Nozzle touch mechanism, injection molding machine including the same, and nozzle touch method

Abstract

To provide a nozzle touch mechanism for a vertical injection molding machine that can prevent molten resin from leaking out even when the machine enters a holding temperature control phase.SOLUTION: A nozzle touch mechanism 50 includes a pair of ball screw shafts 52, a support frame 54 mounted between the pair of ball screw shafts 52, movable along the ball screw shafts 52, and to which an injection nozzle 46 is attached, a nozzle touch motor 56 for moving the support frame 54, and a control device 15 for controlling the operation of the nozzle touch motor 56. The nozzle touch motor 56 is provided with a fixed nozzle brake function to stop the movement of the support frame 54. Furthermore, the control device 15 turns off the injection nozzle fixing brake function of the nozzle touch motor 56 during the period when the temperature of the injection nozzle 46 is being lowered from a state where the injection nozzle 46 is in nozzle touch with the fixed mold 30, until the temperature of the injection nozzle 46 reaches a predetermined temperature.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a nozzle touch mechanism for bringing an injection nozzle into nozzle touch with a mold, an injection molding machine equipped with the same, and a nozzle touch method. [Background technology]

[0002] In conventional injection molding machines, a nozzle touch mechanism is provided to bring the tip of the injection nozzle into contact with the fixed mold with a desired force (nozzle touch) so that molten resin can be supplied from the injection nozzle to the mold cavity (for example, Patent Document 1).

[0003] The need for such nozzle touch is also present in vertical injection molding machines, where the injection nozzle moves up and down vertically. The nozzle touch mechanism in vertical injection molding machines is equipped with a brake for fixing the injection nozzle to prevent the injection nozzle from applying undesired force (load) to the fixed mold due to its own weight.

[0004] By using this injection nozzle fixing brake, it became possible to maintain the tip of the injection nozzle pressed against the fixed mold with a predetermined force (load). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-91259 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there are problems that need to be solved with the nozzle touch mechanism in vertical injection molding machines.

[0007] To ensure safety, the injection nozzle fixing brake is designed to be applied when no power is supplied, and to be released when power is supplied. For this reason, the supply of power to the injection nozzle fixing brake is usually stopped when the nozzle is touched, thereby braking the movement of the injection nozzle.

[0008] When the injection molding machine is stopped from operating in this nozzle-touched state by reducing the heating of the injection nozzle by the heater and lowering the temperature of the injection nozzle (heat retention control), the injection nozzle may thermally shrink, creating a gap between the injection nozzle and the fixed mold, which could result in leakage of molten resin.

[0009] The present invention has been made in consideration of such problems, and its purpose is to provide a nozzle touch mechanism that can prevent molten resin from leaking even when heat retention control is activated, an injection molding machine equipped with the same, and a nozzle touch method. [Means for solving the problem]

[0010] According to one aspect of the present invention, A nozzle touch mechanism provided in a vertical injection molding machine, A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, the nozzle touch motor has a brake function for fixing the injection nozzle, which stops the movement of the stand; When the temperature of the injection nozzle is lowered from a state in which the injection nozzle is in nozzle contact with the fixed mold, the control device turns off the injection nozzle fixing brake function until the temperature of the injection nozzle is lowered to a predetermined temperature. A nozzle touch mechanism is provided.

[0011] According to another aspect of the present invention, A nozzle touch mechanism provided in a vertical injection molding machine, A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, the nozzle touch motor has a brake function for fixing the injection nozzle, which stops the movement of the stand; When the injection nozzle touches the fixed mold and the temperature of the injection nozzle is increased, the control device turns off the brake function for fixing the injection nozzle until the temperature of the injection nozzle reaches a predetermined temperature, and then presses the stand and the injection nozzle toward the fixed mold by the nozzle touch motor for a preset time, and turns on the brake function for fixing the injection nozzle when the preset time has elapsed. A nozzle touch mechanism is provided.

[0012] Preferably, Before turning off the brake function for fixing the injection nozzle, the control device retracts a screw in a heating cylinder at the tip of which the injection nozzle is provided, thereby reducing the pressure in the heating cylinder.

