Type-based method

Abstract

To provide a mold clamping device which can stably provide a suitable clamping force.SOLUTION: In a vertical injection metallic molding machine (1), a stationary platen (9) is provided with a rotary table (15) comprising a plurality of lower side metallic molds (18), and a clamping-target lower side metallic mold (18) can be therefore switched to the upper side metallic mold (17) provided in an upper movable platen (10). The upper movable platen (10) is provided with a distance sensor (37) detecting the thickness of the clamping target lower side metallic mold (18) that is the lower side metallic mold thickness. A control device (4) determines a metallic mold clamp crosshead position on the basis of the detected lower side metallic mold thickness and generates a metallic mold clamping force by driving the crosshead (20) of a toggle mechanism (14) to a position where the crosshead position is determined.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a mold clamping device in that is opened and closed vertically by a toggle mechanism, and a mold clamping method. [Background Art]

[0002] A toggle-type vertical injection molding machine includes a mold clamping device that opens and closes molds in the vertical direction and an injection device. The mold clamping device includes a fixed platen fixed to a frame, an upper movable platen provided above the fixed platen, and a lower movable platen provided below the fixed platen. The upper movable platen and the lower movable platen are connected by a plurality of tie bars, and a toggle mechanism is provided between the lower movable platen and the fixed platen. A rotatable rotary table is provided on the fixed platen. An upper mold is provided on the upper movable platen, and a plurality of lower molds are provided on the rotary table. The rotary table is rotated to align one of the lower molds with the upper mold. When the toggle mechanism is driven, the upper mold and the lower mold are clamped. The injection device is provided on the upper movable platen and configured to inject an injection material into the mold.

[0003] In order to generate an appropriate clamping force in a toggle-type mold clamping device, when the upper mold and the lower mold touch each other, the crosshead of the toggle mechanism needs to be at an appropriate crosshead position, that is, a mold touch position. If the upper mold and the lower mold touch each other when the crosshead is at the mold touch position, an appropriate clamping force can be obtained when the crosshead is further driven to reach the clamping crosshead position.

[0004] To ensure the crosshead is at the mold touch position when the upper and lower molds touch, the distance between the upper movable platen and the rotary table, i.e., the mold platen distance, must be adjusted to match the mold thickness of the upper and lower molds. In a toggle-type vertical injection molding machine, as described in Patent Document 1, for example, multiple tie bars are provided with tie bar nuts at their lower ends. These tie bar nuts are rotatably housed in the lower movable platen, and the tie bars and the lower movable platen are connected via the tie bar nuts. By rotating these tie bar nuts, the effective length of the tie bars, i.e., the distance between the upper and lower movable platens, can be adjusted. By adjusting the effective length of the tie bars, the distance between the upper movable platen and the rotary table, i.e., the mold platen distance, can be adjusted, thereby adjusting the mold thickness. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-30152 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The rotary table is equipped with multiple lower dies, and each lower die is designed to align with the upper die and clamp according to the rotational position of the rotary table. However, the thickness of the multiple lower dies is not necessarily the same. This is because it is difficult to make them exactly the same in dimensions due to machining accuracy and other factors. As a result, even if the die thickness of one of the lower dies is adjusted and the appropriate clamping force is obtained for that lower die, the other lower dies with different dimensions may not be able to obtain the appropriate clamping force.

[0007] This disclosure provides a mold clamping method that can stably obtain an appropriate clamping force even when the lower mold is switched by a rotary table.

