A plastic injection anti-eccentric sliding block positioning structure and a molding process

Abstract

The application relates to the technical field of injection molding and mold equipment, in particular to a plastic-coated injection anti-eccentric sliding block positioning structure and a molding process, which comprises a mold body, a lateral sliding block, a sliding block bearing seat, left and right limiting push rods, a screw driving assembly, a position detection assembly and a control processing unit. The abutting state of the push rod and the sliding block end bearing hardening pad is combined, the position detection assembly is used to obtain the push rod position change to form an eccentric state characteristic sequence, and the core is that, according to the eccentric state characteristic sequence, the control processing unit controls the left and right screw driving assemblies to execute a differential retreat, and converts the passive eccentric swing caused by the unbalanced impact of the melt into active support which can be dynamically adjusted. The application overcomes the defects that the sliding block is easy to lose control and deviate in the traditional injection molding, uses active posture adjustment to form a reasonable retreat space, effectively reduces the probability that the product coating layer thickness dispersion, the insert bias and the local flash appear at the same time, and improves the molding quality.

Description

Technical Field

[0001] This invention relates to the field of injection molding and mold equipment technology, specifically to a plastic-coated injection molding anti-eccentric slider positioning structure and molding process. Background Technology

[0002] In the current production process of plastic injection molding, lateral sliders are often used to define the position of inserts and form the cavity boundary. Due to the limitations of mold space and mechanical structure, the slider usually adopts a single force-bearing back side in conjunction with a fixed baffle or a single-point drive linkage for rear-side limiting and motion control. To complete the holding pressure and demolding during the injection molding process, the existing solutions generally adopt an overall synchronous yielding structure, that is, the lateral slider is moved backward by the actuator at a specific process stage to release the yielding space. Although this solution can complete the basic molding action, the lateral impact force formed on both sides of the slider during melt filling is often dynamically unbalanced. The existing single back baffle or rigid synchronous yielding structure cannot detect and offset this force difference, which easily leads to uncontrollable passive swaying of the lateral slider within the existing guide gap. This sluggish response and lack of differentiated adjustment support method results in the final product having a discrete distribution of coating thickness, increased local flash, and damage to the side of the insert by compression, making it difficult to support the consistent manufacturing of high-precision composite components.

[0003] Therefore, improving the controllability of the lateral slider's posture and the dynamic adaptability of its yielding action during the injection molding compression stage has become an urgent problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a plastic-coated injection molding anti-eccentric slider positioning structure and molding process. The objective of the present invention can be achieved through the following technical solutions: A plastic-coated injection molded anti-eccentric slider positioning structure includes: The mold body is provided with a cavity insert, a side slider and a slider support seat. The slider support seat is fixed to the side step surface of the mold body and is provided with a dovetail guide rail. The bottom of the side slider is provided with a dovetail groove that slides with the dovetail guide rail, and the gap between the two on one side is 0.03 to 0.08 mm. The two ends of the lateral slider that are close to and away from the cavity insert are respectively provided with a forming end face and a pressure-bearing back face. The pressure-bearing back face is fixed with a left pressure-bearing hardening pad and a right pressure-bearing hardening pad. The outer side of the slider bearing seat is provided with a left limit push rod and a right limit push rod, which are used to abut against the left pressure hardening pad and the right pressure hardening pad, respectively. The left limit push rod and the right limit push rod are respectively connected to the left lead screw drive assembly and the right lead screw drive assembly; The slider support is equipped with a position detection component and a control processing unit. The position detection component is used to detect the positions of the left limit push rod and the right limit push rod. The control processing unit is used to form an eccentric state characteristic sequence that characterizes the slider's swaying trend based on the order of occurrence, intensity of change and continuous trend of the position changes of the left limit push rod and the right limit push rod, and to control the left lead screw drive component and the right lead screw drive component to perform differential retraction.

[0005] In one possible implementation: the left pressure-bearing hardening pad and the right pressure-bearing hardening pad are located in the left half and right half of the pressure-bearing back side, respectively; the front and rear positions of the left pressure-bearing hardening pad and the right pressure-bearing hardening pad are the same; and the vertical height of the left pressure-bearing hardening pad and the right pressure-bearing hardening pad is the same. Both the left and right pressure-bearing hardening pads are hardened steel blocks, and both are fixedly connected to the side slider by countersunk screws.

[0006] In one possible implementation: a shallow concave positioning surface adapted to the shape of the insert is provided on the molding end face, and the edge of the shallow concave positioning surface is rounded; the angle between the inclined surfaces on both sides of the dovetail guide is 60°, and the cavity insert and the side slider form a cavity for molding the plastic-coated part after the mold is closed, and the dovetail guide is used to restrict the side slider to reciprocate in a direction perpendicular to the side wall of the plastic-coated part.

[0007] In one possible implementation: the left limiting push rod passes through the left guide sleeve, the right limiting push rod passes through the right guide sleeve, and both the left and right guide sleeves are fixedly connected to the outer side of the slider support via flanges; the gap between the inner hole of the left and right guide sleeves and the outer circle of the corresponding limiting push rod is 0.02mm to 0.06mm, and both the inner holes of the left and right guide sleeves are provided with oil reservoir grooves, which are filled with high-temperature resistant grease.

[0008] In one possible implementation: the left lead screw drive assembly includes a left lead screw nut seat, a left lead screw and a left servo motor, the rear end of the left limit push rod is fixedly connected to the left lead screw nut seat, the left lead screw is threadedly engaged with the left lead screw nut seat, and the rear end of the left lead screw is connected to the left servo motor; The right lead screw drive assembly includes a right lead screw nut seat, a right lead screw, and a right servo motor. The rear end of the right limit push rod is fixedly connected to the right lead screw nut seat. The right lead screw is threadedly engaged with the right lead screw nut seat. The rear end of the right lead screw is connected to the right servo motor. The left and right lead screws have the same pitch and are both trapezoidal threaded lead screws.

[0009] In one possible implementation: the position detection component includes a left magnetic ruler slider, a right magnetic ruler slider, a left magnetic ruler reading head, and a right magnetic ruler reading head. The left magnetic ruler slider is fixed to the outer circle of the left limit push rod by a clamping ring, and the right magnetic ruler slider is fixed to the outer circle of the right limit push rod by a clamping ring. Both the left and right magnetic ruler reading heads are fixedly connected to the slider support by a bracket. The left magnetic ruler reading head and the left magnetic ruler slider maintain a parallel gap, and the right magnetic ruler reading head and the right magnetic ruler slider maintain a parallel gap.

[0010] In one possible implementation: a pressure plate is provided above the lateral slider, the pressure plate is fixedly connected to the slider support, and the vertical gap between the lower surface of the pressure plate and the upper surface of the lateral slider is 0.05mm to 0.12mm; the front ends of the left guide sleeve and the right guide sleeve are both provided with front end steps, the front ends of the left limit push rod and the right limit push rod are both provided with push rod shoulders, and the disc spring is located between the front end step of the corresponding guide sleeve and the corresponding push rod shoulder, the disc spring is used to keep the corresponding limit push rod and the corresponding pressure-bearing hardening pad in continuous contact.

[0011] In one possible implementation: the control processing unit is connected to the left servo motor driver and the right servo motor driver, and the control processing unit is also connected to the left magnetic scale reader and the right magnetic scale reader; the control processing unit is used to receive the injection molding machine's mold closing position signal, injection start signal, holding pressure start signal, and mold opening permission signal, and is also used to receive the injection speed segment and holding pressure segment number of the injection molding machine; the control processing unit is connected to the human-machine interface, and the human-machine interface is used to input the target coating thickness, allowable eccentricity, maximum clearance, initial preload position, holding pressure release cycle time, and insert type.

[0012] A plastic-coated injection molding process for preventing eccentricity includes the following steps: S1. Place the insert in the positioning area formed by the molding end face of the side slider and the cavity insert, drive the left limit push rod and the right limit push rod to press the left pressure hardening pad and the right pressure hardening pad respectively, and establish a pre-tightened state for both. S2. After the mold is closed, the control processing unit confirms the fitting state of the left limit push rod and the right limit push rod. During the injection stage, the position change of the left limit push rod and the right limit push rod is collected by the position detection component, and a preset displacement fluctuation range is set. S3. The control processing unit forms an eccentric state feature sequence based on the order of occurrence, strength and continuous trend of left and right position changes. It extracts the side with the larger displacement increment that crosses the preset displacement fluctuation range earlier to determine the side with stronger pressure and the side with weaker pressure among the left and right sides. It also determines the left and right retraction order and differential retraction range based on the target plastic coating thickness, maximum retraction amount, width of the slider forming end face and center distance between the left limit push rod and the right limit push rod. S4. Within the pressure holding and retraction window, the control processing unit drives the left lead screw drive assembly and the right lead screw drive assembly to move the limit push rod on the side with stronger pressure in sequence or to move the limit push rods on both sides synchronously backward. At the end of the pressure holding period, the backward movement stops or a return action is performed with a retraction distance less than the amount retracted in this cycle.

[0013] In one possible implementation: step S3 includes the following steps: determining the eccentricity state characteristic sequence: defining the side closer to the gating gate on the cavity insert as the gating side, and defining the opposite side as the far gating side; if the eccentricity state characteristic sequence shows that the pressure on the gating side is greater than that on the far gating side, then the gating side limit push rod is moved backward first. If the eccentricity characteristic sequence shows that the pressure on the gate side is equal to the pressure on the far gate side, then control the left limit push rod and the right limit push rod to move backward in the same direction and by the same amount; if the difference between the left and right retreat positions exceeds the set allowable eccentricity threshold and continues to increase, then stop increasing the difference retreat and limit the overall retreat to the maximum retreat amount.

[0014] The present invention has the following beneficial effects: 1. This invention uses left and right limiting push rods to abut against the pressure-bearing hardened pads at both ends of the lateral slider. A position detection component acquires the push rod position changes to form an eccentric state characteristic sequence. The control processing unit then controls the left and right lead screw drive components to perform differential yielding. This transforms the passive swaying caused by uneven melt impact in traditional injection molding into a dynamically adjustable active support process. While maintaining the controlled posture of the slider molding end face, a reasonable yield space is formed, effectively reducing the probability of simultaneous occurrence of product coating thickness dispersion, insert bias, and local flash, thus improving molding quality.