[0013] According to another aspect of the present invention, There is provided an injection molding machine equipped with the above-described nozzle touch mechanism.

[0014] According to another aspect of the present invention, A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, a nozzle touch method using a nozzle touch mechanism, wherein the nozzle touch motor has a brake function for fixing the injection nozzle that stops the movement of the stand, When the temperature of the injection nozzle is lowered from a state in which the injection nozzle is in nozzle touch with the fixed mold, the injection nozzle fixing brake function of the nozzle touch motor is turned off until the temperature of the injection nozzle is lowered to a predetermined temperature. A nozzle touch method is provided.

[0015] According to another aspect of the present invention, A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, a nozzle touch method using a nozzle touch mechanism, wherein the nozzle touch motor has a brake function for fixing the injection nozzle that stops the movement of the stand, when increasing the temperature of the injection nozzle after the injection nozzle has come into contact with the fixed mold, turning off the brake function for fixing the injection nozzle until the temperature of the injection nozzle reaches a predetermined temperature; The nozzle touch motor presses the base and the injection nozzle toward the fixed mold for a preset time, When a preset time has elapsed, the brake function for fixing the injection nozzle is turned on. A nozzle touch method is provided. [Effects of the Invention]

[0016] According to the nozzle touch mechanism of the present invention, when the injection nozzle is in nozzle touch with the fixed mold and the temperature of the injection nozzle is lowered, the control device turns off the injection nozzle fixing brake function of the nozzle touch motor until the temperature of the injection nozzle drops to a predetermined temperature.

[0017] As a result, even if the injection nozzle thermally shrinks before its temperature drops to a predetermined temperature, the brake function for fixing the injection nozzle is turned off, so the stand and injection nozzle move vertically downward (towards the fixed mold) under their own weight. As a result, no gap is created between the injection nozzle and the fixed mold, preventing leakage of molten resin.

[0018] In addition, the nozzle touch motor presses the stand and injection nozzle toward the fixed mold for a preset period of time, so that the force (nozzle touch force) that presses the lower end of the injection nozzle against the fixed mold during nozzle touch can be generated more reliably. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing an example of an injection molding machine 10 according to an embodiment. [Figure 2] 10 is a flowchart illustrating a heat retention operation of the injection nozzle 46 according to the embodiment. [Figure 3] 10 is a flowchart illustrating the nozzle touch operation of the injection nozzle 46 according to the first modification. [Figure 4] 10 is a flowchart illustrating the nozzle touch operation of the injection nozzle 46 according to the first modification. DETAILED DESCRIPTION OF THE INVENTION

[0020] (Configuration of injection molding machine 10) The injection molding machine 10 according to this embodiment is a machine that manufactures molded products by repeating a molding cycle including mold closing, mold clamping, injecting and filling molten resin, measuring, mold opening, and removing the molded product, and as shown in FIG. 1, is roughly equipped with a mold clamping device 12, an injection device 14, and a control device 15.

[0021] Furthermore, this injection molding machine 10 is a "vertical" injection molding machine 10 in which the injection device 14 is provided above the mold clamping device 12 and the injection nozzle 46, which will be described later, moves up and down in the vertical direction.

[0022] The mold clamping device 12 includes a machine base 16 , a fixed platen 18 , a movable platen 20 , a pressure receiving platen 22 , tie bars 24 , a toggle mechanism 26 , and a mold clamping force sensor 27 .

[0023] The machine base 16 is a member that serves as a base for the other members that make up the mold clamping device 12.

[0024] A fixed mold 30 that constitutes a mold 28 is attached to the fixed platen 18 .

[0025] The movable platen 20 is a member that moves up and down so as to approach and move away from the fixed platen 18, and has a movable mold 33 attached thereto, which constitutes the mold 28. When the movable mold 33 comes into contact with the fixed mold 30, a cavity is formed into which the molten resin is filled.

[0026] The pressure receiving platen 22 is a member fixed to the opposite side (lower side) of the fixed platen 18 when viewed from the movable platen 20.