[0008] Other challenges and novel features will become apparent from the description and accompanying drawings in this specification. [Means for solving the problem]

[0009] The clamping device comprises a fixed platen, an upper movable platen, and a lower movable platen. The upper and lower movable platens are connected to multiple tie bars, and a toggle mechanism is provided between the lower movable platen and the fixed platen. An upper mold is provided on the upper movable platen, and a rotary table is rotatably mounted on the fixed platen. Multiple lower molds are provided on this rotary table. When the rotary table is rotated, one of the lower molds becomes the clamping target that aligns with the upper mold. This disclosure provides a distance sensor on the upper movable platen or the upper mold. As a preliminary step, the mold thickness is adjusted in advance based on the minimum lower mold thickness among the multiple lower molds. When the mold platen distance, which is the distance between the upper movable platen and the rotary table, reaches a specified distance, a distance sensor detects the thickness of the lower mold to be clamped, i.e., the lower mold thickness. The control device of the mold clamping device determines the position of the clamping crosshead relative to the lower mold to be clamped based on the detected lower mold thickness. During mold clamping, the crosshead of the toggle mechanism is driven to the determined clamping crosshead position to generate the clamping force. [Effects of the Invention]

[0010] This disclosure provides appropriate clamping force for multiple lower molds that are switched by a rotary table. [Brief explanation of the drawing]

[0011] [Figure 1] This is a front view of a vertical injection molding machine according to the first embodiment. [Figure 2] This is a side view showing a part of a vertical injection molding machine according to the first embodiment. [Figure 3] This is a flowchart showing the preparation work according to the first embodiment. [Figure 4] This is a flowchart showing a mold thickness adjustment method according to the first embodiment. [Figure 5] This is a flowchart showing a clamping method according to the first embodiment. [Figure 6]This flowchart shows a clamping method according to a modified example of the first embodiment. [Figure 7] This flowchart shows the preparation work related to a modified example of the first embodiment. [Figure 8] This is a flowchart showing the preparation work according to the second embodiment. [Figure 9] This is a flowchart showing a clamping method according to the second embodiment. [Modes for carrying out the invention]

[0012] The following describes specific embodiments in detail with reference to the drawings. However, the embodiments are not limited to those described below. For clarity, the following descriptions and drawings have been simplified as appropriate. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations have been omitted where necessary. Also, hatching has been omitted in some parts of the drawings to avoid clutter.

[0013] [First Embodiment] <Vertical injection molding machine> The vertical injection molding machine 1 according to the first embodiment includes, as shown in Figure 1, a clamping device 2, an injection device 3 provided on the upper part of the clamping device 2, and a control device 4 that controls these.

[0014] <Mold clamping device> The clamping device 2 includes a fixed platen 9 fixed to a bed 7, an upper movable platen 10 provided above the fixed platen 9, and a lower movable platen 11 provided inside the bed 7. In the present embodiment, the upper movable platen 10 and the lower movable platen 11 are connected by three tie bars 12, 12, .... The lower end portions of the tie bars 12, 12,... and the lower movable platen 11 are connected via a mold thickness adjusting mechanism 24, which will be described in detail later. In the clamping device 2, a toggle mechanism 14 is provided between the lower movable platen 11 and the fixed platen 9, and a rotary table 15 is provided on the fixed platen 9. The rotary table 15 is configured to rotate around one central tie bar 12 in FIG. 1. The rotary table 15 is driven by a servo motor (not shown), and the rotational position of the rotary table 15 is detected by an encoder of the servo motor.

[0015] The upper movable platen 10 is provided with one upper mold 17, and the rotary table 15 is provided with a plurality of lower molds 18, 18, two in this embodiment. However, in FIG. 1, the two lower molds 18, 18 are arranged overlappingly in the drawing, so only one is shown. On the other hand, two lower molds 18, 18 are shown in the side view of FIG. 2.

[0016] The toggle mechanism 14 includes a crosshead 20, and the crosshead 20 is driven by a drive mechanism 21. When the crosshead 20 is driven, the toggle mechanism 14 bends and extends. When the toggle mechanism 14 bends and extends, the upper mold 17 and one lower mold 18 aligned with the upper mold 17 are opened and closed.

[0017] <Mold Thickness Adjusting Mechanism> The mold thickness adjusting mechanism 24 will be described. As shown in FIG. 1, a plurality of tie bars 12, 12, ... each have an external thread formed over a predetermined length near the lower end thereof. Tie bar nuts 25, ... are provided on such external threads. The lower movable platen 11 is formed with through holes 26, ... through which the tie bars 12, 12, ... are inserted, and a part of each through hole 26 is formed as an enlarged-diameter tie bar nut accommodating hole 28, .... The tie bar nuts 25, ... are respectively placed in the tie bar nut accommodating holes 28. In this way, the tie bars 12, 12, ... and the lower movable platen 11 are connected via the tie bar nuts 25, ....

