Mould locking device and method of plastic injection molding machine

Abstract

The invention discloses a mold locking device and method for a plastic injection molding machine. A fixed mold plate is fixedly arranged on a rack, and a movable mold plate is arranged on the rack in a sliding manner; the servo motor is fixed on the movable template; threads are arranged at the right ends of the pull rods; the end, provided with threads, of the pull rod penetrates through the movable mold plate, and the pull rod is rotationally matched with the movable mold plate. The servo motor is in transmission connection with the pull rods to drive the pull rods to rotate synchronously; the stress sleeve is arranged on the fixed mold plate in a penetrating manner and is in fastening fit with the fixed mold plate; the pull rod is inserted into the stress sleeve and is in threaded fit with the stress sleeve; the large nut is arranged at the end, away from the movable mold plate, of the stress sleeve in a sleeving mode and matched with the stress sleeve in a threaded mode, and a thrust column is arranged on the outer wall of the large nut. The number of the thrust hydraulic cylinders is multiple, the thrust hydraulic cylinders are rotationally installed on the fixed mold plate, and piston rods of the thrust hydraulic cylinders are hinged to the thrust column so as to push the large nut to rotate relative to the stress sleeve. The device has the advantages of being simple in structure, stable in operation, high in efficiency and low in cost.

Description

Technical Field

[0001] The invention relates to the technical field of two-platen equipment for plastic injection molding, and in particular to a mold locking device and method for a plastic injection molding machine. Background Art

[0002] The current clamping device of the plastic injection molding machine has a set of molds installed between the fixed platen and the movable platen. Two opening and closing mold cylinders are installed on the fixed platen. The piston rods extending from the cylinders are connected to the movable platen. Four tie rods, i.e., one end of the piston rods with pistons, are installed in the fixed platen and covered with a large booster cylinder. After the hydraulic pressure increases, a clamping force on the mold is formed. One end of the tie rod with a spiral extends toward the relative through hole of the movable platen. The movable platen is provided with an opening and closing nut device for engaging the tie rod spiral relative to the light hole extending from the tie rod, and a relatively long guide frame is provided between the movable platen and the frame. The above-mentioned clamping device can complete the molding of ordinary products, but there are many action cylinders, high action conversion accuracy requirements, long conversion time, and rapid wear of hydraulic seals, which affects the maintenance of hydraulic pressure. The movable platen has no tie rod guide, so the movement accuracy is poor. The tie rod is always in a relatively long cantilever beam state, which affects the force accuracy and use quality. The manufacturing of this clamping device is complex, with high manufacturing cost and high maintenance cost. Summary of the invention

[0003] The purpose of the present invention is to provide a clamping device and method for a plastic injection molding machine to solve the above problems.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A clamping device for a plastic injection molding machine, comprising a frame, a movable platen, a fixed platen, a servo motor, a tie rod, a force sleeve, a large nut and a thrust hydraulic cylinder; the fixed platen is fixedly arranged on the frame, and the movable platen is slidably arranged on the frame; the servo motor is fixed to the movable platen; there are multiple tie rods, and the right end of the tie rod is provided with a thread; one end of the tie rod provided with a thread passes through the movable platen, and the tie rod is rotatably matched with the movable platen; the servo motor is transmission-connected with the tie rods to drive each of the tie rods to rotate synchronously The movable template is movable; the force-bearing sleeve is passed through the fixed template and is tightly matched with the fixed template; the pull rod is inserted into the force-bearing sleeve and is threadedly matched with the force-bearing sleeve; the large nut is sleeved on the end of the force-bearing sleeve away from the movable template, and the large nut is threadedly matched with the force-bearing sleeve, and a thrust column is provided on the outer wall of the large nut; the number of the thrust hydraulic cylinders is multiple, and the thrust hydraulic cylinders are rotatably installed on the fixed template, and the piston rod of the thrust hydraulic cylinder is hinged to the thrust column to push the large nut to rotate relative to the force-bearing sleeve.