[0015] 2. This invention utilizes the dovetail guide rail and the dovetail groove at the bottom of the lateral slider for restricted guidance, and dynamically adjusts the yielding order and magnitude according to the eccentric state characteristic sequence during the molding process; when one side is under greater pressure, the push rod on that side is controlled to yield first; when the pressure is balanced, the same direction and amount of yielding occur; if the difference increases and does not converge, the overall yielding magnitude is limited; with the independent differential control of the left and right push rods, this invention only allows the slider to make minute attitude adjustments within the existing guide rail gap, avoiding support instability caused by excessive yielding, and effectively meeting the consistency manufacturing requirements of high-precision composite components. Attached Figure Description

[0016] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the overall external structure of the device; Figure 2 This is a schematic diagram of the cross-sectional structure of the mold body; Figure 3 This is a partial structural diagram of the guide sleeve; Figure 4 This is an assembly diagram of a pressure-hardening pad; Figure 5 This is a schematic diagram of the lead screw drive assembly; Figure 6 This is a schematic diagram of the side slider structure; Figure 7 This is a flowchart of a plastic injection molding process for preventing eccentricity according to the present invention.

[0017] In the diagram: 1. Mold body; 2. Fixed mold part; 3. Moving mold part; 4. Cavity insert; 5. Side stepped surface; 6. Slider support seat; 7. Dovetail guide rail; 8. Side slider; 9. Dovetail groove; 10. Forming end face; 11. Pressure-bearing back side; 12. Left pressure-bearing hardening pad; 13. Right pressure-bearing hardening pad; 14. Left limit push rod; 15. Right limit push rod; 16. Left lead screw drive assembly; 17. Right lead screw drive assembly; 18. Left guide sleeve; 19. Right guide sleeve; 20. Flange; 21. Oil reservoir ring groove; 22. Shallow concave positioning surface; 23. Shoulder plate; 24. Disc spring; 25. Push rod shoulder; 26. 27. Slider return spring; 28. Left lead screw nut seat; 29. ​​Left lead screw; 30. Left servo motor; 31. Right lead screw nut seat; 32. Right lead screw; 33. Right servo motor; 34. Lead screw bearing seat; 35. Axial bearing; 36. Coupling; 37. Linear guide rail; 38. Guide key; 39. Mechanical limit part; 40. Left magnetic scale slider; 41. Right magnetic scale slider; 42. Left magnetic scale reading head; 43. Right magnetic scale reading head; 44. Clamping ring; 45. Bracket; 46. Position detection assembly; 47. Control processing unit; 48. Left servo motor driver; 49. Right servo motor driver; 40. Human-machine interface. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described and explained in detail below with reference to the accompanying drawings and embodiments.

[0019] Example 1: A plastic-coated injection molded anti-eccentric slider positioning structure includes: Mold body 1, with cavity insert 4, side slider 8 and slider support 6 on it. The slider support 6 is fixed to the side step surface 5 of the mold body 1 and is provided with a dovetail guide rail 7; the bottom of the side slider 8 is provided with a dovetail groove 9 that slides with the dovetail guide rail 7, and the gap between the two on one side is 0.03 to 0.08 mm. The two ends of the lateral slider 8, which are close to and away from the cavity insert 4, are respectively provided with a molding end face 10 and a pressure-bearing back face 11. The pressure-bearing back face 11 is fixed with a left pressure-bearing hardening pad 12 and a right pressure-bearing hardening pad 13. The outer side of the slider bearing seat 6 is provided with a left limiting push rod 14 and a right limiting push rod 15, which are used to abut against the left pressure hardening pad 12 and the right pressure hardening pad 13, respectively. The left limit push rod 14 and the right limit push rod 15 are respectively connected to the left lead screw drive assembly 16 and the right lead screw drive assembly 17; The slider support 6 is provided with a position detection component 45 and a control processing unit 46. The position detection component 45 is used to detect the position of the left limit push rod 14 and the right limit push rod 15. The control processing unit 46 is used to form an eccentric state characteristic sequence that characterizes the slider swing trend based on the order of occurrence, strength of change and continuous trend of the position changes of the left limit push rod 14 and the right limit push rod 15, and control the left lead screw drive component 16 and the right lead screw drive component 17 to perform differential yielding.