[0018] Sprockets 29, ... are fixedly attached to the tie bar nuts 25, .... Although not shown in FIG. 1, a single common chain is wound around all the sprockets 29, ... and is configured to be rotated synchronously by a drive mechanism (not shown). That is, the plurality of tie bar nuts 25, ... are configured to be rotated synchronously. The mold thickness adjusting mechanism 24 is composed of these tie bar nuts 25, ..., sprockets 29, ... and the like. When the tie bar nuts 25, ... are rotated synchronously by the drive mechanism, the effective length of the tie bars 12, 12, ..., that is, the distance between the upper movable platen 10 and the lower movable platen 11 changes.

[0019] <Injection Device> The injection device 3 is provided on the upper movable platen 10 of the mold clamping device 2. The injection device 3 includes a heating cylinder 31, a screw 32 provided in the heating cylinder 31, a screw drive mechanism 33 for driving the screw 32, and a lifting device 35 for lifting and lowering the entire injection device 3. The injection device 3 is configured to rotate the screw 32 to melt injection material, and drive the screw 32 in the axial direction to inject the injection material.

[0020] <Control Device> The control device 4 is configured to control the vertical injection molding machine 1, and controls preparatory work and a mold clamping method which will be described later.

[0021] <Distance Sensor> In the vertical injection molding machine 1 according to the first embodiment, a distance sensor 37 is provided on the upper movable platen 10, as shown in Figures 1 and 2. The distance sensor 37 comprises a laser light-emitting unit and a light-receiving unit, and is capable of measuring the distance to an object. In the vertical injection molding machine 1 according to the first embodiment, the distance sensor 37 measures the distance to the lower mold 18, which is aligned with the upper mold 17, that is, the lower mold 18 that is to be clamped. When the distance between the upper movable platen 10 and the rotary table 15, that is, the mold platen distance, is a specified distance, the mold thickness of the lower mold 18, that is, the lower mold thickness, can be calculated by measuring the distance to the lower mold 18. In other words, the lower mold thickness of the lower mold 18 that is to be clamped can be detected.

[0022] <Strain Sensor> In the vertical injection molding machine 1 according to the first embodiment, a strain sensor 39 is provided on one tie bar 12, as shown in Figures 1 and 2. The tie bar 12 stretches during mold clamping, and this stretching is detected. As a result, the tension of the tie bar 12 is calculated, and the mold clamping force is obtained.

[0023] <Preparation work> In the vertical injection molding machine 1 according to the first embodiment, two lower molds 18, 18 are provided on a rotary table 15, and by rotating the rotary table 15, the lower mold 18 that is clamped to the upper mold 17 is changed, i.e., the lower mold 18 that is the target of clamping. The thickness of the lower molds 18, 18 is not necessarily the same; in other words, they are slightly different. This results in differences in the clamping force generated during clamping. However, in the clamping method according to the first embodiment, which will be explained later, the same clamping force can be generated even if the lower mold thicknesses are different. When implementing the clamping method according to the first embodiment, it is necessary to perform the preparatory work according to the first embodiment each time the molds 17, 18, 18 are replaced. This will be explained.

[0024] The preparation work according to the first embodiment will be explained with reference to Figure 3. The control device 4 (see Figure 1) first executes step S01. That is, it drives the crosshead 20 in the mold clamping device 2 to set the mold platen distance, which is the distance between the upper movable platen 10 and the rotary table 15, to a specified distance. The mold may be left in a completely open state, in which case the specified distance will be the mold platen distance in the open state. Next, the control device 4 executes step S02. That is, it measures the distance to the lower mold 18 that is currently to be clamped using the distance sensor 37, and subtracts this from the specified distance to calculate the lower mold thickness of the lower mold 18. In other words, it measures the lower mold thickness. The control device 4 stores this lower mold thickness for the lower mold 18. At this time, it stores the rotation position of the rotary table 15 in association with this measurement.