[0006] Preferably, a driving synchronous pulley is installed on the output shaft of the servo motor. A main synchronous pulley and a secondary synchronous pulley are installed at the left end of one of the pull rods, and the secondary synchronous pulleys are respectively installed at the left ends of the remaining pull rods. The driving synchronous pulley is connected to the main synchronous pulley through a synchronous belt, and the secondary synchronous pulley is connected to the driven synchronous pulleys of the remaining pull rods through a synchronous belt, so that each pull rod rotates synchronously.

[0007] Preferably, the moving template is provided with a plurality of through holes. A first step is provided at the outer end of the through hole, and a second step is provided at the inner end. An inner pressure ring and a flat copper belt are installed in the first step. An outer pressure ring is provided between the secondary synchronous pulley and the inner pressure ring. A stress nut is further provided at the left end of the pull rod. An inner cone is installed in the second step. An outer cone nut that cooperates with the inner cone is threadedly connected to the pull rod. A conical copper ring is sleeved on the outer wall of the outer cone nut. The pull rod passes through the through hole. The secondary synchronous pulley abuts against the outer pressure ring. The outer cone nut is threadedly connected to the pull rod and presses the conical copper ring against the inner wall of the inner cone.

[0008] Preferably, it further includes a hinge seat and a hinge shaft. A hinge plate is provided at the tail of the cylinder body of the thrust hydraulic cylinder. The hinge seat is fixedly installed on the fixed template. The hinge plate is inserted into the hinge seat, and the hinge shaft passes through the hinge seat and the hinge plate, so that the hinge plate is rotatably installed on the hinge seat.

[0009] Preferably, the moving template is provided with a safety rod that extends towards the fixed template side. The moving template is provided with a safety hole and a shutter corresponding to the safety rod. The shutter is rotatably arranged at one end of the safety hole close to the moving template.

[0010] Preferably, the frame is provided with a limit block and an adjustment block. The limit block is fixedly arranged on the frame and is located on the left side of the moving template. The adjustment block is arranged at the bottom of the moving template, and the adjustment block is movably arranged with the frame. The adjustment block is located on the right side of the moving template.

[0011] Preferably, it further includes a demoulding mechanism. The demoulding mechanism is arranged on the moving template. The demoulding mechanism includes an ejection hydraulic cylinder, a fixing plate, equal-height columns, an ejection plate and ejection rods. The fixing plate is fixed to the moving template through the equal-height columns. An activity space is left between the fixing plate and the moving template. The ejection hydraulic cylinder is fixed to the fixing plate. There are multiple ejection rods, which are respectively fixed to the ejection plate. The ejection plate is arranged in the activity space. The ejection rods pass through the moving template and extend into the mold. The piston rod of the ejection hydraulic cylinder passes through the fixing plate and is fixedly connected to the ejection plate.

[0012] A mold clamping method for a plastic injection molding machine, which is applied to the mold clamping device of a plastic injection molding machine as described above, includes the following steps:

[0013] Step 1: The servo motor drives the tie rod to rotate, causing the moving template to move towards the fixed template, and the fixed mold and the moving mold are initially closed;

[0014] Step 2: The thrust hydraulic cylinder pushes the large nut to rotate, so that the mold clamping force reaches 70% of the preset mold clamping force;

[0015] Step 3: Inject plastic into the mold and gradually increase the injection pressure;

[0016] Step 4: When the injection pressure reaches 70% of the preset injection pressure, the thrust hydraulic cylinder increases synchronously with the injection pressure until the injection pressure reaches the preset injection pressure and the mold clamping force reaches the preset mold clamping force;

[0017] Step 5: Hold the pressure and cool;

[0018] Step 6: The hydraulic thrust cylinder pulls the large nut to rotate to reduce the mold clamping force;

[0019] Step 7: The servo motor drives the tie rod to rotate, causing the moving template to move away from the fixed template, and the fixed mold and the moving mold are opened.

