact against the force of compression springs built into the molds. In this state, the amount of movement of the piston rod of the mold clamping cylinder is detected. A movable platen movement amount corresponding to the piston rod movement amount detected from the above data is calculated. Furthermore, the amount of movement of the movable platen at the touch point of the mold corresponding to the set mold clamping force is calculated from the relationship data between the amount of movement of the movable platen at the touch point of the mold and the generated mold clamping force obtained in advance. The difference in the amount of movement of the two movable plates becomes the amount of movement of the entire toggle mechanism required to generate the set mold clamping force. After opening the mold, the entire toggle mechanism is moved by the above difference. This means that the mold clamping force has been set. During a molding operation, the mold assembly is clamped with a set mold clamping force. This allows the molded product to be injection molded. According to the method of the present invention, even in a mold assembly in which a force is applied to separate the molds and a gap occurs between the molds when no external force is applied to the molds, the toggle mechanism The mold clamping force can be set without increasing the size of the mechanism that drives the mold.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 show a toggle injection molding machine for carrying out the method of the present invention. A fixed platen 12 is fixed on the base 10. A movable platen 14 is arranged opposite to the fixed platen 12. In Figure 1 of the movable platen 14, the mold clamping housing 16 is on the left side.
is located. Four tie bars 18 are arranged passing through the fixed platen 12, the movable platen 14, and the mold clamping housing 16 (only two tie bars 18 are visible in FIG. 1). Threaded portions 18a are formed at both ends of the tie bar 18, and tie bar nuts 20 and 22 are screwed into these. In the figure, a worm wheel portion 22a that engages with a worm 66, which will be described later, is formed on the outer periphery of the tie bar nut 22 on the left side (see FIG. 3). A fixed mold 24 is fixed to the fixed platen 12, and a movable mold 26 is fixed to the movable plate 14. An intermediate mold 28 is arranged between the fixed mold 24 and the movable mold 26. Four guide rods 30 are fixed to the surface of the stationary mold 24 facing the intermediate mold 28 (only two guide rods 30 are visible in FIG. 1). The guide rod 30 is fitted into the intermediate mold 28 and can guide the movement of the intermediate mold 28 in the axial direction. A compression spring 32 is disposed between the stationary mold 24 and the intermediate mold 28 so as to separate them from each other. The same number of compression springs 32 as the guide rods 30 are provided. A mold assembly is constituted by the stationary mold 24, the compression spring 32, the intermediate mold 28, the movable mold 26, and the like. 4 on the surface opposite to the mold mounting surface of the movable platen 14.
Two link fittings 34 are each fixed (note that only two are visible in FIG. 1). Link fitting 34
are connected to one end of a long link 36, respectively. One end of a short link 38 is connected to the other end of the long link 36, respectively. The other ends of the short links 38 are respectively connected to link fittings 40 on the mold clamping housing 16 side. The link fixtures 40 are each fixed to the mold clamping housing 16. One end of a cross link 42 is connected to the mutual connection portion of the long link 36 and the short link 38, respectively. The other end of the cross link 42 is a cross head 44
are connected to the outer periphery of each. Mold clamping housing 16
A mold clamping cylinder 48 is fixed to the surface opposite to the surface on which the link fixture 40 is arranged. Mold clamping cylinder 4
8 piston rods 52 pass through the mold clamping housing 16, and their ends are fixed to the crosshead 44. Long link 36, short link 38, cross link 4
2. A toggle mechanism 46 is constituted by a crosshead 44, a mold clamping cylinder 48, and the like. By applying hydraulic pressure to either the piston head side oil chamber or the piston rod side oil chamber of the mold clamping cylinder 48, the piston rod 5
2 can be extended or retracted. This allows the toggle mechanism 46 to expand and contract. That is, it is possible to perform a mold closing/clamping operation or a mold opening operation. A first rack 54 is fixed to the end of the piston rod 52. One end of a first support member 58 is fixed to the mold clamping housing 16 . A first pinion 56 that engages with the first rack 54 is rotatably supported at the other end of the first support member 58 . The first support member 58 includes a rotating first
A potentiometer 60 is also attached. The rotation axis of this can rotate integrally with the axis of the first pinion 56. The first potentiometer 60 is connected to the piston rod 52
The stroke can be detected and output as a stroke signal to a comparison calculator 86, which will be described later. The first rack 54, the first pinion 56, the first potentiometer 60, and the like constitute piston rod movement amount detection means. As shown in FIG. 3, a nut drive motor 62 is attached to the mold clamping housing 16. Nut drive motor 6
A gear 64 is fixed to the second shaft. Two worms 66 are rotatably supported by the mold clamping housing 16, and a gear 68 is fixed to one end of each worm. The worms 66 are engaged with worm wheel portions 22a on the outer periphery of the tie bar nuts 22, respectively. The gear 64 is meshed with two gears 68, respectively. By driving the nut drive motor 62, the gear 64