[0025] The control device executes step S03. That is, it determines whether or not the lower mold thickness has been measured for all the lower molds 18, 18 provided on the rotary table 15. In the first embodiment, there are two lower molds 18, 18, so it determines whether or not the measurement of the lower mold thickness of both lower molds 18, 18 has been completed. Here, only the lower mold thickness of one lower mold 18 has been measured and stored, so it proceeds in the direction of NO. That is, it executes step S04. In step S04, the rotary table 15 is rotated to change the lower mold 18 to be clamped. Next, the control device 4 returns to step S02 and executes step S02. That is, it measures and stores the lower mold thickness of the currently clamped lower mold 18. Similarly, it stores the rotation position of the rotary table 15 in association with this measurement.

[0026] In step S03, if it is determined that the measurement and storage of the lower mold thickness for all lower molds 18, 18 has been completed (YES), the process proceeds to step S05. The control device 4 determines the minimum lower mold thickness from among all the stored lower mold thicknesses 18, 18. Once the lower mold thickness is determined, the process proceeds to step S06. In step S06, the control device 4 determines whether the lower mold 18 currently being clamped is the lower mold 18 with the minimum lower mold thickness. If the lower mold 18 with the minimum lower mold thickness is the one being clamped, the process proceeds to step S08. If it is not (NO), the process proceeds to step S07. In step S07, the control device 4 rotates the rotary table 15 so that the lower mold 18 with the minimum lower mold thickness becomes the one being clamped. That is, the rotary table 15 is rotated to the rotation position stored in step S02 in association with the lower mold 18 with the minimum lower mold thickness. The process proceeds to step S08.

[0027] The control device 4 executes step S08. The control device 4 has the thickness of the upper mold 17, i.e., the upper mold thickness, pre-entered. This upper mold thickness is added to the minimum lower mold thickness to calculate the total thickness of the upper mold 17 and lower mold 18, i.e., the mold thickness. After calculating the mold thickness, the process moves to step S09 to perform mold thickness adjustment. In other words, the mold thickness adjustment is performed on the lower mold 18, which has the minimum lower mold thickness.

[0028] The mold thickness adjustment method performed in the preparation work according to the first embodiment will be explained by the flowchart in Figure 4. The control device 4 executes step S11. That is, it drives the mold thickness adjustment mechanism 24 (see Figure 1) to rotate the tie bar nuts 25, ... and increases the effective length of the tie bars. In this way, the mold thickness is made slightly larger than the mold thickness calculated in step S08 (see Figure 3).

[0029] Next, step S12 is executed. That is, the control device 4 (see Figure 1) drives the crosshead 20 to the mold touch position. The crosshead 20 is then driven to the clamping crosshead position to generate clamping force. In order to obtain the desired clamping force when driven to the clamping crosshead position, the toggle mechanism 14 needs to be in an appropriate bent state when the upper mold 17 and the lower mold 18 touch. The crosshead position that results in this appropriate bent state is the mold touch position.

[0030] Step S13 is executed when the crosshead position is set to the mold touch position. That is, the tie bar nuts 25, ... (see Figure 1) are rotated to reduce the effective length of the tie bars. In other words, they are driven in the direction of reducing the mold thickness. Step S13 is completed when the touch between the upper mold 17 and the lower mold 18 is detected. The touch between the upper mold 17 and the lower mold 18 is detected by the strain sensor 39 to see if a slight clamping force is generated. Alternatively, if a servo motor is provided in the drive mechanism that rotates the tie bar nuts 25, ..., the torque of the servo motor may be monitored and used for detection. Once step S13 is completed, the mold thickness adjustment is finished. The preparation work according to the first embodiment is completed. As is clear from the above, the preparation work according to the first embodiment performs mold thickness adjustment to match the minimum lower mold thickness.