[0020] One embodiment of the present invention has the following beneficial effects:

[0021] 1. The tie rod and the force-bearing sleeve always maintain a threaded connection, avoiding the tie rod from being suspended and causing bending, thus avoiding jitter when the tie rod rotates and making the movement more stable;

[0022] 2. Multiple tie rods can play a guiding role, eliminating the need for additional guide rods, reducing manufacturing costs and the resistance of equipment operation;

[0023] 3. The tie rod and the force-bearing sleeve adopt a threaded fit, and the mold is opened, closed, and clamped through a screw pair, which has the advantages of fast action, fast pressure build-up, and high rigidity. It can effectively save the cycle time of equipment operation, and can simultaneously open the mold and melt the plastic when forming thin-walled products, with higher production efficiency;

[0024] 4. By increasing the mold clamping force as the injection pressure increases, the service life of the force-bearing parts and the mold can be improved, and it is beneficial to exhaust air from the mold cavity during the injection process, resulting in a higher product yield and better quality. Description of the Drawings

[0025] The drawings further illustrate the present invention, but the content in the drawings does not constitute any limitation to the present invention.

[0026] Figure 1 It is the front view structural schematic diagram of one embodiment of the present invention;

[0027] Figure 2 It is a schematic right view structure diagram of one embodiment of the present invention;

[0028] In the attached drawings: 1-frame, 2-moving template, 3-fixed template, 4-servo motor, 5-tension rod, 6-force sleeve, 7-large nut, 8-thrust hydraulic cylinder, 9-thrust column, 10-driving synchronous pulley, 11-main synchronous pulley, 12-secondary synchronous pulley, 13-inner pressure ring, 14-flat copper belt, 15-outer pressure ring, 16-force nut, 17-inner cone, 18-outer cone nut, 19-conical copper ring, 20-hinge seat, 21-hinge shaft, 22-hinge plate, 23-safety rod, 24-safety hole, 25-gate plate, 26-limit block, 27-adjusting block, 28-ejecting hydraulic cylinder, 29-fixed plate, 30-equivalent height column, 31-ejecting plate, 32-ejecting rod. Detailed implementation manners

[0029] The following details the implementation manners of the present invention. Examples of the implementation manners are shown in the attached drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The implementation manners described below with reference to the attached drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention. In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the attached drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0030] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection, or a connection capable of mutual communication; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0032] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments.

[0034] A clamping device of a plastic injection molding machine according to this embodiment, as Figure 1 and 2As shown, it includes a frame 1, a movable platen 2, a fixed platen 3, a servo motor 4, a tie rod 5, a force sleeve 6, a large nut 7 and a thrust hydraulic cylinder 8; the fixed platen 3 is fixedly arranged on the frame 1, and the movable platen 2 is slidably arranged on the frame 1; the servo motor 4 is fixed to the movable platen 2; there are multiple tie rods 5, and the right end of the tie rod 5 is provided with a thread; one end of the tie rod 5 provided with a thread passes through the movable platen 2, and the tie rod 5 is rotatably matched with the movable platen 2; the servo motor 4 is transmission-connected with the tie rod 5 to drive each of the tie rods 5 to rotate synchronously; the The force-bearing sleeve 6 is passed through the fixed template 3 and is tightly matched with the fixed template 3; the pull rod 5 is inserted into the force-bearing sleeve 6 and is threadedly matched with the force-bearing sleeve 6; the large nut 7 is sleeved on the end of the force-bearing sleeve 6 away from the movable template 2, and the large nut 7 is threadedly matched with the force-bearing sleeve 6, and a thrust column 9 is provided on the outer wall of the large nut 7; the number of the thrust hydraulic cylinders 8 is multiple, and the thrust hydraulic cylinders 8 are rotatably installed on the fixed template 3, and the piston rod of the thrust hydraulic cylinder 8 is hinged to the thrust column 9 to push the large nut 7 to rotate relative to the force-bearing sleeve 6.