[0020] Combination Figure 1 and Figure 2 As shown, the mold body 1 can be composed of a fixed mold part 2 and a moving mold part 3. The cavity insert 4 is installed on the fixed mold part 2, and the slider support 6 is installed on the lateral step surface 5 of the moving mold part 3. The lateral slider 8 retains only the reciprocating freedom along the normal direction of the forming side wall after cooperating with the dovetail guide rail 7 through the dovetail groove 9. The single-sided clearance is limited to 0.03mm to 0.08mm, which is used to suppress the attitude drift caused by guide looseness while ensuring smooth sliding. The molding end face 10 of the side slider 8 is used to define the side coverage contour of the insert. The pressure-bearing back surface 11 forms two independent pressure-bearing references through the left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13. The left limit push rod 14 and the right limit push rod 15 apply support force to the two pressure-bearing references respectively. The left lead screw drive assembly 16 and the right lead screw drive assembly 17 drive the corresponding push rod to generate controllable displacement respectively. The position detection assembly 45 continuously acquires the displacement change of the two push rods during the molding cycle. The control processing unit 46 combines the order, increment, and holding trend of the left and right displacement changes into an eccentric state feature sequence. In this embodiment, the eccentric state feature sequence represents the tendency of the slider to swing around the guide gap after being impacted by the melt, rather than a single pressure value or a single displacement value. The input source of the eccentric state feature sequence is the position of the left limit push rod 14, the position of the right limit push rod 15, and the injection molding machine process stage signal at the corresponding time. The control processing unit 46 first takes the left and right push rod positions after the mold is closed and the initial pre-tightening is completed as the reference position, and then continuously calculates the left displacement increment and right displacement increment relative to the reference position at each sampling time, and records the time when the two first exceed the displacement noise band. The displacement noise band is used to eliminate invalid small changes caused by mechanical micro-vibration, lubricating film fluctuation and sensor sampling jitter. Its upper limit can be one to three times the peak value of normal no-load reciprocating sampling, and it is written into the control processing unit 46 during machine adjustment. The control processing unit 46 forms an eccentric state characteristic sequence according to three layers of logic: sequential, strong and weak, and continuous. Sequential is used to determine which side enters the effective pressure response, strong and weak is used to compare the magnitude of the displacement increment or displacement change rate on both sides within the same process stage, and continuous is used to determine whether the left and right displacement difference is expanding, maintaining or converging. The resulting eccentric state feature sequence outputs a set of executable judgment results, namely, left-side priority retreat, right-side priority retreat, or simultaneous retreat on both sides, and the corresponding difference level, rather than just outputting abstract labels; the eccentric state feature sequence does not rely on unpublished training samples or uninterpretable statistical models, and its logical structure includes process stage alignment, reference position establishment, noise band filtering, left and right response feature extraction, eccentric state judgment, and retreat action mapping in sequence. The process stage alignment is used to prevent the direct mixing and comparison of displacement changes in different injection speed sections or holding pressure sections; the left and right displacement increments and their change rates after noise band filtering are entered into the response feature extraction stage; when the time difference, displacement increment difference and change rate difference of both sides are within the equivalent range obtained by machine adjustment, it is determined that both sides are under pressure simultaneously; when at least one of them continuously exceeds the corresponding equivalent range and the duration reaches the set confirmation time, it is determined that the side corresponding to the direction of the excess is the side with stronger pressure. The equivalent interval and confirmation time are determined by the qualified trial molding cycle of similar inserts. The qualified trial molding cycle refers to the injection molding cycle in which the plastic coating thickness falls within the upper and lower limits of the design tolerance and there are no flash defects in the appearance. The equivalent interval is calibrated and calculated by the peak-to-peak value of the displacement noise band of the no-load reciprocating displacement within this cycle. It is also saved separately according to the injection speed segment and the holding pressure segment to avoid instantaneous disturbances triggering erroneous yielding. The overall physical causal relationship represented by the logic is as follows: After the melt forms an uneven effect on both sides of the forming end face 10 of the slider, it causes a slight elastic displacement difference in the corresponding pressure path. This displacement difference is transmitted through the left limit push rod 14 and the right limit push rod 15 and collected by the position detection component 45. The control processing unit 46 identifies the swaying trend of the lateral slider 8 in the existing guide gap, and then converts the identification result into the yielding sequence and yielding level that can be executed by the left and right drive components. The control processing unit 46 controls the left lead screw drive assembly 16 and the right lead screw drive assembly 17 to perform differential yielding based on the eccentric state characteristic sequence. This allows the side with a pressure value higher than the preset deviation threshold to obtain a yielding amount that is triggered earlier than the corresponding side or greater than the preset difference ratio. The side with a pressure value lower than the preset deviation threshold maintains posture support or performs a yielding amount that is less than the preset difference ratio. This transforms the passive sway in the traditional single rear gear structure into a measurable, calculable, and adjustable support adjustment process. With this structure, the slider retraction is no longer a synchronous release, but rather a clearance space corresponding to the melt flow state is formed under the condition that the orientation of the forming end face is controlled. This can reduce the probability of simultaneous occurrence of coating thickness dispersion, insert side bias and local flash. To unify the spatial relationship of each mechanical structure, the direction of the lateral slider 8 from the pressure back 11 toward the cavity insert 4 is taken as the forward direction, and the two sides along the width direction of the pressure back 11 are defined as the left and right sides respectively; the axes of the left limit push rod 14 and the right limit push rod 15 are both parallel to the extension direction of the dovetail guide rail 7 and are at the same installation height, and the front end abutting surfaces of the two push rods are parallel to the pressure bearing surfaces of the corresponding pressure hardening pads respectively; When the left and right push rods perform equal displacement, they are used to drive or support the lateral slider 8 to make overall translation. When performing differential displacement, the lateral slider 8 is only allowed to make slight attitude adjustments within the existing fit gap between the dovetail groove 9 and the dovetail guide rail 7. The lateral slider 8 is not forced to disengage from the inclined surface of the dovetail guide rail 7 as a yielding method. To meet the requirements of lateral extraction after mold opening and reset in the next cycle, two sets of slider reset springs 26 can be symmetrically arranged between the slider support seat 6 and the side slider 8. The action direction of the slider reset spring 26 is consistent with the extension direction of the dovetail guide rail 7. One end of the spring is supported on the slider support seat 6, and the other end is supported on the side slider 8, and it applies force in a direction away from the cavity insert 4. During the mold closing preparation stage, the left limit push rod 14 and the right limit push rod 15 push the lateral slider 8 forward and compress the slider return spring 26. During the mold opening stage, after the left limit push rod 14 and the right limit push rod 15 retract to the withdrawal position, the slider return spring 26 drives the lateral slider 8 to move backward along the dovetail guide rail 7. The two sets of slider return springs 26 adopt the same specifications and are symmetrically arranged relative to the center plane of the slider. Their resultant force is less than the initial preload of the left limit push rod 14 and the right limit push rod 15, so as to avoid the return springs forming additional left and right differences in the eccentric state characteristic sequence. In this embodiment, the eccentric state feature sequence is generated by rule-based judgment, rather than by neural networks, machine learning classifiers, or implicit data models with opaque internal processing mechanisms trained on large historical samples. The control processing unit 46 performs process stage reading, benchmark subtraction, noise band comparison, equivalent interval comparison, and action mapping in a preset order for each sampling moment. Therefore, when changing to other detection objects, the judgment logic is only portable if it still has the four structural prerequisites of lateral slider 8, independent left and right pressure-bearing paths, corresponding position detection signals, and differential yielding actuator. It cannot be established independently without the dual pressure-bearing benchmark and dual push rod positioning structure of this invention. The motion mapping is preferably performed using a decision table pre-written into the control processing unit 46: when the first overpass time of the left side is earlier than that of the right side and the left displacement increment is continuously within the preset high displacement threshold range, the output is left side priority retreat; when the first overpass time of the right side is earlier than that of the left side and the right displacement increment is continuously within the preset high displacement threshold range, the output is right side priority retreat; when the difference between the first overpass times of the left and right sides, the difference in displacement increments, and the difference in change rates do not exceed the corresponding equivalent range, the output is synchronous retreat; The thresholds in the judgment table are all derived from the test mold data obtained under the same mold, similar inserts, and the same injection molding machine process window. The establishment process is as follows: first, empty mold reciprocating sampling is performed to determine the noise band, and then continuous sampling of no less than ten qualified molding cycles is performed to determine the normal fluctuation boundary of the left and right displacement difference under each process stage. The boundary along with the confirmation time is written into the control processing unit 46 as the on-site benchmark parameter before the mold leaves the factory or after the mold is changed. The left lead screw drive assembly 16 includes a left servo motor 29, and the right lead screw drive assembly 17 includes a right servo motor 32. The prerequisite for using position changes to identify yaw trends is that within the corresponding sampling window, the left servo motor 29 and the right servo motor 32 are in a motion state where their positions are maintained or not greater than a preset low-speed correction threshold, and the control processing unit 46 has not yet issued a new active differential yield command to the left lead screw drive assembly 16 and the right lead screw drive assembly 17. Under this premise, the left and right displacement increments collected mainly reflect the reaction of the melt, the elastic compression of the pressure path, and the attitude adjustment within the existing fit gap, without directly incorporating the inertial displacement during the large acceleration and deceleration of the motor, the rapid reversal of the lead screw, and the mold opening and extraction process into the eccentric state feature sequence. If the injection molding machine stage signal shows that it has entered the mold opening permission stage, or if the movement speed of any drive component exceeds the preset low speed correction threshold, the control processing unit 46 will pause updating the eccentricity strength judgment based on the data of that period and only retain the safety retreat or reset control. The logic for setting the preset low-speed correction threshold is as follows: extract the maximum command following speed of the drive component in the normal no-load cycle test, and superimpose the set safety ratio coefficient to determine it, which is used to accurately identify the active displacement disturbance of the equipment; thus, the eccentric state feature sequence corresponds to the force response characterization in the molding and pressing stage, rather than interpreting all dynamic displacements indiscriminately as slider sway. In this embodiment, the control processing unit 46 only performs limited state determination on the relative displacement change of the left and right push rods, the comparison results of the same stage, and the duration. It does not establish a pressure field distribution, melt viscosity field, or three-dimensional attitude full model beyond the range of the detection signal. Therefore, the calculation target of the eccentric state characteristic sequence is limited to identifying which side is compressed first, which side is compressed more strongly, and whether the difference is continuous, rather than inverting all fluid parameters from the two displacement signals. For any given cycle, if neither the left nor right displacement signal exceeds the noise band, or if it exceeds the noise band but does not meet the set confirmation time, then the cycle will only output a conservative action of maintaining pretension or synchronous small yielding, and will not output an amplified single-sided priority yielding command, so as to ensure that the software judgment complexity is consistent with the amount of information that the hardware can measure. In this embodiment, the position detection component 45 includes at least a left magnetic scale reader 41 and a right magnetic scale reader 42 for detecting displacement. To enable this embodiment to be directly programmed and implemented, the control processing unit 46 preferably performs the following steps in a fixed scanning cycle: reading the injection molding machine process stage signal; reading the current position of the left magnetic scale reader 41 and the right magnetic scale reader 42; and determining whether the current moment is within the allowed recognition window. If it is within the allowed recognition window, calculate the left and right displacement increments relative to the reference position, perform noise band filtering, and update the first crossover time, increment level, and duration time for the left and right sides; if it is not within the allowed recognition window, simply maintain or reset the execution state without refreshing the eccentricity strength judgment; output the action code for maintaining pre-tightening, left-side priority retreat, right-side priority retreat, or synchronous retreat according to the judgment table corresponding to the current process stage, and simultaneously output the corresponding differential level and total retreat upper limit; Action codes can be stored using discrete state numbering, and differential levels can be set to four levels: level 0, level 1, level 2, and level 3. Level 0 corresponds to maintaining pre-tightening or small synchronous yielding, while levels 1 to 3 correspond to progressively increasing unilateral priority yielding. Thus, the algorithm input, intermediate processing quantities, and output commands all have definite data objects in the software, rather than merely remaining at the conceptual description level. In this embodiment, the correspondence between the aforementioned beneficial effects and technical means is defined as follows: the restricted guiding cooperation of the dovetail guide rail 7 and the dovetail groove 9, the independent pressure-bearing structure of the double push rod pressed against the left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13, and the position detection component 45 jointly support the effect of identifying the slider sway trend; the left and right differential yielding executed by the control processing unit 46 based on the eccentric state characteristic sequence jointly support the effect of reducing the probability of simultaneous occurrence of coating layer thickness dispersion, insert side bias, and local flash; and the switchable execution mode of equal displacement and differential displacement of the left and right push rods supports the effect of forming a yielding space under the condition of maintaining the controlled posture of the forming end face 10. The effects are all limited to improving the ability to control defects or reducing their probability of occurrence. They are not described as necessarily eliminating flash, unevenness, or uneven pressure under any working condition, so as to avoid exaggerating the improvement that can be reasonably achieved by the structure and control measures into an absolute result. The preferred method for verifying the above effects is to use comparative mold trials under the same mold, the same insert type, and the same injection molding machine process window: one group uses synchronous or fixed retreat rhythm of left and right push rods, and the other group uses the differential retreat of the eccentric state characteristic sequence of this embodiment; the left and right displacement curves, final retreat amount, plastic coating thickness detection value, and flash or bias conditions are recorded for no less than ten consecutive qualified cycles and no less than ten consecutive boundary cycles for both groups. When evaluating, at least the following indicators should be compared: First, the difference between the maximum and minimum values ​​at the cross-section of the plastic coating thickness test; Second, whether the thickness deviation on the left and right sides exceeds the tolerance range determined by the trial mold; Third, the frequency of occurrence of local flash, missing glue, and side damage to inserts. If, after adopting this implementation method, one or more of the above indicators converge or decrease, it can be verified that the measurable, calculable, and adjustable support adjustment logic in this implementation method has engineering significance for improving molding quality; if the improvement range is different under different insert categories, the on-site mold test results of the corresponding category shall be used as the applicable basis for the parameter group of that category.

[0021] Combination Figure 4 The left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13 are located in the left and right halves of the pressure-bearing back side 11, respectively. The front and rear positions of the left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13 are the same, and the vertical height of the left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13 is the same. Both the left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13 are hardened steel blocks, and both the left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13 are fixedly connected to the side slider 8 by countersunk screws.

[0022] The pressure-bearing back surface 11 can be processed into a flat reference surface. The left pressure-bearing hardening pad 12 is arranged in the left half of the reference surface, and the right pressure-bearing hardening pad 13 is arranged in the right half of the reference surface. The projection positions of the two in the slider movement direction are consistent, and the installation height in the vertical direction is consistent, so that the attitude influence of the two pressure points on the forming end face 10 is within the same geometric reference. The left pressure-bearing hardening pad 12 and the right pressure-bearing hardening pad 13 are made of hardened steel blocks, whose surface hardness is higher than that of the side slider 8 body material. This is used to reduce the accumulation of indentations caused by repeated contact of the push rod and to avoid inconsistent contact stiffness between the left and right sides after long-term use. The head of the countersunk screw is embedded in the hardening pad and does not protrude from the pressure-bearing surface to ensure that the front end of the limit push rod forms a stable surface contact with the pressure-bearing hardening pad. When the front and rear positions are consistent and the top and bottom heights are consistent, the displacement difference fed back by the left and right push rods mainly reflects the difference in force, and no longer includes the geometric error caused by installation misalignment. Therefore, the eccentric state characteristic sequence formed by the control processing unit 46 is comparable. If there is a front-to-back deviation or height deviation between the hardened pad on one side and the other side, the left and right push rods may produce different displacement responses even if they are subjected to the same force, which may easily cause the control processing unit 46 to misjudge the assembly error as melt eccentricity. This embodiment improves the long-term consistency of the pressure bearing reference by symmetrically setting and wear-resistant fixing of the two hardened pads.