[0031] <Mold clamping method> The mold clamping method according to the first embodiment will be explained with reference to Figure 5. In the vertical injection molding machine 1 (Figure 1), the mold clamping device 2 is in the open state, and the distance between the upper movable platen 10 and the rotary table 15 is set to a specified distance. The control device 4 performs step S21 shown in Figure 5. That is, the distance sensor 37 measures the lower mold thickness of the lower mold 18 that is to be clamped.

[0032] Next, the control device 4 executes step S22 to determine the mold clamping crosshead position. Specifically, it does the following: The control device 4 stores the minimum lower mold thickness from the preparation work described earlier. This minimum lower mold thickness is set as the reference lower mold thickness. The lower mold thickness measured in step S21 is compared with the reference lower mold thickness. If they match, the mold clamping crosshead position is set to the standard mold clamping crosshead position set in the vertical injection molding machine 1 and is not changed. On the other hand, if the measured lower mold thickness is different from the reference lower mold thickness, the crosshead position shifted by the difference from the standard mold clamping crosshead position is determined as the mold clamping crosshead position.

[0033] The control device 4 executes the mold clamping process in step S23. That is, it drives the crosshead 20 (see Figure 1) to the determined mold clamping crosshead position. This obtains the desired mold clamping force. The injection and holding pressure process is executed in step S24. That is, the screw 32 is driven in the injection device 3 (see Figure 1) to inject the injection material and hold it. Once the injection material injected into the upper mold 17 and lower mold 18 has solidified, the control device 4 executes step S25. That is, the mold clamping device 2 opens the mold. When opening the mold, the distance between the upper movable platen 10 and the rotary table 15 is set to a specified distance. Next, step S26 is executed to rotate the rotary table 15. This changes the lower mold 18 that is to be clamped. The lower mold 18, on which the molded product has been formed, moves to the operating side, that is, the front side of the paper in Figure 1. The molded product is ejected and removed.

[0034] The control device 4 executes step S27. In other words, if the molding cycle is to be continued (YES), it returns to step S21. In step S21, the lower mold thickness is measured for the lower mold 18 that has become the target of clamping. The process is then carried out similarly thereafter. On the other hand, if the operator has requested to stop the molding cycle in step S27 (NO), the process is terminated.

[0035] <First Embodiment: Modified Method of Clamping> The clamping method according to the first embodiment can be modified in various ways. Figure 6 shows a modified clamping method. The modified clamping method is also carried out by the vertical injection molding machine 1 according to the first embodiment shown in Figure 1, so a description of the vertical injection molding machine 1 is omitted. As shown in Figure 6, steps S21, S22, and S23 in the modified clamping method of the first embodiment are the same processes as in the clamping method according to the first embodiment shown in Figure 5. Therefore, a description of these processes is omitted.

[0036] In the modified clamping method, step S29 is executed after step S23. In step S29, the control device 4 calculates the clamping force based on the strain detected by the strain sensor 39 (see Figure 1). It determines whether the clamping force is of the desired magnitude, and if it is (YES), it proceeds to step S24. Steps S24, ..., S27 are the same as the clamping method according to the first embodiment described in Figure 5, so their explanation is omitted. In step S29, if it is determined that the clamping force is not of the desired magnitude (NO), the process is terminated as an abnormality has occurred. One possible cause of not being able to obtain the desired clamping force is, for example, a temperature change in the molds 17 and 18. If the upper mold thickness and lower mold thickness change due to temperature changes, the desired clamping force cannot be obtained. As a countermeasure, for example, the control device 4 is operated at the request of the operator to perform the preparation work according to the first embodiment already described.

[0037] <First Embodiment: Modification of Preparation Work> The preparation work according to the first embodiment can also be modified. In the preparation work according to the first embodiment, the mold thickness was adjusted to match the minimum lower mold thickness among the multiple lower molds 18, 18. However, in the preparation work according to the modified version of the first embodiment, the average lower mold thickness of the multiple lower molds 18, 18 is determined, and the mold thickness is adjusted to match the average lower mold thickness. This will be explained with reference to Figure 7.