[0035] In actual use, the moving mold is installed on the mold surface of the moving template 2, and the fixed mold is installed on the mold surface of the fixed template 3. A servo motor 4 is installed at the lower end of the back of the moving template 2. The output shaft of the servo motor 4 is drivingly connected to the pull rod 5. When the servo motor 4 is started, it drives multiple pull rods 5 to rotate. The rotation speeds of the multiple pull rods 5 are the same, realizing the light-load and high-speed mold opening and closing actions of the device. The extended section of the pull rod 5 to the right is provided with threads that meet the maximum mold thickness and the maximum mold opening stroke and is connected to the force-bearing sleeve 6. The force-bearing sleeve 6 has internal threads. The left end of the force-bearing sleeve 6 is in threaded cooperation with the pull rod 5. One end of the outer wall of the force-bearing sleeve 6 with threads is inserted into the fixed template 3 from right to left, and the threaded section extending to the right is inserted into the pressure ring and screwed into the large nut 7 and tightened to the end. When the pull rod 5 rotates, since the threads of the pull rod 5 are in cooperation with the threads of the force-bearing sleeve 6, the moving template 2 is driven to approach or move away from the fixed template 3, thereby realizing the mold opening and closing actions. The speed of mold opening and closing is equal to the rotation speed of the pull rod 5 multiplied by the pitch of the threads of the extended section of the pull rod 5. A thrust column 9 and a thrust hydraulic cylinder 8 are provided outside the large nut 7. When the piston rod of the thrust hydraulic cylinder 8 extends, it drives the thrust column 9 to rotate the large nut 7. The rotation of the large nut 7 drives the force-bearing sleeve 6 to move to the right and simultaneously generates a pulling force that drives the pull rod 5 to move to the right, forming a clamping force. Similarly, when the thrust hydraulic cylinder 8 contracts, a large mold opening force is generated. Since the force-bearing sleeve 6 is fixedly connected to the fixed template 3, that is, the force-bearing sleeve 6 cannot rotate relative to the fixed template 3, the specific connection structure between the force-bearing sleeve 6 and the fixed template 3 is as follows. A plane is provided on the outer wall of the force-bearing sleeve 6, and a groove corresponding to the plane on the outer wall of the force-bearing sleeve 6 is provided on the left side of the fixed template 3, that is, the mold surface. After the force-bearing sleeve 6 is inserted into the fixed template 3, an anti-rotation plate is inserted between the plane on the outer wall of the force-bearing sleeve 6 and the groove of the fixed template 3 to press the force-bearing sleeve 6 tightly in the fixed template 3, thereby realizing the fixed connection between the force-bearing sleeve 6 and the fixed template 3. Therefore, when the pull rod 5 or the large nut 7 rotates, the fixed template 3 will not rotate, and when the large nut 7 rotates, the force-bearing sleeve 6 can move slightly, so that when the large nut 7 rotates, it can apply force to the pull rod 5 through the slight movement of the force-bearing sleeve 6 to provide a large clamping force and mold opening force.

[0036] During the production process, first start the servo motor 4 to drive each pull rod 5 to rotate. At this time, the moving template 2 moves rapidly towards the fixed template 3. When the moving mold and the fixed mold are in close contact during the mold closing process, the servo motor 4 stops rotating and at the same time the thrust hydraulic cylinder 8 injects pressure oil to push the piston rod out to drive the large nut 7 to rotate, and at the same time pull the force-bearing sleeve 6 to move to the right to generate a set clamping force. When the molded product is cooled and solidified, prepare for high-pressure mold opening. The thrust hydraulic cylinder 8 injects pressure oil in the reverse direction. After the large nut 7 rotates in the reverse direction and the clamping force is eliminated, the servo motor 4 rotates for low-pressure mold opening. The magnitude of the pressure of the pressure oil injected into the forward thrust hydraulic cylinder 8 determines the magnitude of the clamping force generated.

