A tie rod failure early warning method for injection molding machines

Abstract

The invention discloses a tie rod failure warning method for an injection molding machine, and relates to the field of injection molding machines. The method establishes a relationship function, and sets a tie rod failure warning parameter by using the normal elongation of the tie rod obtained by the relationship function during the mold adjustment process. The real-time stretching length of the tie rod is obtained at a preset interval during the operation of the injection molding machine. When the preset interval count is equal to a preset number of times, the average value of the real-time stretching length of the tie rod at the preset interval corresponding to the preset number of times is obtained. The difference between the real-time stretching length of the tie rod and the average value is obtained at the current mold of the injection molding machine as a tie rod elongation deviation value, and it is judged whether the tie rod elongation deviation value is greater than or equal to a target failure warning value. When the tie rod elongation deviation values ​​at consecutive preset times are all greater than or equal to the target failure warning value, an alarm is issued. The method solves the problem in the prior art that fatigue fractures of tie rods mostly occur suddenly and cannot be warned in advance.

Description

Technical Field

[0001] The invention relates to the field of injection molding machines, and in particular to a pull rod failure early warning method for injection molding machines. Background Art

[0002] The tie rod is an important part of the two-plate injection molding machine, which bears the tension generated by mold clamping and mold expansion. The tie rod continuously undergoes the cycle of mold clamping, mold expansion, and mold opening, and its stress is similar to a pulsating cycle. When the tie rod undergoes a high cycle, it may break when the stress of the tie rod is much less than the yield stress due to poor working conditions, insufficient design, material defects, etc. This situation is generally called fatigue fracture, which is also the most common failure form of the tie rod.

[0003] Most of the fatigue fractures of tie rods occur suddenly, and it is difficult to detect obvious features. The common feature is that the clamping cylinder cannot build pressure, but at this time the tie rod has already broken and there is no early warning, so the injection molding machine manufacturer cannot be notified in time to prepare and transport the goods, which leads to a longer time to replace the tie rod, which in turn greatly increases the downtime and has a great impact on production. Summary of the invention

[0004] In order to provide early warning of the breakage of the tie rod, the present invention proposes a tie rod failure warning method for an injection molding machine, comprising:

[0005] S1: Establish the relationship function between the normal elongation of the tie rod and the length of the stretched section of the tie rod and the clamping pressure difference;

[0006] S2: During the mold adjustment process, the length of the stretched section of the tie rod is obtained through the structural state of the mold clamping structure of the injection molding machine; the initial clamping pressure is set, and the clamping pressure difference between the initial clamping pressure and the corresponding clamping pressure at the end of the clamping is obtained, and the normal elongation of the tie rod is obtained by using the relationship function and the finite element analysis method through the length of the stretched section of the tie rod and the clamping pressure difference; the tie rod failure warning parameter is set according to the normal elongation of the tie rod to obtain the target failure warning value;

[0007] S3: During the operation of the injection molding machine and at the preset interval mold times, the difference between the mold locking position distance corresponding to the tie rod when the mold locking force reaches the initial mold locking pressure and the mold locking position distance corresponding to the tie rod at the end of mold locking is obtained as the real-time stretching length of the tie rod, and the preset interval mold times count is increased by 1;

[0008] S4: Determine whether the preset interval module count is equal to the preset number of times. If not, return to step S3. If so, obtain the average value of the real-time stretching length of the pull rod corresponding to the preset number of preset interval modules;

[0009] S5: Under the current mode of the injection molding machine, the difference between the real-time stretching length of the tie rod and the average value is obtained as the tie rod elongation deviation value, and it is determined whether the tie rod elongation deviation value is greater than or equal to the target failure warning value. If so, the warning count is increased by 1;

[0010] S6: In the next mold run of the injection molding machine, determine whether the tie rod elongation deviation value is greater than or equal to the target failure warning value. If so, the warning count is increased by 1 and the process proceeds to step S7; if not, the warning count is reset and the process returns to step S5;

[0011] S7: Determine whether the warning count is equal to the preset number of times. If so, issue an alarm. If not, return to step S6.

[0012] Furthermore, after step S7, the following steps are further included:

[0013] S8: Replace the mold or the tie rod, and after the replacement, return to step S2 to reset the tie rod failure warning parameters.

[0014] Furthermore, after resetting the pull rod failure warning parameter, it also includes adjusting it, and the adjustment method is:

[0015] Determine whether there is a mold in the preset mold interval whose tie rod elongation deviation value is less than or equal to the set error value before replacing the mold or the tie rod. If so, use the reset tie rod failure warning parameter as the target failure warning value; if not, obtain the average value of the tie rod elongation deviation value in the preset mold interval, and adjust the reset tie rod failure warning parameter by the average value to obtain the target failure warning value; the end point of the preset mold interval is the last mold of the injection molding machine before replacing the mold or the tie rod, and the starting point is the mold separated by the preset number of times from the last mold.

[0016] Furthermore, the specific method of adjusting the reset tie rod failure warning parameter by the average value is as follows:

[0017] Determine whether the average value satisfies the first determination condition, if so, adjust the tie rod failure warning parameter according to the first formula, if not, adjust the tie rod failure warning parameter according to the second formula;

[0018] The first judgment condition is: E<β′<(α-E), where β′ is the average value, E is the set error value, and α is the target failure warning value in the previous mold adjustment process;

[0019] The first formula is: α″=α′-α′ / α*β′, where α′ is the pull rod failure warning parameter obtained after reset, and α″ is the target failure warning value;

[0020] The second formula is: α″=α′-α′ / α*β′+E.