, the tie bar nut 2 via the gear 68 and the worm 66
2 can be rotated respectively. That is, the nut drive motor 62 can rotate the four tie bar nuts 22 while synchronizing them. As a result, the entire toggle mechanism including the mold clamping housing 16, the toggle mechanism 46, the movable platen 14, etc. can be moved in the left-right direction in the figure. A second rack 70 is fixed to the surface of the mold clamping housing 16 to which the mold clamping cylinder 48 is fixed. One end of an "L"-shaped second support member 72 is fixed to the base 10. A second pinion 74 is rotatably supported at the other end of the second support member 72 . The second pinion 74 is engaged with the second rack 70. A rotary second potentiometer 76 is also attached to the second support member 72 . The rotation axis of this can rotate integrally with the axis of the second pinion 74. The second potentiometer 76 can output the amount of movement of the mold clamping housing 16 with respect to the base 10 (fixed part). The second rack 70, the second pinion 74, the second potentiometer 76, and the like constitute a mold clamping housing movement amount detection means. The control panel 78 of the injection molding machine includes a mold thickness setting device 80, a mold clamping force setting device 82, a memory device 84, a comparator 86, a control output device 88, a mold thickness adjustment start push button 90, and a mold clamping force. A setting start push button 92 and the like are arranged. The mold thickness setting device 80 can set the thickness dimension of the mold. The mold clamping force setting device 82 includes
It is possible to set the required mold clamping force. In the memory device 84,
It is possible to store each data described later in advance. The comparison calculator 86 is connected to the second potentiometer 7
The stroke signal from the first potentiometer 60 and the mold thickness signal from the mold thickness setter 80 are compared and calculated, and a mold thickness adjustment end signal is output at the mold closing position. Converting the set mold clamping force signal from the clamping force setter 82 into movable platen movement amounts based on the data from the memory 84, and outputting a mold clamping force setting end signal when the two match. is possible. The control output device 88 inputs each of the above signals to control the mold clamping cylinder 48.
And a signal for stopping the nut drive motor 62 can be output. Next, the operation of this embodiment will be explained. The storage device 84 stores in advance the amount of movement of the movable plate relative to the amount of movement of the piston rod 52 of the mold clamping cylinder 48 from the reference position (for example, the most retracted position of the piston rod 52) shown in FIG. Data such as the relationship between the moving amount of the movable platen at the indicated mold touch point and the mold clamping force generated after the mold clamping operation is completed are stored. The data on the amount of movement of the movable plate relative to the amount of movement of the piston rod may be obtained from a relational calculation formula or an approximate calculation formula obtained from the geometrical positional relationship of each part of the toggle mechanism, or from a plurality of calculation formulas obtained from those calculation formulas or from actual measurements. Discontinuation point data (calculations between discontinuation points are performed by interpolation) may be used. Furthermore, since there is an almost linear relationship between the moving amount of the movable platen at the mold touch point and the mold clamping force generated after the mold clamping operation is completed, the data may be the relationship calculation formula itself, or the calculation formula or the actual mold clamping force. Multiple discontinuation point data obtained by measurement (calculations between discontinuation points are calculated using interpolation method)
But that's fine. Note that the numerical values and characteristic lines in FIG. 4 show an example. First, with the mold removed, the thickness dimension (dimension when the molds are in close contact with each other) of the compression spring-equipped mold assembly 94 to be used next is input into the mold thickness setting device 80. Further, the necessary mold clamping force is input into the mold clamping force setting device 82. Next, when the mold thickness adjustment start push button 90 is pressed, this signal is transmitted to the control device of the injection molding machine main body (not shown) via the control output device 88, and the nut drive motor 62 is driven. As a result, the tie bar nut 22 rotates via the gears 64, 68 and the worm 66, and the mold clamping housing 16 moves forward or backward. The direction and amount of movement of the mold clamping housing 16 at this time are based on the mold thickness input to the mold thickness setting device 80 and the actual mold thickness detected by the first potentiometer 60 (preset reference mold thickness). The amount of displacement with respect to the position of the mold clamping housing 16 at the time is added to the reference mold thickness and detected as the actual mold thickness.This value is compared with the actual mold thickness (hereinafter referred to as the actual mold thickness), and finally the actual mold thickness is determined. The toggle expansion power factor is 1.5 times or less when the molds are in close contact with each other by closing the mold by a preset amount than the mold thickness (an ordinary mold that does not have a built-in compression spring, etc.) This is a preset amount that varies depending on the toggle mechanism and the dimensions of the component parts, etc., and is controlled to be reduced by about 10 to 15 mm in the case of a small machine and 15 to 20 mm in the case of a large machine). Thereafter, low pressure oil is supplied to the piston rod side oil chamber of the mold clamping cylinder 48 to open the mold. This completes the mold thickness adjustment. In addition, if the above-mentioned predetermined amount is further set larger by about 5 mm, an input error of about 5 mm in the mold thickness can be tolerated, thereby increasing practicality. Next, the mold assembly 94