[0038] The control device 4 (see Figure 1) executes step S31 shown in Figure 7 to set the mold plate distance between the upper movable platen 10 and the rotary table 15 to a specified distance. Next, it executes step S32, measuring and storing the lower mold thickness of the lower mold 18 to be clamped using the distance sensor 37. The control device 4 executes step S33 to determine whether the measurement and storage of the lower mold thickness has been completed for all lower molds 18, 18. If it is not completed (NO), it executes step S34 to rotate the rotary table 15 and change the lower mold 18 to be clamped. Then it returns to step S32. On the other hand, if it is determined that it has been completed for all lower molds 18, 18 (YES), it proceeds to step S35. The control device 4 calculates the average of the lower mold thicknesses for the multiple lower molds 18, 18.

[0039] Next, the control device 4 (see Figure 1) executes step S36 to calculate the mold thickness. Specifically, it does the following: The control device 4 has the thickness of the upper mold 17, i.e., the upper mold thickness, pre-entered. This upper mold thickness and the average lower mold thickness are added together to calculate the thickness of the upper mold 17 and the lower mold 18, i.e., the mold thickness. Once the mold thickness is calculated, step S37 is executed to adjust the mold thickness. The mold thickness adjustment in step S37 is different from the mold thickness adjustment explained in Figure 4. The control device 4 is equipped with a function that, when given the mold thickness, determines the number of rotations of the tie bar nuts 25, ... based on the given mold thickness and rotates the tie bar nuts 25, .... In other words, the mold thickness adjustment can be performed while the mold clamping device 2 is kept in the open state. The mold thickness adjustment is performed in this manner in step S37. The preparation process is completed.

[0040] When the preparation process according to the modification of the first embodiment is performed, the mold clamping device 2 will have performed mold thickness adjustment based on the average lower mold thickness. In this case, the process of step S22 in the mold clamping method according to the first embodiment, as explained with reference to Figure 5, is slightly modified. Specifically, in step S22, the lower mold thickness of the lower mold 18 to be clamped is compared with the minimum lower mold thickness stored in the control device 4. In other words, the reference lower mold thickness to be compared was the minimum lower mold thickness. However, when the preparation process according to the modification of the first embodiment is performed, the reference lower mold thickness becomes the average lower mold thickness. The control device 4 is pre-stored with the average lower mold thickness as the reference lower mold thickness. Then, in step S22 of the mold clamping method, the lower mold thickness of the lower mold 18 to be clamped should be compared with this reference lower mold thickness.

[0041] [Second Embodiment] Next, the second embodiment will be described. In the first embodiment, during the preparation work, the mold thickness of the lower mold 18, 18, ... with the smallest lower mold thickness was adjusted, and the smallest lower mold thickness was stored. Then, in the clamping method, the lower mold thickness of the lower mold 18 to be clamped was measured, the difference from the stored smallest lower mold thickness was calculated, and the clamping crosshead position was determined based on this difference, and the mold was clamped. In contrast, in the second embodiment, during the preparation work, the lower mold thickness of each of the multiple lower molds 18, 18, ... was measured, and the clamping crosshead position that generates an appropriate clamping force was found and stored as a pair. Then, at the time of clamping, the lower mold thickness of the lower mold 18 to be clamped was measured, and the mold was clamped based on the corresponding stored clamping crosshead position. A detailed explanation follows below.

[0042] The configuration of the vertical injection molding machine according to the second embodiment is the same as that of the vertical injection molding machine 1 according to the first embodiment (see Figure 1). Therefore, the description of the vertical injection molding machine according to the second embodiment will be omitted, and it will be described below as vertical injection molding machine 1. The preparation work and mold clamping method according to the second embodiment, which are performed in the vertical injection molding machine 1 according to the second embodiment, will be described in detail.