[0037] Further, a driving synchronous pulley 10 is installed on the output shaft of the servo motor 4. A main synchronous pulley 11 and a secondary synchronous pulley 12 are installed at the left end of one of the pull rods 5, and the secondary synchronous pulleys 12 are respectively installed at the left ends of the remaining pull rods 5. The driving synchronous pulley 10 is in transmission connection with the main synchronous pulley 11 through a synchronous belt, and the secondary synchronous pulley 12 is in transmission connection with the driven synchronous pulleys of the remaining pull rods 5 through a synchronous belt, so that the pull rods 5 rotate synchronously.

[0038] By setting the tooth number ratio of the main synchronous pulley 11 and the main synchronous pulley 11, the rotational speed of the driving synchronous pulley 10 is fast. After being transmitted by the synchronous belt, the rotational speed of the main synchronous pulley 11 becomes slow. By decelerating, the torque of the rotation of the pull rod 5 is increased, so that the moving template 2 can be more easily driven to slide on the frame 1.

[0039] Further, the moving template 2 is provided with a plurality of through holes. A first step is provided at the outer end of the through hole, and a second step is provided at the inner end. An inner pressure ring 13 and a flat copper belt 14 are installed in the first step. An outer pressure ring 15 is provided between the secondary synchronous pulley 12 and the inner pressure ring 13. A force-bearing nut 16 is further provided at the left end of the pull rod 5. An inner cone 17 is installed in the second step. The pull rod 5 is threadedly connected with an outer cone nut 18 that cooperates with the inner cone 17. A conical copper ring 19 is sleeved on the outer wall of the outer cone nut 18. The pull rod 5 passes through the through hole. The secondary synchronous pulley 12 abuts against the outer pressure ring 15. The outer cone nut 18 is threadedly connected with the pull rod 5 and presses the conical copper ring 19 against the inner wall of the inner cone 17.

[0040] The conical copper ring 19 and the flat copper belt 14 have the functions of high-pressure resistance and wear resistance under high-speed rotation. Under the high-speed rotation of the pull rod 5, the wear can be effectively reduced, and the high pressure brought by mold clamping can be borne. The inner pressure ring 13, the flat copper belt 14, the outer pressure ring 15, the inner cone 17, the outer cone nut 18 and the conical copper ring 19 are installed on both sides of the through hole, which can play a limiting role on the pull rod 5, so that the pull rod 5 can only rotate relative to the fixed template 3 and cannot move, so that the pull rod 5 can pull the moving template 2 to move along the frame 1 when rotating, so as to realize the mold opening and closing actions.

[0041] Further, it further includes a hinge seat 20 and a hinge shaft 21. A hinge plate 22 is provided at the tail of the cylinder body of the thrust hydraulic cylinder 8. The hinge seat 20 is fixedly installed on the fixed template 3. The hinge plate 22 is inserted into the hinge seat 20, and the hinge shaft 21 passes through the hinge seat 20 and the hinge plate 22, so that the hinge plate 22 is rotatably installed on the hinge seat 20.

[0042] The hinge plate 22 is hinged to the hinge seat 20 through the hinge shaft 21, so that the thrust hydraulic cylinder 8 can rotate relative to the hinge seat 20. During the process of the thrust hydraulic cylinder 8 pushing the large nut 7 to rotate, it can rotate a certain angle accordingly, avoiding jamming.

[0043] Further, the moving template 2 is provided with a safety rod 23, and the safety rod 23 extends towards the fixed template 3; the moving template 2 is provided with a safety hole 24 and a gate plate 25 corresponding to the safety rod 23, and the gate plate 25 is rotatably arranged at one end of the safety hole 24 close to the moving template 2.

[0044] Setting the gate plate 25 at the safety hole 24 can play a role in protecting the safety of operators. When there are operators between the moving template 2 and the fixed template 3, rotate the gate plate 25 downward to block the safety hole 24. At this time, the safety rod 23 cannot penetrate into the safety hole 24, that is, the moving template 2 cannot be closed, so that there is always a space between the moving template 2 and the fixed template 3, avoiding safety accidents; when the operator leaves between the moving template 2 and the fixed template 3, swing the gate plate 25 upward, the safety rod 23 can pass through the safety hole 24, and the closing action of the fixed template 3 and the moving template 2 proceeds normally.