[0023] Combination Figure 6 A shallow concave positioning surface 22 adapted to the shape of the insert is provided on the molding end face 10, and the edge of the shallow concave positioning surface 22 is rounded; the angle between the inclined surfaces on both sides of the dovetail guide rail 7 is 60°. After the cavity insert 4 and the side slider 8 are closed, a cavity for molding the plastic-coated part is formed. The dovetail guide rail 7 is used to restrict the side slider 8 to reciprocate in a direction perpendicular to the side wall of the plastic-coated part.

[0024] The molding end face 10 can be machined into a shallow concave positioning surface 22 according to the outer contour of the insert to be plastic-coated. The depth of the shallow concave positioning surface 22 is less than the corresponding wall thickness of the insert, so that it can bear the functions of side limiting and local support, without excessively wrapping the insert. The edge of the shallow concave positioning surface 22 is rounded to reduce the edge stress concentration when the insert is pressed in and the slider slightly retracts, and to reduce the scratches on the surface of the metal insert and the local defects formed by the stagnation of the plastic melt in the sharp corner area. The angle between the inclined surfaces on both sides of the dovetail guide rail 7 is set to 60°. This angle is used to balance the guiding rigidity and processing feasibility, so that the lateral slider 8 can stably fit the inclined surface of the guide rail when subjected to the reaction force from the cavity direction. Since the dovetail structure restricts both vertical lifting and lateral movement, the lateral slider 8 only moves back and forth in a direction perpendicular to the side wall of the plastic-coated part. Therefore, the displacement changes fed back by the left limit push rod 14 and the right limit push rod 15 can directly correspond to the force response of the slider in the forming direction, and will not be masked by irrelevant directional movement. After the shallow concave positioning surface 22 and the 60° dovetail guide rail 7 work together, on the one hand, the consistency of insert placement is improved, and on the other hand, a single main motion direction is provided for eccentricity identification, which makes it easier for the control processing unit 46 to calculate the amount of retraction.

[0025] Combination Figure 3 The left limiting push rod 14 passes through the left guide sleeve 18, and the right limiting push rod 15 passes through the right guide sleeve 19. Both the left guide sleeve 18 and the right guide sleeve 19 are fixedly connected to the outer side of the slider bearing seat 6 through the flange 20. The gap between the inner hole of the left guide sleeve 18 and the right guide sleeve 19 and the outer circle of the corresponding limiting push rod is 0.02mm to 0.06mm. Both the inner hole of the left guide sleeve 18 and the right guide sleeve 19 are provided with an oil storage ring groove 21, which is filled with high temperature resistant grease.

[0026] Both the left limiting push rod 14 and the right limiting push rod 15 adopt a cylindrical straight rod structure, which are respectively inserted into the left guide sleeve 18 and the right guide sleeve 19. The guide sleeves are fixed to the outer side of the slider bearing seat 6 by the flange 20, so that the axis of the push rod is consistent with the direction of slider movement. The fit clearance between the inner hole of the guide sleeve and the outer circle of the push rod is controlled between 0.02mm and 0.06mm, which is used to retain the necessary lubricating film thickness under high frequency reciprocating, while limiting the contact deviation caused by the tilt of the push rod. The front end of the guide sleeve is provided with an oil storage ring groove 21, which is filled with high-temperature resistant grease. During the movement of the push rod, the grease forms a stable lubrication layer along the inner hole surface, which can reduce the fluctuation of frictional resistance and the displacement lag caused by abrasive intrusion. The flange 20 fixing structure also facilitates the disassembly and replacement of the guide sleeve. After long-term use, the guiding accuracy can be restored by replacing the guide sleeve, without having to reconstruct the slider bearing seat 6 body. For eccentricity detection, the guide sleeve not only supports the push rod, but also constrains the displacement response of the push rod within the linear axial range, reducing the false displacement caused by push rod wobbling, thereby improving the repeatability of the data collected by the position detection component 45.

[0027] Combination Figure 5 The left lead screw drive assembly 16 includes a left lead screw nut seat 27, a left lead screw 28, and a left servo motor 29. The rear end of the left limit push rod 14 is fixedly connected to the left lead screw nut seat 27. The left lead screw 28 is threadedly engaged with the left lead screw nut seat 27, and the rear end of the left lead screw 28 is connected to the left servo motor 29. The right lead screw drive assembly 17 includes a right lead screw nut seat 30, a right lead screw 31, and a right servo motor 32. The rear end of the right limit push rod 15 is fixedly connected to the right lead screw nut seat 30. The right lead screw 31 is threadedly engaged with the right lead screw nut seat 30, and the rear end of the right lead screw 31 is connected to the right servo motor 32. The left lead screw 28 and the right lead screw 31 have the same pitch, and both the left lead screw 28 and the right lead screw 31 are trapezoidal threaded lead screws.

[0028] The rear end of the left limit push rod 14 is rigidly connected to the left lead screw nut seat 27, and the rear end of the right limit push rod 15 is rigidly connected to the right lead screw nut seat 30. The left lead screw 28 and the left lead screw nut seat 27 are engaged by a trapezoidal thread, and the right lead screw 31 and the right lead screw nut seat 30 are engaged by a trapezoidal thread. The left servo motor 29 and the right servo motor 32 drive the corresponding lead screws to rotate, converting the rotational displacement into the axial linear displacement of the push rod. The pitch of the left lead screw 28 and the right lead screw 31 is set to the same parameter, so that when the control processing unit 46 issues equal pulses or equal position commands, the left and right push rods have a consistent theoretical displacement conversion relationship, which makes it easy to directly associate the differential retraction amount with the slider attitude correction amount; the trapezoidal thread lead screw has a high load-bearing capacity and self-locking capacity, which can reduce the passive retraction caused by external reaction force during the pressure holding stage. The lead screw nut seat can be installed on the linear support member outside the bearing seat, so that it only makes axial displacement and does not rotate with the lead screw, thereby ensuring that the push rod end face and the pressure hardening pad maintain planar contact; compared with the structure using a single drive linkage, the left and right independent lead screw drives can respectively perform three types of actions: holding, yielding and micro-returning. The control processing unit 46 can individually correct either side according to the eccentric state characteristic sequence, so that the yielding action corresponds to the pressure state; During specific assembly, the left lead screw 28 and the right lead screw 31 are respectively inserted into the lead screw bearing seats 33 fixed on the outside of the slider support seat 6. Each lead screw is axially positioned with the corresponding lead screw bearing seat 33 through a pair of axial bearing bearings 34. The rear end of the lead screw is connected to the output shaft of the corresponding servo motor through a coupling 35, so that the reaction force transmitted from the slider to the limit push rod is borne by the lead screw bearing seat 33 and does not directly act on the output shaft of the servo motor. The left lead screw nut seat 27 and the right lead screw nut seat 30 are respectively slidably engaged with the linear guide rail 36 or guide key 37 arranged along the axial direction of the push rod to limit the rotation of the lead screw nut seat with the lead screw and keep the lead screw nut seat, the limit push rod and the corresponding guide sleeve coaxial. Mechanical limit parts 38 are respectively provided within the front and rear stroke ranges of the lead screw nut seat. The front mechanical limit part 38 is used to prevent the push rod from moving too far forward and squeezing the lateral slider 8, and the rear mechanical limit part 38 is used to prevent the retraction stroke from exceeding the effective meshing length between the lead screw and the nut seat. The mechanical limit stroke is greater than the normal control stroke but not greater than the maximum safe stroke allowed by the equipment, thereby avoiding the drive component from tripping or structural collision when abnormal commands or position feedback failure occur.

[0029] The position detection component 45 includes a left magnetic ruler slider 39, a right magnetic ruler slider 40, a left magnetic ruler reading head 41, and a right magnetic ruler reading head 42. The left magnetic ruler slider 39 is fixed to the outer circle of the left limit push rod 14 by a clamping ring 43, and the right magnetic ruler slider 40 is fixed to the outer circle of the right limit push rod 15 by a clamping ring 43. The left magnetic ruler reading head 41 and the right magnetic ruler reading head 42 are both fixedly connected to the slider support 6 by a bracket 44. The left magnetic ruler reading head 41 and the left magnetic ruler slider 39 maintain a parallel gap, and the right magnetic ruler reading head 42 and the right magnetic ruler slider 40 maintain a parallel gap.