[0043] <Preparation work> The preparation work according to the second embodiment will be explained with reference to Figure 8. The control device 4 (see Figure 1) executes step S41 to set the distance between the upper movable platen 10 and the rotary table 15 to a specified distance. Next, it executes step S42 to measure and store the lower mold thickness of the lower mold 18 that is currently to be clamped. Next, it executes step S43. In step S43, the actual clamping is performed. The crosshead 20 is slowly driven while detecting the clamping force with the strain sensor 39. In step S44, once the desired clamping force is obtained, the driving of the crosshead 20 is stopped, and the crosshead position at this time is determined to be the clamping crosshead position for the lower mold 18. The control device 4 stores this clamping crosshead position in association with the lower mold thickness stored in step S42.

[0044] In step S45, the control device 4 determines whether the process described above has been completed for all lower molds 18, 18. If it is not completed (NO), it proceeds to step S46. That is, the rotary table 15 is rotated to change the lower mold 18 to be clamped. Then it returns to step S42. On the other hand, if it is determined that it is completed (YES), the preparation work is completed. After performing the preparation work according to this second embodiment, the control device 4 stores the lower mold thickness and the clamping crosshead position as a pair for all lower molds 18, 18.

[0045] <Mold clamping method> The mold clamping method according to the second embodiment will be explained with reference to Figure 9. The control device 4 executes step S51 to measure the lower mold thickness of the lower mold 18 to be clamped. Next, it executes step S52 to search for a lower mold thickness that matches the measured lower mold thickness from among the lower mold thicknesses of all stored lower molds 18, 18. Then it reads the mold clamping crosshead position stored in relation to the matched lower mold thickness. It executes step S53 to drive the crosshead 20 (see Figure 1) to the read mold clamping crosshead position. That is, it executes the mold clamping process. Step S54 executes the injection holding pressure process, and step S55 executes the mold opening process. Step S56 rotates the rotary table 15 and removes the molded product. In step S57, it is determined whether to continue the molding cycle or not. If it is to continue (YES), it returns to step S51. On the other hand, if it is to end the molding cycle (NO), the process ends.

[0046] <Other variations> The first and second embodiments can be further modified in various ways. For example, although these embodiments have been described as having two lower molds 18, 18, there may be three or more lower molds 18, 18. Also, although the strain sensor 39 has been described as being provided on one tie bar 12, it may be provided on all of the tie bars 12, 12, ... Furthermore, although the distance sensor 37 has been described as being provided on the upper movable platen 10, it may be provided on the upper mold 17 instead.

[0047] The present invention has been described in detail above based on embodiments, but it goes without saying that the present invention is not limited to the embodiments already described, and various modifications are possible without departing from the spirit of the invention. The multiple examples described above can also be implemented in combination as appropriate. [Explanation of Symbols]

[0048] 1 Vertical injection molding machine 2 Mold clamping device 3. Injection device 4. Control device 7 beds 9 fixed plate 10 Upper movable plate 11 Lower movable plate 12 Tie bar 14 Toggle mechanism 15 Rotary table 17 Upper mold 18 Lower mold 20 Crosshead 21 Drive mechanism 24 Thickness adjustment mechanism 25 Tie bar nut 26 Through hole 28 tie bar nut storage hole 29 sprocket 31 Heating cylinder 32 Screw 33 Screw drive mechanism 35 Lifting device 37 Distance sensor 39 Distortion sensor

Claims

1. Fixed plate and An upper movable plate is provided above the aforementioned fixed plate, A lower movable plate is provided below the fixed plate, Multiple tie bars connecting the upper movable plate and the lower movable plate, A toggle mechanism is provided between the fixed platen and the lower movable platen, A rotary table is rotatably mounted on the upper surface of the aforementioned fixed platen, A control device is provided, A mold clamping method is provided for performing mold clamping in a mold clamping device, wherein the upper movable platen is provided with one upper mold, and the rotary table is provided with a plurality of lower molds, and depending on the rotational position of the rotary table, one of the plurality of lower molds aligns with the upper mold to become the target for mold clamping, and when the crosshead of the toggle mechanism is driven to the mold clamping crosshead position, the upper mold and the target lower mold are clamped together and a clamping force is generated, A distance sensor is provided on the upper movable platen or the upper mold, and as a preliminary step, the mold thickness is adjusted based on the minimum lower mold thickness among the lower mold thicknesses of each of the multiple lower molds. The mold clamping method includes a first step of rotating the rotary table to switch the lower mold to be clamped, A second step involves setting the mold plate distance, which is the distance between the upper movable platen and the rotary table, to a predetermined distance, and detecting the lower mold thickness, which is the mold thickness of the lower mold to be clamped, using the distance sensor. A mold clamping method comprising: a third step of determining the position of the mold clamping crosshead according to the detected lower mold thickness and performing mold clamping.