[0045] Further, the frame 1 is provided with a limit block 26 and an adjusting block 27. The limit block 26 is fixedly arranged on the frame 1 and is located on the left side of the moving template 2. The adjusting block 26 is arranged at the bottom of the moving template 2, and the adjusting block 26 is movably arranged with the frame 1, and the adjusting block 26 is located on the right side of the moving template 2.

[0046] A limit block 26 is provided at the left end of the frame 1 to prevent the main and auxiliary pull rods 5 from coming out when the device is at the maximum opening distance; the adjusting block 27 is installed on the frame 1, and the top surface of the adjusting block 27 is an inclined surface. By changing the distance that the adjusting block 27 is inserted into the moving template 2, the coaxiality and perpendicularity of the central axes of the moving template 2 and the fixed template 3 can be adjusted.

[0047] Further, it further includes a demoulding mechanism. The demoulding mechanism is arranged on the moving template 2. The demoulding mechanism includes a jacking hydraulic cylinder 28, a fixing plate 29, equal-height columns 30, a jacking plate 31 and jacking rods 32. The fixing plate 29 is fixed to the moving template 2 through the equal-height columns 30, and there is an activity space between the fixing plate 29 and the moving template 2; the jacking hydraulic cylinder 28 is fixed to the fixing plate 29, and the jacking rods 32 are multiple and are respectively fixed to the jacking plate 31; the jacking plate 31 is arranged in the activity space, the jacking rods 32 pass through the moving template 2 and extend into the mold, and the piston rod of the jacking hydraulic cylinder 28 passes through the fixing plate 29 and is fixedly connected to the jacking plate 31.

[0048] The ejection oil cylinder is installed at the center on the left side of the moving template 2. When the piston rod extends, the piston rod drives the ejection plate 31 to move to the right side. At this time, the ejection rod 32 extends from the mold surface of the mold, so as to eject the injection-molded product, and the product demolding is completed. The ejection force is determined according to the required ejection of the product, and the ejection stroke is determined according to the depth of the ejected product.

[0049] A mold clamping method for a plastic injection molding machine includes the following steps:

[0050] Step 1: The servo motor 4 drives the tie rod 5 to rotate, so that the moving template 2 moves towards the fixed template 3, and the fixed mold and the moving mold are initially clamped.

[0051] Step 2: The thrust hydraulic cylinder 8 pushes the large nut 7 to rotate, so that the mold clamping force reaches 70% of the preset mold clamping force.

[0052] Step 3: Inject plastic into the mold and gradually increase the injection pressure.

[0053] Step 4: When the injection pressure reaches 70% of the preset injection pressure, the thrust hydraulic cylinder 8 increases synchronously with the injection pressure until the injection pressure reaches the preset injection pressure and the mold clamping force reaches the preset mold clamping force.

[0054] Step 5: Hold pressure and cool.

[0055] Step 6: The hydraulic thrust cylinder pulls the large nut 7 to rotate to reduce the mold clamping force.

[0056] Step 7: The servo motor 4 drives the tie rod 5 to rotate, so that the moving template 2 moves away from the fixed template 3, and the fixed mold and the moving mold are opened.

[0057] Adopting the method that the mold clamping force increases simultaneously with the injection pressure. When the pressure of the thrust hydraulic cylinder 8 reaches 70%, the injection action starts. When the injection pressure is greater than 70%, the pressure of the thrust hydraulic cylinder 8 increases together with the injection pressure until the preset mold clamping force is reached. In this process, at the initial injection molding, the mold is filled with air. At this time, the mold clamping force has not reached the maximum, which is beneficial to discharging the air. And subsequently, as the injection pressure increases, the mold clamping force also increases until the preset mold clamping force and injection pressure are reached. This can make the injection-molded product not easily generate cavitation defects, and the injection-molded product is more compact; the service life of the mold and other stressed parts is long, which is convenient for filling the mold, exhausting air and compacting the product.