[0030] The left magnetic ruler slider 39 and the right magnetic ruler slider 40 are respectively clamped and fixed to the outer circle of the corresponding limit push rod by clamping ring 43. The clamping ring 43 adopts a split clamping structure, so that the surface of the push rod does not need to be additionally slotted or drilled. The left magnetic ruler reading head 41 and the right magnetic ruler reading head 42 are fixed to the slider support seat 6 by rigid bracket 44. The bracket 44 is provided with adjustment holes to keep the measurement direction of the reading head parallel to the movement direction of the push rod. A set parallel gap is maintained between the reading head and the magnetic ruler slider. This gap is locked after adjustment to ensure stable output of displacement signal. In this embodiment, the magnetic scale structure is used to directly measure the linear displacement of the push rod relative to the bearing seat without indirect conversion through motor coding feedback. Therefore, it can reflect the influence of lead screw drive clearance, elastic deformation, and pressure rebound on the push rod position. After the control processing unit 46 reads the displacement data of the left magnetic scale reading head 41 and the right magnetic scale reading head 42, it can form a displacement increment sequence, a displacement difference sequence, and a displacement holding sequence to distinguish between states such as stable fit, unilateral bias, and bilateral synchronous pressure. After using independent magnetic ruler detection, even if the left servo motor 29 and the right servo motor 32 execute the same command, the control processing unit 46 can still identify whether the push rod position is consistent, thereby avoiding misjudgment caused by the inconsistency between the execution end and the force end; the displacement changes collected by the position detection component 45 in the injection identification stage mainly include the small elastic displacement and gap elimination amount formed by the limit push rod, the lead screw nut pair, the lead screw axial support and the pressure contact part under the reaction of the melt, and do not take the unrestrained free retreat of the limit push rod as the premise of eccentric identification; During machine adjustment, after the empty mold is closed and the initial pre-tightening is completed, the same graded pre-tightening displacement is applied to the left and right push rods respectively. The deviation between the magnetic ruler displacement and the servo command position at each stage is recorded to obtain the reference response range of the left and right pressure paths. When there is a fixed difference in the reference response on both sides, the control processing unit 46 first performs zero-point and fixed deviation compensation, and then compares the incremental changes in the injection stage. The sampling window and the drive retraction window of the eccentric state characteristic sequence are set separately in time: before the retraction command is issued, the change of the magnetic scale is used to identify the eccentric load of the melt; after the retraction command is issued, the control processing unit 46 distinguishes the command displacement and the residual deviation that continues to be generated relative to the command position from the actual displacement of the magnetic scale, and uses it to determine whether the left and right difference is converging or expanding after the retraction. The effective resolution of the magnetic scale reading head should be less than the upper limit of the displacement noise band used. If the pressure response on both sides does not exceed the effective resolution range in multiple consecutive molding cycles, or if the data on the same side jumps, is lost, or exceeds the range, the control processing unit 46 marks the eccentric state characteristic sequence of this cycle as invalid, does not increase the differential yield based on this, and keeps the left and right push rods in a safe position or runs according to the preset synchronous yielding rhythm, thereby avoiding misinterpreting the unmeasurable signal as the slider force state. The preferred on-site deployment steps for the position detection component 45 include: after the reader is installed, perform a low-speed reciprocating motion within the full stroke of the push rod to check for range interruptions and gap interference in the output of the left and right reader heads; sample for no less than twenty reciprocating cycles under empty mold and no injection conditions, record the peak-to-peak fluctuations of the left and right channels, and use the larger one as the basis for setting the noise band; then, under the condition of inserting the target insert and using formal injection molding process parameters, select no less than ten continuous molding cycles that are qualified in appearance and size, and save the left and right displacement curves of the injection stage and the holding pressure stage as the on-site benchmark data for this insert category; The preferred criteria for judging the appearance and dimensions include: no visible flash, no wall thickness exceeding tolerance or uneven distribution, and the plastic coating thickness of the corresponding test section falling within the tolerance range confirmed by the trial mold; only periodic data that meets these criteria are written into the baseline data group to avoid mistaking the abnormal displacement curves corresponding to non-conforming parts as normal templates; the baseline data group is not used to train the classification model, but to determine the zero-point compensation value, noise band upper limit, equivalent interval, and confirmation time; For the same insert category, after replacing the magnetic scale reading head, reinstalling and disassembling the push rod, adjusting the guide sleeve, or changing the initial preload position on the left and right, the above field deployment steps should be repeated to update the effective reference parameters of the position detection component 45, so as to ensure that the data collected under different maintenance conditions can still be directly used for the same set of judgment rules. To avoid misinterpreting the displacement superposition caused by the active movement of the drive mechanism as pressure off-center load, this embodiment preferably processes the read head data according to two sources: one is the command-following displacement that is in the same direction and at the same beat as the servo position command and is within the preset execution tolerance; the other is the additional displacement that is out of the command beat and continues to exist within the confirmation time. The control processing unit 46 only participates in the determination of the strength and continuity trend of the eccentricity of the latter. For any sampling moment, if a momentary spike that coincides with the motor commutation moment appears simultaneously on both the left and right sides, and the spike does not last longer than the confirmation time, it is regarded as a drive commutation disturbance and is removed in this judgment. Therefore, the position detection component 45 outputs not the undifferentiated total displacement, but the effective response displacement after stage screening and source stripping, so as to ensure that under dynamic working conditions with screw drive backlash, servo fine adjustment and structural elastic rebound, the eccentricity recognition is still based on the repeatable pressure response. This embodiment limits the use of the position detection component 45 to comparing the relative changes of the left and right channels within the same process stage, rather than requiring the magnetic ruler to reconstruct the absolute posture of the slider with high precision; therefore, the read head's resolution capability only needs to be able to stably distinguish between three states: not crossing the noise band, crossing the noise band, and whether the difference between crossing the band continues to increase. Since the judgment is based on the relative increment under the same period, stage, and structural reference, as long as the guide clearance, the small reverse travel of the lead screw and the elastic compression of the bearing component are included in the empty mold noise band and the field reference parameters, the judgment logic will not fail, and it is not required to introduce additional laser interferometers, ultrasonic time delay probes or other high-precision measurement sensors to recover the subtle attitude quantities that cannot be directly measured.

[0031] A shoulder plate 23 is provided above the lateral slider 8. The shoulder plate 23 is fixedly connected to the slider support 6. The vertical gap between the lower surface of the shoulder plate 23 and the upper surface of the lateral slider 8 is 0.05mm to 0.12mm. The front ends of the left guide sleeve 18 and the right guide sleeve 19 are both provided with front end steps. The front ends of the left limit push rod 14 and the right limit push rod 15 are both provided with push rod shoulders 25. The outer periphery of the front ends of the left limit push rod 14 and the right limit push rod 15 are both fitted with disc springs 24. The disc springs 24 are located between the front step of the guide sleeve and the push rod shoulders 25. The disc springs 24 are used to keep the corresponding limit push rod and the corresponding pressure-bearing hardened pad in continuous contact.

[0032] The shoulder plate 23 is fixed to the upper part of the slider support 6, and a vertical gap of 0.05mm to 0.12mm is maintained between its lower surface and the upper surface of the lateral slider 8. This gap is used to allow the slider to slide freely under normal lubrication and thermal expansion conditions, while providing lifting restriction when subjected to eccentric upward force. As a result, the abnormal posture changes of the slider are mainly constrained in the plane, and the displacement difference processed by the control processing unit 46 is closer to the true yaw trend. Disc springs 24 are respectively fitted around the front ends of the left limit push rod 14 and the right limit push rod 15. The disc springs 24 are located between the front end step of the guide sleeve and the push rod shoulder 25. During assembly, the disc springs 24 are in a pre-compression state. This pre-compression state makes the front end of the push rod continuously press against the pressure-bearing hardening pad. Even if the screw reverses or the melt pressure fluctuates, the end face of the push rod is not easy to detach from the pressure-bearing surface. In this embodiment, the main purpose of the disc spring 24 is to maintain contact continuity rather than to provide the driving force for the slider to retract. Therefore, its stiffness should be higher than that of a general return spring to reduce measurement distortion caused by the compression absorption of the spring itself. After the pressure plate 23 and the disc spring 24 work together, the vertical warping of the slider is restricted, the contact continuity of the push rod is maintained, and the interpretation conditions of the left and right displacement data are more stable.

[0033] The control processing unit 46 is connected to the left servo motor driver 47 and the right servo motor driver 48, and is also connected to the left magnetic scale reader 41 and the right magnetic scale reader 42. The control processing unit 46 is used to receive the injection molding machine's mold closing position signal, injection start signal, pressure holding start signal, and mold opening permission signal, and is also used to receive the injection speed segment and pressure holding segment number of the injection molding machine. The control processing unit 46 is connected to the human-machine interface 49, which is used to input the target coating thickness, allowable eccentricity, maximum clearance, initial preload position, pressure holding release cycle, and insert type.