[0027] The tie bars 24 are round bar-shaped members having one end fixed to the fixed platen 18 and the other end fixed to the pressure receiving platen 22. The tie bars 24 are inserted into tie bar insertion holes 31 formed in the movable platen 20 arranged between the fixed platen 18 and the pressure receiving platen 22. This allows the movable platen 20 to slide in the up and down direction in the figure on the machine base 16 along the tie bars 24. A plurality of tie bars 24 (for example, four) are used.

[0028] The toggle mechanism 26 is a mechanism for moving the movable platen 20 toward or away from the fixed platen 18 , and the mold clamping drive device 32 is attached to the pressure receiving platen 22 .

[0029] The movable platen 20 moves along the tie bars 24 (moves up and down in the drawing) as the driving force of the mold clamping drive device 32 is transmitted through the toggle mechanism 26. When the movable platen 20 moves downward, the fixed mold 30 and the movable mold 33 move apart. On the other hand, when the movable platen 20 moves upward, the fixed mold 30 and the movable mold 33 come into contact with each other, forming a cavity (internal space) inside the mold 28. Then, when pressure is further applied in a direction that moves the movable platen 20 upward, the fixed mold 30 and the movable mold 33 are clamped.

[0030] The mold clamping force sensor 27 is a sensor that measures the mold clamping force of the movable mold 33 relative to the fixed mold 30, and is attached to at least one tie bar 24. Specifically, the distortion of the tie bar 24 during mold clamping is measured, and the control device 15 calculates the mold clamping force based on the amount of distortion. Note that the position and type of the mold clamping force sensor 27 are not limited to those in this embodiment.

[0031] The injection device 14 is a device that injects and fills molten resin into the cavity (hollow) of the mold 28 formed when the movable mold 33 comes into contact with the fixed mold 30, and has a heating cylinder 44, a heater 45 arranged around the heating cylinder 44, an injection nozzle 46 whose tip abuts against the mold 28, a screw 48 arranged inside the heating cylinder 44 and that sends molten resin to the injection nozzle 46, and a nozzle touch mechanism 50.

[0032] The nozzle touch mechanism 50 has the role of bringing the tip of the injection nozzle 46 into contact with and away from the fixed mold 30 via the fixed platen 18 of the mold clamping device 12, and in this embodiment, it roughly comprises a pair of ball screw shafts 52, a stand 54, and a nozzle touch motor 56.

[0033] The pair of ball screw shafts 52 are axes used to move the stand 54, and are arranged parallel to each other so as to extend vertically up and down, with their lower ends connected to the upper surface of the fixed platen 18 of the mold clamping device 12.

[0034] The base 54 is a member that is installed between the pair of ball screw shafts 52 and is movable up and down along the ball screw shafts 52. The injection nozzle 46 is attached to the base 54 facing downward, and when the base 54 moves downward, the lower end of the injection nozzle 46 comes close to the fixed mold 30.

[0035] The nozzle touch motor 56 has the role of moving the base 54 in the vertical direction. The nozzle touch motor 56 also has an injection nozzle fixing brake function that stops the movement of the base 54. If the power supplied to the nozzle touch motor 56 is cut off for some reason, the injection nozzle fixing brake function will be activated to stop the movement of the base 54. Of course, the nozzle touch motor 56 can also turn off (release) this injection nozzle fixing brake function and move the base 54 (and injection nozzle 46) vertically downward (towards the fixed mold 30) under its own weight.

[0036] (Characteristics of control by the control device 15) The control device 15 is a device that controls all of the molding cycles performed by the injection molding machine 10. In the following, only the controls necessary to explain the invention of the present application will be described.

[0037] When the lower end of the injection nozzle 46 is brought into contact (nozzle touch) with the fixed mold 30, the control device 15 operates the nozzle touch motor 56 to move the stand 54 (and the injection nozzle 46) downward. With the injection nozzle 46 in nozzle touch with the fixed mold 30, the screw 48 is operated to inject molten resin from the lower end of the injection nozzle 46 into the cavity of the mold 28, thereby forming a molded product.