[0058] The advantages of the above-mentioned mold clamping device compared with the existing mold clamping device are as follows:

[0059] 1. The device extends the pull rod 5 to the right, screws the spiral section into the internal thread of the force-bearing sleeve 6, and except for the mutually mating section, it will not become disengaged after subtracting the minimum die thickness from the maximum die thickness and then adding the maximum mold opening stroke, always maintaining the mating and guiding state, so that the pull rod 5 will not be in a cantilever beam situation, and will not vibrate or bend, and the moving platen 2 moves smoothly.

[0060] 2. There is no need to provide a large guiding frame between the moving platen 2 and the frame 1 of the device, reducing the manufacturing cost and the movement resistance.

[0061] 3. On the left side of the moving platen 2 of the device, there is no need to set up an opening and closing device for the force-bearing nut 16 of the spiral thread of the extended section of the pull rod 5 of the existing two-platen clamping device, avoiding uneven force on the spiral thread of the pull rod 5 when the clamping nut clamps the pull rod 5 and breaking the pull rod 5. At the same time, a set of fine-tuning devices is reduced, reducing the manufacturing cost and the control complexity of the operation.

[0062] 4. The device is provided with a large nut 7 on the right side of the fixed platen 3. The thrust hydraulic cylinder 8 pushes the thrust column 9. According to the lever principle, the torque can be amplified, thereby rotating the large nut 7 to move the force-bearing sleeve 6 to the right, pulling the pull rod 5 to generate a large pulling force, driving the moving platen 2 to generate the clamping force required to clamp the two molds. Compared with the existing two-platen clamping device, four large clamping boost cylinders and four reset cylinders are omitted, reducing a large amount of manufacturing cost and control complexity, and improving the clamping stiffness and stability.

[0063] 5. The clamping force of the device can change together with the size of the injection pressure, making the force-bearing parts and the molds of the device have a long service life, which is beneficial to the formation, exhaust, filling and enrichment of the products.

[0064] 6. Due to the transmission characteristics and force-increasing characteristics of the screw pair, the device has a fast pressure build-up, high rigidity and few actions during the processes of mold closing, mold opening, high-pressure clamping and high-pressure mold opening, can save the machine cycle time, and can perform mold opening and plasticizing simultaneously during molding.

[0065] 7. The device can reduce a large amount of installation time and debugging time, reduce a large number of hydraulic and electrical components, and reduce a large amount of maintenance cost.

[0066] In the description of this specification, the description with reference to terms such as "one embodiment", "certain embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0067] The technical principles of the present invention have been described in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present invention and cannot be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art can readily conceive of other specific embodiments of the present invention without creative efforts, and these equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A clamping device for a plastic injection molding machine, characterized in that: It includes a frame, a movable template, a fixed template, a servo motor, a pull rod, a force sleeve, a large nut and a thrust hydraulic cylinder; the fixed template is fixedly arranged on the frame, and the movable template is slidably arranged on the frame; the servo motor is fixed to the movable template; there are multiple pull rods, and the right end of the pull rod is provided with a thread; the end of the pull rod provided with a thread passes through the movable template, and the pull rod is rotatably matched with the movable template; the servo motor is transmission-connected with the pull rod to drive each of the pull rods to rotate synchronously; the force sleeve is passed through the fixed template and is tightly matched with the fixed template; the pull rod is inserted into the force sleeve and is threadedly matched with the force sleeve; the large nut is sleeved on one end of the force sleeve away from the movable template, and the large nut is threadedly matched with the force sleeve, and a thrust column is provided on the outer wall of the large nut; the number of the thrust hydraulic cylinder is multiple, and the thrust hydraulic cylinder is rotatably installed on the fixed template, and the piston rod of the thrust hydraulic cylinder is hinged to the thrust column to push the large nut to rotate relative to the force sleeve.