[0034] The control processing unit 46 can be an industrial controller. The left servo motor driver 47 and the right servo motor driver 48 are used to execute the displacement or speed commands issued by the control processing unit 46. The left magnetic scale reading head 41 and the right magnetic scale reading head 42 feed back the push rod position to the control processing unit 46. After receiving the mold closing position signal, the control processing unit 46 calls the initial pre-tightening position parameters to drive the left and right push rods into the unified bonding reference; after receiving the injection start signal and injection speed segment number, it records the conditions for the occurrence of displacement changes of the left and right push rods; after receiving the pressure holding start signal and pressure holding segment number, it switches the control target from attitude recognition to yielding release and final stage holding; after receiving the mold opening permission signal, it drives the left and right push rods back to the standby position. The target plastic coating thickness input in the human-machine interface 49 is used to determine the overall yielding intention in this cycle. The allowable eccentricity is used to limit the upper limit of the left and right displacement difference. The maximum yield is used to limit the safety release boundary. The pressure holding and release cycle is used to limit the displacement change rate in each control segment. The insert type is used to call the pre-stored pre-tightening difference and release priority parameters. In this embodiment, the insert category represents the process identity related to the insert metal thickness, occlusion area and outer contour, rather than simply a record field; by summarizing the injection molding machine status signal, position detection data and process input parameters into the same control processing unit 46, the left and right retreat actions can correspond to the process stages within the molding cycle, avoiding the need to execute a single retreat distance based on a fixed program. The logical functions of the above input parameters in this embodiment are further defined as follows: the plastic coating thickness target refers to the design thickness value or corresponding thickness group value from the outer surface of the insert to the target molding surface of the coating layer. The control processing unit 46 does not directly use this value to close the loop for thickness measurement, but uses it as the process basis for determining the upper limit of the overall clearance space. For the same type of mold, when the plastic coating thickness target is large, the allowable overall clearance space can be increased accordingly, and when the plastic coating thickness target is small, the overall clearance space should be tightened accordingly. The allowable degree of eccentricity refers to the upper limit of the displacement difference between the left and right push rods under the current insert category and the current process stage. The upper limit is used to distinguish between acceptable attitude fine-tuning and abnormal sway that may cause the coating layer to be too thick or too thin. The determination method can be: taking the stable qualified sample obtained by trial molding as the benchmark, statistically analyzing the normal fluctuation range of the left and right displacement difference within the corresponding period, and then reserving a safety margin outside the range to form the allowable degree of eccentricity. The maximum allowable amount refers to the safety boundary of the total amount of backward movement of the left and right push rods within a single cycle. Its physical meaning is to ensure that the slider still maintains effective guiding contact and the forming end face 10 is effectively limited. This parameter can be determined by the smaller of the following three values: the allowable release space of the shallow concave positioning surface 22, the effective stroke of the lead screw, and the upper limit of the process without generating flash. The initial pre-tightening position refers to the target position when the left and right push rods establish a unified contact reference after the mold is closed. The position is determined by the condition that the left pressure hardening pad 12 and the right pressure hardening pad 13 are stably pressed against each other and the disc spring 24 enters the pre-tightening state, but the side slider 8 has not yet undergone obvious forward deformation. It can be determined by repeatedly taking stable contact points in the empty mold and then superimposing the predetermined pre-tightening displacement. The pressure holding and release cycle refers to the combination of parameters of the start time, duration and displacement change rate of each yielding action during the pressure holding stage. It is used to avoid the push rod moving too far backward too early in the initial stage of pressure holding, which would cause instability, and also to avoid the release lag in the final stage of pressure holding, which would lose the purpose of posture adjustment. The insert category is used to classify inserts of different sizes, different gate relative positions and different plastic coating areas into preset process groups. After identifying the insert category, the control processing unit 46 calls the initial preload position, allowable eccentricity, maximum yield amount and gate side priority corresponding to the process group. The control processing unit 46 processes the above parameters in the following order: first, it loads the parameter group according to the insert type; then, it establishes a zero-point reference based on the initial pre-tightening position; during the injection and holding pressure processes, it compares the left and right displacement differences with the allowable eccentricity in real time, and simultaneously compares the cumulative yield amount with the maximum yield amount; only when the maximum yield amount is not exceeded is it allowed to perform left, right, or synchronous yielding according to the holding pressure release cycle; thus, each parameter has a clear physical meaning and plays the roles of reference establishment, anomaly judgment, boundary limitation, and cycle constraint in the control process. The parameter groups in the human-machine interface 49 are preferably established by on-site trial molding calibration rather than by automatic generation through a general learning model: For each insert category, first select a stable process window of the target mold on the injection molding machine used in formal production, continuously mold for several cycles and retain the data of the qualified cycles; then the operator manually judges the cycle results based on the appearance of the sample, the thickness of the plastic coating and whether the insert positioning is offset, and writes the left and right displacement data, process stage number and final yield execution result corresponding to the qualified cycle into the parameter group of the insert category; The preferred criteria for manual judgment include: the plastic coating thickness meets the design requirements or the corresponding thickness group requirements; flash and insufficient glue are within acceptable range; and there are no pressure marks or obvious off-center load marks on the insert edges. When the control processing unit 46 calls the parameter group, it only performs threshold comparison, stage switching, and yielding action mapping, without performing self-learning updates. When the mold is changed, the gate position is adjusted, the insert shape and size are changed, or the holding pressure process window is changed, the operator shall re-perform on-site trial molding calibration and overwrite the original parameter group. Therefore, the data processing path of the control processing unit 46 always remains a traceable chain of engineering rules: the injection molding machine stage signal limits the comparison range, the magnetic scale displacement data provides the left and right response, the insert type determines the threshold parameter set, and the final output is the displacement command and cycle command of the left and right drive components, rather than an uninterpretable probability value or implicit weight. In this embodiment, the control processing unit 46 is limited to four functions: stage triggering, threshold comparison, state determination, and displacement command issuance. These functions can be accomplished using a conventional industrial controller, a programmable logic controller extension module, or a motion control unit with equivalent real-time processing capabilities. Its calculations do not include numerical simulation of the melt flow field, nor do they include adaptive model updates that rely on large-scale sample training. Since the core control quantity of this invention is the relative displacement difference and cumulative yielding amount of the left and right push rods in a specific process stage, the system complexity matches the problem being solved. In order to make the data flow relationship between each module clear, the control processing unit 46 preferably sets up an input refresh area, a rule judgment area, a parameter call area and an output distribution area. The input refresh area is used to receive the position values ​​of the left magnetic scale reader 41 and the right magnetic scale reader 42, the injection molding machine stage signal, and the current position and speed feedback of the servo driver; the rule judgment area is used to complete the benchmark subtraction, noise band comparison, equivalent interval comparison, confirmation time accumulation, and eccentricity status update. The parameter call area is used to load the initial preload position, allowable eccentricity, maximum clearance, pressure holding release cycle time, and gate side priority of the category according to the insert type; the output sending area is used to convert the judgment result into the target position increment, speed limit value, and execution enable state of the left servo motor driver 47 and the right servo motor driver 48; thus, the data source, processing process, and destination are separated in the software structure, which is convenient for those skilled in the art to implement by module; The above signal connection methods can be implemented using industrial interfaces commonly used in this field: the injection molding machine mold closing position signal, injection start signal, pressure holding start signal, and mold opening permission signal can be implemented using switch input or fieldbus input; the injection speed segment number and pressure holding segment number can be transmitted using register mapping values, bus data words, or other known digital quantities. The position values ​​of the left magnetic scale reading head 41 and the right magnetic scale reading head 42 can be read using the serial position interface, analog quantity acquisition interface or bus position interface supported by the controller; the displacement or speed command of the servo drive can be issued using pulse command method, communication bus method or other known motion control method; Communication protocols and electrical interfaces are conventional selection criteria in this field. As long as the control processing unit 46 can simultaneously obtain stage signals, position feedback and drive status feedback within one scan cycle, the rule determination and action mapping of this embodiment can be realized. The control processing unit 46 preferably operates according to a fixed cycle, which can be selected from 5ms to 20ms based on the magnetic scale reading head refresh speed and the servo driver response speed; within each cycle, input acquisition, stage judgment, eccentricity status update, boundary verification and instruction output are completed sequentially; If the current cycle detects that the mold opening permission signal is established, any driver alarms, any position channel is out of range, or any position channel is lost for more than a set number of consecutive times, the eccentricity strength update is skipped directly and the safety control branch is entered, so that the left and right push rods maintain their current positions, return to safe positions, or run according to the preset reset cycle; thus, the real-time requirements are limited to the range that can be met by conventional industrial controllers and servo systems, and it is not required to use an ultra-high computing power processing platform. The human-machine interface 49 and the control processing unit 46 preferably adopt an interaction method that separates the parameter table and the status page: the parameter table is used to write the insert type, allowable eccentricity, maximum clearance, initial preload position and pressure holding release cycle; the status page is used to display the current process stage, the current left and right positions, the left and right displacement difference, the current eccentricity status, the current clearance mode and the cumulative clearance. After the operator modifies the parameters, the control processing unit 46 preferably loads the new parameters only before the start of the next molding cycle to avoid inconsistent judgment criteria caused by switching thresholds midway through the same cycle. This clarifies the specific boundaries of human-computer interaction and avoids vague descriptions lacking technical implementation paths, such as automatic interaction and seamless connection.