is carried between the fixed platen 12 and the movable platen 14 by a crane or the like, and low pressure oil is supplied to the piston head side oil chamber of the mold clamping cylinder 48. As a result, the movable mold 26 and the intermediate mold 28 come into close contact, but the intermediate mold 28 and the fixed mold 28
The gap is kept open by the force of the compression spring 32. In this state, use bolts etc. to attach the fixed side mold 24 to the fixed platen 12.
is fixed, and the movable side mold 26 is also fixed to the movable platen 14. Next, press the mold clamping force setting start push button 92. This signal is transmitted to the control device of the injection molding machine main body (not shown) via the control output device 88, and high pressure oil is supplied to the piston head side oil chamber of the mold clamping cylinder 48, and the intermediate mold 28 and fixed side mold 24 are in close contact against the force of the compression spring 32. In other words, the mold is closed. However, in this state, as shown in FIG. 4(b), the mold is touched with a small force in the range of 1.5 times or less of the toggle magnification power factor.
The mold closing force at this time is 1/20 to 1/2 of the final mold clamping force.
30, and no so-called mold clamping operation is performed. In this state, the amount of piston rod movement of the mold clamping cylinder 48 detected by the first potentiometer 60 is input to the comparator 86, and the relationship data between the amount of piston rod movement and the amount of movement of the movable plate is stored in the memory 84. compared to
Movable platen 14 corresponding to the detected piston rod movement amount
The detected movement amount is calculated. Note that the comparator 86 calculates the mold corresponding to the set mold clamping force based on the relationship data between the moving amount of the movable platen at the mold touch point and the mold clamping force generated after the mold clamping operation is completed, which is stored in the memory 84. The amount of movement of the movable platen at the touch point, that is, the reference amount of movement, is calculated in advance, and the difference between the reference amount of movement of the movable platen 14 and the detected amount of movement, that is, the mold clamping housing required to generate the set mold clamping force. The required movement amount of the entire toggle mechanism 46 including 16 is calculated. Next, after low pressure oil is supplied to the piston rod side oil chamber of the mold clamping cylinder 48 and the mold is opened, the nut drive motor 62
is driven, the tie bar nut 22 is rotated, and the entire toggle mechanism 46 is moved backward. The amount of movement at this time is detected by the second potentiometer 76 and transmitted to the comparator 86. When the above-mentioned required amount of movement is reached, a stop signal is output from the comparator 86 to the control device of the injection molding machine main body via the control output device 88, and the rotation of the nut drive motor 62 is stopped. This completes the setting of the mold clamping force. Note that the amount of overrun that occurs between when the stop signal is output and when the nut drive motor 62 stops rotating is subtracted from the required amount of movement in advance. During molding work, the molds 24, 26, and 2 are
8, the mold is clamped with a large toggle expansion power factor (usually 20 times or more), that is, with a set mold clamping force against the force of the compression spring 32. In addition, in the above description, the mold assembly 94
The three-piece mold 24, 26 and 2 have a compression spring 32 as
8, but any type that creates a gap between the molds when no external force is acting on the molds may be used. For example, a repulsive magnetic force may be applied between the molds to separate the molds. The method of the present invention can also be applied to such devices. Furthermore, although the potentiometers 60 and 76 are used in the above description, a pulse generator (encoder) or the like may also be used. Furthermore, by detecting the position of the movable platen 14 using the output signal of the potentiometer 60 and the relationship data between the piston rod movement amount and the movable platen movement amount stored in the memory device 84, mold closing and mold removal can be performed. You can also control the opening speed. In addition, if the mold clamping force setting method described above and the mold clamping force setting method shown in Japanese Patent Publication No. 61-35924 can be selected and implemented using a changeover switch, etc., the mold having the compression spring 32 and the compression The clamping force can be set for both types of molds without springs. Although it is possible to set the clamping force for a mold without a compression spring using the method of the present invention, the method disclosed in Japanese Patent Publication No. 61-35924 requires one less mold opening operation. Therefore, the setting time is short, and the setting process does not require high-pressure oil, so it is safe.