[0038] 2, when the operation of the injection molding machine 10 is halted, the output of the heater 45 is reduced to lower the temperature of the injection nozzle 46 (S101) while the lower end of the injection nozzle 46 is in nozzle touch with the fixed mold 30 (S100). At this time, the control device 15 turns off the injection nozzle fixing brake function of the nozzle touch motor 56 until the temperature of the injection nozzle 46 drops to a predetermined temperature (S102).

[0039] As a result, even if injection nozzle 46 thermally shrinks before its temperature drops to a predetermined temperature, the brake function for fixing the injection nozzle is turned off, so stand 54 and injection nozzle 46 move vertically downward (toward fixed mold 30) under their own weight. As a result, no gap is created between injection nozzle 46 and fixed mold 30, preventing leakage of molten resin.

[0040] Thereafter, when the temperature of the injection nozzle 46 reaches the warming temperature (Yes in S103), the control device 15 turns on the injection nozzle fixing brake function of the nozzle touch motor 56 (S104).

[0041] Although the control when heater warmth control is used has been shown, this is not limiting and even when the heater 45 is turned off, the injection nozzle fixing brake function remains off until the injection nozzle 46 drops to a predetermined temperature. Then, when the temperature of the injection nozzle 46 reaches the predetermined temperature, the control device 15 may turn on the injection nozzle fixing brake function of the nozzle touch motor 56.

[0042] Furthermore, when the heater 45 is turned off, a timer set to an arbitrary time is operated until the injection nozzle 46 drops to a predetermined temperature, and the injection nozzle fixing brake function is turned off, and the injection nozzle fixing brake function may be repeatedly turned on and off until an arbitrarily set number of times is completed.

[0043] (Variation 1) In the above-described embodiment, the operation of the control device 15 when the operation of the injection molding machine 10 is stopped after the lower end of the injection nozzle 46 is brought into nozzle touch has been described. However, instead of or in addition to this, it is also possible to more reliably generate a force (nozzle touch force) that presses the lower end of the injection nozzle 46 against the fixed mold 30 at the time of nozzle touch.

[0044] 3 and 4, after performing the nozzle touch (S200), the control device 15 waits for the user to press a "nozzle touch temperature increase" key (for example, located on an operation panel not shown) (S201). When the user presses the "nozzle touch temperature increase" key (Yes in S201), the control device 15 operates the heater 45 to start increasing the temperature of the injection nozzle 46 (S202). At the same time, the control device 15 turns off the injection nozzle fixing brake function of the nozzle touch motor 56 (S203).

[0045] As the temperature of the injection nozzle 46 is increased by the heater 45, the injection nozzle 46 expands due to heat, but because the brake function for fixing the injection nozzle is turned off, the force due to the thermal expansion is used to extend the base 54 and the injection nozzle 46 itself upward, and no significant fluctuations occur in the nozzle touch force.

[0046] When the injection nozzle 46 reaches a predetermined temperature (Yes in S204), the control device 15 prompts the user to complete the nozzle touch (S205: for example, display a message such as "Please complete the nozzle touch" on an operation panel not shown).

[0047] Then, the control device 15 waits for the user to press a "nozzle touch" key (for example, located on an operation panel not shown) (S206). When the user presses the "nozzle touch" key (Yes in S206), the control device 15 moves the base 54 (and injection nozzle 46) toward the fixed mold 30 for a preset time (for example, 2 seconds) (S207: since the nozzle is touching, the base 54 (and injection nozzle 46) do not actually move, and the lower end of the injection nozzle 46 is pressed against the fixed mold 30 by the pressing force of the nozzle touch motor 56).

[0048] When a preset time has elapsed, the control device 15 turns on the injection nozzle fixing brake function of the nozzle touch motor 56 (S208).

[0049] As a result, the force (nozzle touch force) that presses the lower end of the injection nozzle 46 against the fixed mold 30 during nozzle touch can be generated more reliably.