[0035] Example 2: Combination Figure 7 As shown, a plastic injection molding process for preventing eccentricity includes the following steps: S1. Place the insert in the positioning area formed by the molding end face 10 of the side slider 8 and the cavity insert 4, drive the left limit push rod 14 and the right limit push rod 15 to press the left pressure hardening pad 12 and the right pressure hardening pad 13 respectively, and establish a pre-tight state for both. S2. After the mold is closed, the control processing unit 46 confirms the fitting state of the left limit push rod 14 and the right limit push rod 15. During the injection stage, the position detection component 45 collects the position changes of the left limit push rod 14 and the right limit push rod 15 and sets the preset displacement fluctuation range. S3. The control processing unit 46 forms an eccentric state feature sequence based on the order of occurrence, strength and continuous trend of left and right position changes, extracts the side with larger displacement increment and earlier crossing the preset displacement fluctuation range, in order to determine the side with stronger pressure and weaker pressure among the left and right sides, and determines the left and right retraction order and differential retraction range based on the target plastic coating thickness, maximum retraction amount, width of slider forming end face 10 and center distance of left limit push rod 14 and right limit push rod 15. S4. Within the pressure holding and yielding window, the control processing unit 46 drives the left lead screw drive assembly 16 and the right lead screw drive assembly 17 to move the limit push rod on the side with stronger pressure in sequence or to move the limit push rods on both sides synchronously backward. At the end of the pressure holding period, the backward movement stops or a return action is performed with a yielding distance less than the yielding amount in this cycle. The positioning structure used in this embodiment is further provided with a shallow concave positioning surface 22 and a disc spring 24. The shallow concave positioning surface 22 is used to form a positioning reference for the side of the insert, and the disc spring 24 is used to maintain the continuous contact between the limiting push rod and the pressure hardening pad, so that steps S1 to S4 have stable loading conditions and position acquisition conditions. In one molding cycle, after the insert is placed in the positioning area composed of the shallow concave positioning surface 22 and the cavity insert 4, the left limiting push rod 14 and the right limiting push rod 15 move forward under the action of the driving component and press the left pressure hardening pad 12 and the right pressure hardening pad 13. The disc spring 24 enters the pre-compression state to form a uniform contact starting point. After the mold is closed, the control processing unit 46 reads the starting position and holding status of the left and right push rods fed back by the position detection component 45 to confirm whether there is any misfitting, foreign matter inclusion, or pre-tightening abnormality. During the injection stage, the left and right push rods may produce different displacement responses under the action of the melt. The control processing unit 46 collects their position change sequence and defines the order of occurrence as the pressure start difference, the strength of the change as the displacement increment difference, and the continuous trend as the expansion or convergence state of the displacement difference. The plastic coating thickness target is used to constrain the overall clearance space, the maximum clearance amount is used to limit the safety release boundary, the width of the slider forming end face 10 and the center distance between the left limit push rod 14 and the right limit push rod 15 are used together to convert the differential clearance into the posture correction amount of the forming end face 10; after entering the pressure holding clearance window, if the left and right displacement changes are similar, the control processing unit 46 sends a synchronous backward movement command to the left and right drive components; if the pressure enhancement on one side is more obvious, the control processing unit 46 sends a priority backward movement command to the drive component on that side, while the other side maintains or performs a smaller backward movement amount; During the final stage of pressure holding, when the position change enters the stable range, the control processing unit 46 stops moving backward. If the priority yielding side still retains a yield difference exceeding the allowable eccentricity relative to the other side after stopping the backward movement, and its slight rebound can reduce the left and right position difference, then a slight rebound less than the yielding amount in this cycle is performed on the priority yielding side. If the left and right position difference expands after the rebound attempt, then the continued rebound is immediately canceled and the current position is maintained. This process transforms the slider retraction process from a fixed process to a process of periodic state adjustment by establishing a correspondence between structural action, displacement acquisition, and retraction calculation. The positioning area formed by the shallow concave positioning surface 22 and the cavity insert 4 in step S1 refers to the insert installation space jointly defined by the two after the mold is closed. It does not require the insert to contact the shallow concave positioning surface 22 and the cavity insert 4 simultaneously when the mold is in a fully open state. During placement, the lateral slider 8 is driven to the mounting position in the mold-open state, and the insert is placed against the shallow concave positioning surface 22. The insert is temporarily held by the positioning pin, elastic pressure plate or vacuum suction hole provided on the moving mold part 3. The mold is closed, so that the cavity insert 4 approaches the insert from the other side and completes the final positioning together with the shallow concave positioning surface 22. The temporary holding component avoids the plastic coating molding contour setting. Its holding force is only used to prevent the insert from falling off or shifting before the mold is closed, and allows the insert to make limited micro-correction when the cavity insert 4 approaches. After confirming that the insert has entered the final positioning state, the left limit push rod 14 and the right limit push rod 15 establish pre-tightening support or maintain the pre-tightening support that has already been established, thereby avoiding the misunderstanding that the common positioning area that does not exist when the fixed mold part 2 and the moving mold part 3 are in a separated state is a solid space that must be formed at the same time during the assembly. The calculation logic in step S3 can be executed in the following order: the control processing unit 46 reads the target coating thickness and the maximum allowable allowance, and determines the overall allowable allowance range in this cycle in combination with the current insert type; the upper limit of the overall allowance range is not greater than the maximum allowance, and the lower limit is zero or the minimum effective release amount set by the process. Based on the eccentric state characteristic sequence obtained during the injection stage, the control processing unit 46 determines that the current cycle belongs to one of the three basic modes: left-side priority retreat, right-side priority retreat, or synchronous retreat. After determining the basic mode, the control processing unit 46 compares the difference in displacement increment or displacement change rate between the left and right sides and converts it into a difference level. The higher the difference level, the more obvious the uneven pressure on both sides, and the larger the retreat share that can be allocated to the priority retreat side. The control processing unit 46 uses the width of the slider forming end face 10 and the center distance between the left limit push rod 14 and the right limit push rod 15 to check whether the differential clearance will cause the posture of the forming end face 10 to exceed the limit; wherein, the center distance between the left limit push rod 14 and the right limit push rod 15 is used to characterize the slider deflection trend corresponding to the given differential displacement, and the width of the slider forming end face 10 is used to characterize the contour position change formed by the deflection trend at the edge of the forming end face 10. For the same left-right differential displacement, the smaller the center distance of the push rods, the more obvious the slider deflection trend; the larger the width of the forming end face 10, the more obvious the change in the contour position at the edge of the forming end face 10; therefore, when the width of the forming end face 10 is large or the center distance of the push rods is small, the allowable differential clearance should be tightened; when the width of the forming end face 10 is small and the center distance of the push rods is large, the differential clearance can be appropriately widened within the allowable eccentricity and maximum clearance range. Based on this, the control processing unit 46 first determines the total yield amount, and then allocates the total yield amount between the left and right sides: when yielding synchronously, the allocation is the same on both sides; when yielding with priority on one side, the priority side first obtains the main share, and the other side obtains zero or a small compensation share; specifically, the total yield amount D is determined based on the plastic coating thickness target and the maximum yield amount, the yield range of the priority side is set as D×K1, and the yield range of the non-priority side is set as D×K2, where the proportional coefficient K1>K2 and K1+K2=1, and the specific value of K1 is positively correlated with the absolute value of the displacement increment difference in the eccentric state characteristic sequence according to a preset mapping; the specific positive correlation preset mapping rule is as follows: K1 = 0.5 + 0.5 × (absolute value of current displacement increment difference / set allowable eccentricity threshold) If the calculated priority side yield amount, the other side yield amount, or the sum of the two exceeds the maximum yield amount, the control processing unit 46 truncates the total amount according to the maximum yield amount and prioritizes ensuring that the attitude support side still retains the minimum support displacement. Whether to perform a slight back-off at the end of the pressure holding phase is also determined by the same data flow: first, check whether the left and right position difference still exceeds the allowable eccentricity after the backward movement stops; then, determine the priority back-off side that forms the position difference based on the eccentricity state characteristic sequence and the back-off record of this cycle; only when the total back-off amount does not touch the safety boundary and the back-off of the priority back-off side can reduce the left and right position difference, will a back-off correction smaller than the back-off amount of this cycle be applied to that side. During the retracement process, the left and right position differences before and after correction are continuously compared. The retracement stops when the allowable eccentricity is reached. The retracement also stops when the position difference shows an increasing trend. This avoids excessive retracement on the weaker side without feedback, which would further amplify the slider attitude deviation. Therefore, step S3 does not directly output a single value, but sequentially completes the total amount determination, mode determination, difference allocation, attitude verification, and boundary truncation, and finally sends the calculation results to the drive execution stage of step S4. The attitude check based on the width of the slider forming end face 10 and the center distance between the left limit push rod 14 and the right limit push rod 15 is applicable under the premise that the lateral slider 8 still maintains effective contact with the dovetail guide rail 7, and the left and right differential clearance is only used for minor attitude adjustment within the existing guide gap; under this premise, the control processing unit 46 regards the left and right clearance difference as the attitude correction indication under small displacement conditions, and uses it to compare the relative magnitude of the change in the edge contour of the forming end face 10 by different differential schemes, rather than interpreting it as a free attitude change after the slider rotates at a large angle or leaves the guide rail; When the calculation results indicate that a certain differential scheme may cause insufficient guide rail fit reserve on either side, abnormal exhaustion and elimination of the gap of the shoulder plate 23, or that continued backward movement of the priority retreat side at this stage will lead to the attitude check exceeding the limit, the control processing unit 46 will abandon further amplification of the differential level and instead reduce the differential level or switch to synchronous retreat; thus, the retreat calculation in step S3 corresponds to the micro-correction environment under guidance constraints, rather than the unconstrained rigid body swing environment, thereby avoiding the use of large pose assumptions that do not hold under complex dynamic working conditions for the execution judgment of this process; To make the program implementation boundaries of steps S3 and S4 clearer, the control processing unit 46 preferably enters the pre-tightening confirmation state, injection identification state, pressure holding execution state, final correction state and mold opening reset state sequentially in each molding cycle; in the pre-tightening confirmation state, it only checks whether the left and right push rods have reached the initial pre-tightening position and whether the difference between the left and right positions is within the allowable installation error range; if not, the amplified differential yield instruction is not given in this cycle. In the injection identification state, only the eccentricity state feature sequence is updated, and a large backward movement is not immediately executed; in the holding pressure execution state, left-side priority retreat, right-side priority retreat, or synchronous retreat is implemented according to the retreat mode and differential level output in step S3; in the final correction state, only stopping further backward movement or performing a small amount of back-up is allowed; in the mold opening and reset state, the injection identification data of this cycle is no longer used to determine the strength of eccentricity; thus, the functional boundaries between each step are clear, avoiding the disordered superposition of identification logic and execution logic at the same time; In step S3, the left and right retraction order and differential retraction range are calculated based on the target plastic coating thickness, maximum retraction amount, width of the slider forming end face 10, and center distance between the left limit push rod 14 and the right limit push rod 15. In this embodiment, a preset decision table is preferred instead of a complex online solution. The decision table includes at least three types of input items: first, an eccentricity mode input item, used to indicate left-side priority, right-side priority, or synchronous retraction; second, a differential level input item, used to indicate whether the pressure difference is mild, moderate, or severe; and third, a geometric constraint input item, used to call the corresponding differential upper limit according to the grouping of the slider forming end face 10 width and the grouping of the center distance between the left limit push rod 14 and the right limit push rod 15. The output items of the decision table should include at least the total concession amount, the concession share of the priority side, the concession share of the non-priority side, and whether entry into the final micro-rebound is allowed; in this way, those skilled in the art can directly establish parameter tables and decision tables based on the insert category without having to reverse-engineer the hidden model not disclosed in the specification. During on-site molding trials, it is preferable to divide the same type of insert into two groups under the same process window: a control process and the current process. The control process uses a fixed synchronous retreat or a single fixed retreat cycle, while the current process uses the eccentricity identification and differential retreat process from step S1 to step S4. Both groups record at least the same number of continuous molding cycles and compare the plastic coating thickness, insert side offset marks, and flash at the same inspection section. The plastic coating thickness can be detected using calipers, plug gauges, cross-section thickness measurement, or other methods commonly used in the field. Offset marks and flash can be determined by visual inspection combined with dimensional verification. If the position difference between the left and right push rods converges faster than the control process at the end of the pressure holding stage under this process, and the thickness dispersion range of the corresponding sample decreases or the frequency of abnormal appearance decreases, then the causal chain between data acquisition, state recognition and execution action can be used to verify that this process has an engineering feasible effect. The above verification method is used to illustrate the evaluation criteria and comparison path of this process, and does not require that the same improvement be obtained in every use case.

[0036] Step S3 includes the following steps: Determine the eccentricity state characteristic sequence: Define the side closest to the gating gate on the cavity insert 4 as the gating side and the opposite side as the far gating side; If the eccentricity state characteristic sequence shows that the pressure on the gating side is greater than that on the far gating side, then prioritize controlling the gating side limit push rod to move backward. If the eccentricity characteristic sequence shows that the pressure on the gate side is equal to the pressure on the far gate side, then control the left limit push rod 14 and the right limit push rod 15 to move backward in the same direction and by the same amount; if the difference between the left and right retreat positions exceeds the set allowable eccentricity threshold and continues to increase, then stop increasing the difference retreat and limit the overall retreat to the maximum retreat amount.