2. The clamping device of a plastic injection molding machine according to claim 1, characterized in that: The output shaft of the servo motor is equipped with a driving synchronous pulley, and the left end of one of the pull rods is equipped with a main synchronous pulley and a secondary synchronous pulley, and the left ends of the remaining pull rods are respectively equipped with the secondary synchronous pulleys. The driving synchronous pulley is connected to the main synchronous pulley through a synchronous belt transmission, and the secondary synchronous pulley is connected to the driven synchronous pulleys of the remaining pull rods through a synchronous belt transmission, so that each of the pull rods rotates synchronously.

3. The clamping device of a plastic injection molding machine according to claim 2, characterized in that: The movable template is provided with a plurality of through holes, the outer end of the through hole is provided with a first step, the inner end is provided with a second step, an inner pressure ring and a flat copper belt are installed in the first step, an outer pressure ring is provided between the secondary synchronous pulley and the inner pressure ring, and a force nut is also provided at the left end of the pull rod; an inner cone is installed on the second step, the pull rod is threadedly connected with an outer cone nut matching the inner cone, and a conical copper ring is sleeved on the outer wall of the outer cone nut; the pull rod is inserted into the through hole, the secondary synchronous pulley is abutted against the outer pressure ring, the outer cone nut is threadedly connected to the pull rod, and the conical copper ring is pressed against the inner wall of the inner cone.

4. The clamping device of a plastic injection molding machine according to claim 3, characterized in that: It also includes a hinge seat and a hinge shaft. A hinge plate is provided at the rear of the cylinder body of the thrust hydraulic cylinder. The hinge seat is fixedly installed on the fixed template, the hinge plate is inserted into the hinge seat, and the hinge shaft passes through the hinge seat and the hinge plate so that the hinge plate can be rotatably installed on the hinge seat.

5. The clamping device of a plastic injection molding machine according to claim 4, characterized in that: The movable template is provided with a safety rod, and the safety rod extends to one side of the fixed template; the movable template is provided with a safety hole and a gate plate corresponding to the safety rod, and the gate plate is rotatably arranged at one end of the safety hole close to the movable template.

6. The clamping device of a plastic injection molding machine according to claim 5, characterized in that: The frame is provided with a limit block and an adjustment block, the limit block is fixedly arranged on the frame and located on the left side of the movable template, the adjustment block is arranged at the bottom of the movable template, and the adjustment block is movably arranged with the frame, and the adjustment is located on the right side of the movable template.

7. The clamping device of a plastic injection molding machine according to claim 6, characterized in that: Further included is a demolding mechanism, which is arranged on the moving template. The demolding mechanism includes an ejecting hydraulic cylinder, a fixing plate, equal-height columns, an ejecting plate and ejecting rods. The fixing plate is fixed to the moving template through the equal-height columns, and there is an activity space between the fixing plate and the moving template. The ejecting hydraulic cylinder is fixed to the fixing plate. There are multiple ejecting rods, which are respectively fixed to the ejecting plate. The ejecting plate is arranged in the activity space. The ejecting rods pass through the moving template and extend into the mold. The piston rod of the ejecting hydraulic cylinder passes through the fixing plate and is fixedly connected to the ejecting plate.

8. A mold clamping method for a plastic injection molding machine, characterized in that, Applied to the mold clamping device of a plastic injection molding machine according to any one of claims 1-7, the following steps are included: Step 1: The servo motor drives the tie rods to rotate, causing the moving template to move towards the fixed template, and the fixed mold and the moving mold are initially clamped. Step 2: The thrust hydraulic cylinder pushes the large nut to rotate, so that the clamping force reaches 70% of the preset clamping force. Step 3: Inject plastic into the mold and gradually increase the injection pressure. Step 4: When the injection pressure reaches 70% of the preset injection pressure, the thrust hydraulic cylinder increases synchronously with the injection pressure until the injection pressure reaches the preset injection pressure and the clamping force reaches the preset clamping force. Step 5: Hold the pressure and cool. Step 6: The hydraulic thrust cylinder pulls the large nut to rotate to reduce the clamping force. Step 7: The servo motor drives the tie rods to rotate, causing the moving template to move away from the fixed template, and the fixed mold and the moving mold are opened.

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