2. Fixed plate and An upper movable plate is provided above the aforementioned fixed plate, A lower movable plate is provided below the fixed plate, Multiple tie bars connecting the upper movable plate and the lower movable plate, A toggle mechanism is provided between the fixed platen and the lower movable platen, A rotary table is rotatably mounted on the upper surface of the aforementioned fixed platen, A control device is provided, A mold clamping method is provided for performing mold clamping in a mold clamping device, wherein the upper movable platen is provided with one upper mold, and the rotary table is provided with a plurality of lower molds, and depending on the rotational position of the rotary table, one of the plurality of lower molds aligns with the upper mold to become the target for mold clamping, and when the crosshead of the toggle mechanism is driven to the mold clamping crosshead position, the upper mold and the target lower mold are clamped together and a clamping force is generated, A distance sensor is provided on the upper movable platen or the upper mold, and as a preliminary work step, the mold thickness is adjusted based on the average lower mold thickness of each of the multiple lower molds. The mold clamping method includes a first step of rotating the rotary table to switch the lower mold to be clamped, A second step involves setting the mold plate distance, which is the distance between the upper movable platen and the rotary table, to a predetermined distance, and detecting the lower mold thickness, which is the mold thickness of the lower mold to be clamped, using the distance sensor. A mold clamping method comprising: a third step of determining the position of the mold clamping crosshead according to the detected lower mold thickness and performing mold clamping.

3. The clamping method according to claim 1 or 2, wherein a strain sensor is provided on the tie bar, and the clamping force is detected by the strain sensor in the third step.

4. Fixed plate and An upper movable plate is provided above the aforementioned fixed plate, A lower movable plate is provided below the fixed plate, Multiple tie bars connecting the upper movable plate and the lower movable plate, A toggle mechanism is provided between the fixed platen and the lower movable platen, A rotary table is rotatably mounted on the upper surface of the aforementioned fixed platen, A control device is provided, A mold clamping method is provided for performing mold clamping in a mold clamping device, wherein the upper movable platen is provided with one upper mold, and the rotary table is provided with a plurality of lower molds, and depending on the rotational position of the rotary table, one of the plurality of lower molds aligns with the upper mold to become the target for mold clamping, and when the crosshead of the toggle mechanism is driven to the mold clamping crosshead position, the upper mold and the target lower mold are clamped together and a clamping force is generated, A distance sensor is provided on the upper movable platen or the upper mold, and a strain sensor is provided on the tie bar. As a preliminary work step, the lower mold thickness is obtained in advance for each of the multiple lower molds, and the position of the crosshead where the clamping force detected by the strain sensor becomes the desired clamping force is defined as the clamping crosshead position. The lower mold thickness and the clamping crosshead position are associated for each of the multiple lower molds and stored in the control device. The mold clamping method includes a first step of rotating the rotary table to switch the lower mold to be clamped, A second step involves setting the mold plate distance, which is the distance between the upper movable platen and the rotary table, to a predetermined distance, and detecting the lower mold thickness, which is the mold thickness of the lower mold to be clamped, using the distance sensor. A mold clamping method comprising: a third step of reading the mold clamping crosshead position stored in relation to the detected lower mold thickness from the control device and clamping the mold based on the mold clamping crosshead position.

5. The clamping method according to claim 4, wherein the clamping force is detected by the strain sensor in the third step.

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