[0007]

[Effects of the Invention] As explained above, according to the present invention,
Even when using a mold assembly where a force is applied to separate the molds, the mold clamping force can be set in a short time without increasing the size of the nut drive motor or gear mechanism. be able to.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which a mold of a toggle injection molding machine for carrying out the method of the present invention is opened.

FIG. 2 is a diagram showing a state in which the mold is closed.

FIG. 3 is a diagram of the toggle injection molding machine viewed from the mold clamping cylinder side.

FIG. 4 is a diagram showing the relationship between the toggle expansion power factor and the moving amount of the movable plate with respect to the moving amount of the piston rod of the mold clamping cylinder.

FIG. 5 is a diagram showing the relationship between the moving amount of the movable platen at the mold touch point and the mold clamping force generated after the mold clamping operation is completed.

FIG. 6 is a diagram showing a conventional toggle injection molding machine.

FIG. 7 is a diagram of a conventional toggle injection molding machine viewed from the mold clamping cylinder side.

FIG. 8 is a diagram showing another conventional toggle type injection molding machine.

FIG. 9 is a diagram showing a three-piece mold (mold assembly) with a compression spring.

[Explanation of symbols]

14 Movable plate 24 Fixed side mold 26 Movable side mold 28 Intermediate mold 32 Compression spring 46 Toggle mechanism 94 Mold assembly

Claims (1)

[Claims] [Claim 1] When replacing a mold assembly in which a force is applied to separate the molds by a compression spring or the like, and a gap is created between the molds when no external force is applied to each mold. In the mold clamping force setting method for a toggle type injection molding machine, data on the amount of movement of the movable platen relative to the amount of movement of the piston rod of the mold clamping cylinder from the reference position, and the mold touch point (the force that separates the molds from each other) are prepared in advance. Data on the relationship between the moving amount of the movable platen and the mold clamping force generated after the mold clamping operation is completed at the position where each mold is in contact with each other is stored, assuming that the mold assembly is not installed. After adjusting the mold thickness so that when the movable platen is moved forward, the distance between the movable platen and the fixed platen is smaller than the mold assembly contact thickness dimension by a preset amount, the mold assembly is installed. Then, by closing the mold with high pressure, the mold assembly is completed with a small force within the range of 1.5 times or less of the toggle expansion power factor (the magnification rate of the force transmitted from the mold clamping cylinder to the movable platen via the toggle mechanism). The amount of movement of the piston rod of the mold clamping cylinder at this time is detected, the amount of movement of the movable platen is calculated based on the above data assuming that the mold assembly is not attached, and this calculated amount of movement of the movable platen is Mold clamping for a toggle type injection molding machine, characterized in that the difference between the amount of movement and the amount of movement of the movable plate at the mold touch point corresponding to the set mold clamping force is determined, and the entire toggle mechanism is moved by the above difference after the mold is opened. How to set force.