[0037] In step S3, the control processing unit 46 defines the side adjacent to the gate as the gate side and the other side as the far gate side, and judges the eccentric state characteristic sequence state based on the timing and amplitude of the left and right position changes; when the displacement increment of the gate side appears first and is continuously higher than that of the far gate side, the control processing unit 46 determines that the gate side is under greater pressure, issues a priority backward movement command to the gate side drive component, and maintains the current position of the push rod on the far gate side, so as to retain the attitude reference of the other side while relieving local pressure. When the displacement increment on the far gate side exceeds that on the gate side in the subsequent stage and remains there, the control processing unit 46 determines that the flow extrusion has been transferred to the far gate side and changes to prioritize releasing the far gate side; if the displacement increment, rate of change and holding trend on both sides are within the set equivalent range, it is determined that the pressure is approximately balanced, and the left and right push rods are controlled to move backward in the same direction and amount to form an overall material replenishment space. When the left-right difference continues to expand and does not converge, the control processing unit 46 determines it as an abnormal attitude expansion trend. At this time, it stops increasing the difference yield and uses the maximum yield as the total release limit, allowing safe yielding only within this limit. This processing method allows the abnormal limit to be executed directly based on the attitude change trend, rather than based on a single pressure or a single displacement threshold. Therefore, it can shrink the control action range before the yaw expands to affect the coating quality.

[0038] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A plastic-coated injection-molded anti-eccentric slider positioning structure, comprising: The mold body (1) is provided with a cavity insert (4), a side slider (8) and a slider support seat (6), characterized in that: The slider support (6) is fixed to the side step surface (5) of the mold body (1) and is provided with a dovetail guide rail (7); the bottom of the side slider (8) is provided with a dovetail groove (9) that slides with the dovetail guide rail (7), and the gap between the two on one side is 0.03 to 0.08 mm; The side slider (8) has a molding end face (10) and a pressure back face (11) at its two ends close to and away from the cavity insert (4), respectively. The pressure back face (11) is fixed with a left pressure hardening pad (12) and a right pressure hardening pad (13). The outer side of the slider bearing seat (6) is provided with a left limiting push rod (14) and a right limiting push rod (15), which are used to abut against the left pressure hardening pad (12) and the right pressure hardening pad (13), respectively. The left limit push rod (14) and the right limit push rod (15) are respectively connected to the left lead screw drive assembly (16) and the right lead screw drive assembly (17). The slider support (6) is provided with a position detection component (45) and a control processing unit (46). The position detection component (45) is used to detect the position of the left limit push rod (14) and the right limit push rod (15). The control processing unit (46) is used to form an eccentric state characteristic sequence that characterizes the slider swing trend based on the order of occurrence, strength and continuous trend of the position changes of the left limit push rod (14) and the right limit push rod (15), and control the left lead screw drive component (16) and the right lead screw drive component (17) to perform differential yielding.

2. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 1, characterized in that: The left pressure-bearing hardening pad (12) and the right pressure-bearing hardening pad (13) are located in the left and right halves of the pressure-bearing back side (11), respectively. The front and rear positions of the left pressure-bearing hardening pad (12) and the right pressure-bearing hardening pad (13) are the same, and the vertical height of the left pressure-bearing hardening pad (12) and the right pressure-bearing hardening pad (13) is the same. The left pressure-bearing hardening pad (12) and the right pressure-bearing hardening pad (13) are both hardened steel blocks. The left pressure-bearing hardening pad (12) and the right pressure-bearing hardening pad (13) are both fixedly connected to the side slider (8) by countersunk screws.

3. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 1, characterized in that: The molding end face (10) is provided with a shallow concave positioning surface (22) that matches the shape of the insert, and the edge of the shallow concave positioning surface (22) is provided with rounded corners; the angle between the inclined surfaces on both sides of the dovetail guide rail (7) is 60°, and the cavity insert (4) and the side slider (8) form a cavity for molding the plastic-coated part after the mold is closed, and the dovetail guide rail (7) is used to restrict the side slider (8) from reciprocating in a direction perpendicular to the side wall of the plastic-coated part.

4. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 1, characterized in that: The left limiting push rod (14) passes through the left guide sleeve (18), and the right limiting push rod (15) passes through the right guide sleeve (19). The left guide sleeve (18) and the right guide sleeve (19) are both fixedly connected to the outer side of the slider support seat (6) through the flange (20). The gap between the inner hole of the left guide sleeve (18) and the right guide sleeve (19) and the outer circle of the corresponding limiting push rod is 0.02mm to 0.06mm. The inner hole of the left guide sleeve (18) and the right guide sleeve (19) is provided with an oil storage ring groove (21), and the oil storage ring groove (21) is filled with high temperature resistant grease.

5. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 1, characterized in that: The left lead screw drive assembly (16) includes a left lead screw nut seat (27), a left lead screw (28), and a left servo motor (29). The rear end of the left limit push rod (14) is fixedly connected to the left lead screw nut seat (27). The left lead screw (28) is threadedly engaged with the left lead screw nut seat (27). The rear end of the left lead screw (28) is connected to the left servo motor (29). The right lead screw drive assembly (17) includes a right lead screw nut seat (30), a right lead screw (31), and a right servo motor (32). The rear end of the right limit push rod (15) is fixedly connected to the right lead screw nut seat (30). The right lead screw (31) is threadedly engaged with the right lead screw nut seat (30). The rear end of the right lead screw (31) is connected to the right servo motor (32). The left lead screw (28) and the right lead screw (31) have the same pitch. Both the left lead screw (28) and the right lead screw (31) are trapezoidal threaded lead screws.

6. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 1, characterized in that: The position detection component (45) includes a left magnetic ruler slider (39), a right magnetic ruler slider (40), a left magnetic ruler reading head (41), and a right magnetic ruler reading head (42). The left magnetic ruler slider (39) is fixed on the outer circle of the left limit push rod (14) by a clamping ring (43), and the right magnetic ruler slider (40) is fixed on the outer circle of the right limit push rod (15) by a clamping ring (43). The left magnetic ruler reading head (41) and the right magnetic ruler reading head (42) are both fixedly connected to the slider support seat (6) by a bracket (44). The left magnetic ruler reading head (41) and the left magnetic ruler slider (39) maintain a parallel gap, and the right magnetic ruler reading head (42) and the right magnetic ruler slider (40) maintain a parallel gap.

7. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 4, characterized in that: A shoulder plate (23) is provided above the lateral slider (8). The shoulder plate (23) is fixedly connected to the slider support (6). The vertical gap between the lower surface of the shoulder plate (23) and the upper surface of the lateral slider (8) is 0.05mm to 0.12mm. The front ends of the left guide sleeve (18) and the right guide sleeve (19) are both provided with front end steps; the front ends of the left limit push rod (14) and the right limit push rod (15) are both provided with push rod shoulders (25), and disc springs (24) are sleeved on the outer periphery of the front ends of the left limit push rod (14) and the right limit push rod (15). The disc springs (24) are located between the front end steps of the guide sleeve and the push rod shoulders (25). The disc springs (24) are used to keep the corresponding limit push rods and the corresponding pressure-bearing hardening pads in continuous contact.

8. The anti-eccentricity slider positioning structure for plastic injection molding according to claim 6, characterized in that: The control processing unit (46) is connected to the left servo motor driver (47) and the right servo motor driver (48), and the control processing unit (46) is connected to the left magnetic scale reader (41) and the right magnetic scale reader (42). The control processing unit (46) is used to receive the injection molding machine mold closing position signal, injection start signal, pressure holding start signal and mold opening permission signal, and to receive the injection speed segment and pressure holding segment number of the injection molding machine. The control processing unit (46) is connected to the human-machine interface (49), and the human-machine interface (49) is used to input the plastic coating thickness target, allowable eccentricity, maximum clearance, initial pre-tightening position, pressure holding release cycle and insert type.

9. A plastic-coated injection molding process for preventing eccentricity, applied to the plastic-coated injection molding anti-eccentric slider positioning structure described in claim 1, characterized in that: Includes the following steps: S1. Place the insert in the positioning area formed by the molding end face (10) of the side slider (8) and the cavity insert (4), drive the left limit push rod (14) and the right limit push rod (15) to press the left pressure hardening pad (12) and the right pressure hardening pad (13) respectively, and establish a pre-tight state for both. S2. After the mold is closed, the control processing unit (46) confirms the fitting state of the left limit push rod (14) and the right limit push rod (15). During the injection stage, the position change of the left limit push rod (14) and the right limit push rod (15) is collected by the position detection component (45), and a preset displacement fluctuation range is set. S3, the control processing unit (46) forms an eccentric state feature sequence based on the order of occurrence, strength and continuous trend of the left and right position changes, extracts the side with the larger displacement increment and the earlier one that crosses the preset displacement fluctuation range, in order to determine the side with stronger pressure and the side with weaker pressure among the left and right sides, and determines the left and right retraction order and differential retraction range based on the target plastic coating thickness, maximum retraction amount, width of the slider forming end face (10) and center distance between the left limit push rod (14) and the right limit push rod (15); S4. Within the pressure holding and yielding window, the control processing unit (46) drives the left lead screw drive assembly (16) and the right lead screw drive assembly (17) to move the limit push rod on the side with stronger pressure in sequence or to move the limit push rods on both sides synchronously backward. At the end of the pressure holding period, the backward movement stops or a return action is performed with a yielding distance less than the yielding amount in this cycle.

10. The anti-eccentricity molding process for plastic injection molding according to claim 9, characterized in that: The step S3 includes the following steps: Determine the eccentric state characteristic sequence: Define the side of the gating gate close to the cavity insert (4) as the gating side and the opposite side as the far gating side; If the eccentric state characteristic sequence shows that the pressure on the gating side is greater than that on the far gating side, then prioritize controlling the gating side limit push rod to move backward. If the eccentricity state characteristic sequence shows that the pressure on the gate side is equal to the pressure on the far gate side, then control the left limit push rod (14) and the right limit push rod (15) to move backward in the same direction and amount; if the difference between the left and right retreat positions exceeds the set allowable eccentricity threshold and continues to increase, then stop increasing the difference retreat and limit the overall retreat to the maximum retreat amount.

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