[0050] (Variation 2) Furthermore, if the residual pressure inside the heating cylinder 44 is high, releasing the brake function for fixing the injection nozzle when the heater is kept warm (OFF) could result in resin leakage due to the residual pressure inside the heating cylinder 44. Therefore, one option is to forcibly retract the screw 48 to release the residual pressure inside the heating cylinder 44, thereby reducing the pressure inside the heating cylinder 44, and then turn off the brake function for fixing the injection nozzle. Specifically, if the internal pressure of the heating cylinder 44 is higher than the pressing force due to the injection device weight of approximately 4.9 KN (500 kgf), the internal pressure of the heating cylinder 44 is set to 130 MPa (resin reaction force 3.7 KN) or less.

[0051] After the internal pressure of the heating cylinder 44 is reduced, the brake function for fixing the injection nozzle is turned off until the temperature of the injection nozzle 46 reaches a predetermined temperature, and when the temperature of the injection nozzle 46 reaches the predetermined temperature, the control device 15 turns on the brake function for fixing the injection nozzle of the nozzle touch motor 56.

[0052] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0053] 10... injection molding machine, 12... mold clamping device, 14... injection device, 15... control device, 16... machine base, 18... fixed platen, 20... movable platen, 22... pressure receiving platen, 24... tie bar, 26... toggle mechanism, 27... mold clamping force sensor, 28... mold, 30... fixed mold, 31... tie bar insertion hole, 32... mold clamping drive device, 33... movable mold, 44... heating cylinder, 45... heater, 46... injection nozzle, 48... screw 50... nozzle touch mechanism, 52... ball screw shaft, 54... stand, 56... nozzle touch motor

Claims

1. A nozzle touch mechanism provided in a vertical injection molding machine, A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, the nozzle touch motor has a brake function for fixing the injection nozzle, which stops the movement of the stand; When the temperature of the injection nozzle is lowered from a state in which the injection nozzle is in nozzle contact with the fixed mold, the control device turns off the injection nozzle fixing brake function until the temperature of the injection nozzle is lowered to a predetermined temperature. Nozzle touch mechanism.

2. A nozzle touch mechanism provided in a vertical injection molding machine, A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, the nozzle touch motor has a brake function for fixing the injection nozzle, which stops the movement of the stand; When the injection nozzle touches the fixed mold and the temperature of the injection nozzle is increased, the control device turns off the brake function for fixing the injection nozzle until the temperature of the injection nozzle reaches a predetermined temperature, and then presses the stand and the injection nozzle toward the fixed mold by the nozzle touch motor for a preset time, and turns on the brake function for fixing the injection nozzle when the preset time has elapsed. Nozzle touch mechanism.

3. Before turning off the brake function for fixing the injection nozzle, the control device retracts a screw in a heating cylinder at the tip of which the injection nozzle is provided, thereby reducing the pressure in the heating cylinder. The nozzle touch mechanism according to claim 1 or 2.

4. An injection molding machine comprising the nozzle touch mechanism according to claim 1 or 2.

5. A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, a nozzle touch method using a nozzle touch mechanism, wherein the nozzle touch motor has a brake function for fixing the injection nozzle that stops the movement of the stand, When the temperature of the injection nozzle is lowered from a state in which the injection nozzle is in nozzle touch with the fixed mold, the injection nozzle fixing brake function of the nozzle touch motor is turned off until the temperature of the injection nozzle is lowered to a predetermined temperature. Nozzle touch method.

6. A pair of ball screw shafts; a base that is installed between the pair of ball screw shafts, is movable along the ball screw shafts, and has an injection nozzle attached thereto; a nozzle touch motor that moves the stand; a control device for controlling the operation of the nozzle touch motor, a nozzle touch method using a nozzle touch mechanism, wherein the nozzle touch motor has a brake function for fixing the injection nozzle that stops the movement of the stand, when increasing the temperature of the injection nozzle after the injection nozzle has come into contact with the fixed mold, turning off the brake function for fixing the injection nozzle until the temperature of the injection nozzle reaches a predetermined temperature; The nozzle touch motor presses the base and the injection nozzle toward the fixed mold for a preset time, When a preset time has elapsed, the brake function for fixing the injection nozzle is turned on. Nozzle touch method.

Images