[0021] Furthermore, the expression of the relationship function is:

[0022] A 1 =(aL+b 1 +b 2 )P;

[0023] In the formula, a is the tie rod diameter coefficient, b is 1 is the flexibility coefficient of the mold structure, b 2 is the flexibility coefficient of the annular tooth on the tie rod, P is the clamping pressure difference, L is the length of the stretched section of the tie rod, A 1 It is the normal extension of the tie rod.

[0024] Furthermore, the value of the flexibility coefficient of the clamping structure and the value of the flexibility coefficient of the annular teeth on the pull rod are obtained by a finite element analysis method.

[0025] Furthermore, the mold clamping structure includes a tie rod, a fixed mold plate fixed on the tie rod, and a movable mold plate movably arranged on the tie rod, and the movable mold plate can move along the tie rod toward a side away from or close to the fixed mold plate;

[0026] The mold closing structure also includes a brake nut and a locking cylinder. The brake nut is located on the side of the movable template away from the fixed template, and the brake nut can engage the pull rod. The locking cylinder includes a cylinder barrel and a rear cover. The cylinder barrel is fixed on the side of the fixed template away from the movable template, and the rear cover is arranged on the end of the cylinder barrel away from the fixed template. A locking piston is arranged in the cylinder barrel, and the locking piston is connected to the pull rod.

[0027] Furthermore, a groove is provided at one end of the pull rod close to the locking piston, and an electronic ruler sensing block is provided in the groove; an electronic ruler is provided on the back cover, which passes through the locking piston groove and is communicated with the electronic ruler sensing block, and is used to obtain the vertical distance from the electronic ruler sensing block to the inner wall of the back cover during the mold closing process.

[0028] Furthermore, the brake nut and the locking piston are both provided with a plurality of teeth; the step S2 specifically comprises: obtaining the length of the stretched section of the tie rod through the structural state of the mold closing structure of the injection molding machine when the mold closing is completed, and the obtaining formula is:

[0029] L=L 1 +L 2 +H+L 3 +L 4 -L 5 -L 6 ;

[0030] Where, L 1L is the vertical distance from the first tooth position of the brake nut close to the moving platen to the moving platen when mold closing is completed; 2 is the thickness of the movable platen; H is the thickness of the mold set between the movable platen and the fixed platen; L 3 is the thickness of the fixed template; L 4 L is the vertical distance from the fixed template close to the rear cover to the inner wall of the rear cover; 5 It is the vertical distance from the first tooth position of the clamping piston close to the cylinder barrel to the electronic ruler sensor block when the mold is closed; L 6 It is the vertical distance from the electronic ruler sensing block to the inner wall of the rear cover when the mold is closed; and L is the length of the stretched section of the pull rod when the mold is closed.

[0031] Furthermore, the mold locking position distance is a vertical distance from the electronic ruler sensor block or the pull rod away from one end of the movable mold plate to the inner side wall of the rear cover.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] (1) The present invention establishes a relationship function between the normal elongation of the tie rod and the length of the stretched section of the tie rod and the clamping pressure difference, and uses the normal elongation of the tie rod obtained by the relationship function to set the tie rod failure warning parameter during the mold adjustment process, and obtains the real-time stretching length of the tie rod at a preset interval mold during the operation of the injection molding machine. When the preset interval mold count is equal to the preset number of times, the average value of the real-time stretching length of the tie rod at the preset interval mold corresponding to the preset number of times is obtained, and the difference between the real-time stretching length of the tie rod and the average value at the current mold of the injection molding machine is obtained as the tie rod elongation deviation value, and it is judged whether the tie rod elongation deviation value is greater than or equal to the target failure warning value. When the tie rod elongation deviation values ​​at consecutive preset times are all greater than or equal to the target failure warning value, an alarm is issued. By continuously judging the tie rod elongation deviation value at each mold, and using the judgment results of consecutive molds at a preset number of times as the basis for the alarm, the accuracy of the judgment is greatly improved, and misjudgment is avoided, thereby solving the problem that most of the fatigue fractures of the tie rod in the prior art occur suddenly and cannot be warned in advance;

[0034] (2) After the warning, the present invention further includes replacing the mold or the tie rod, and after the replacement, resetting the tie rod failure warning parameter, and further adjusting it after resetting, specifically: judging whether there is a mold in the preset mold interval whose tie rod elongation deviation value is less than or equal to the set error value before the mold or the tie rod is replaced, if so, taking the reset tie rod failure warning parameter as the target failure warning value; if not, obtaining the average value of the tie rod elongation deviation value in the preset mold interval, and adjusting the reset tie rod failure warning parameter by the average value to obtain the target failure warning value, by further adjusting the reset tie rod failure warning parameter, the target failure warning value is greatly refined, and the accuracy of the warning is further improved;

[0035] (3) The present invention improves the accuracy of the warning by setting the first judgment condition, the first formula and the second formula and adjusting the reset pull rod failure warning parameter using the average value. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A method flow chart of a tie rod failure early warning method for an injection molding machine;

[0037] Figure 2 The figure is the mold closing structure diagram;

[0038] Figure 3 This is a diagram showing the length of the stretched section of the tie rod on the mold closing structure.

[0039] In the figure: 1. Pull rod; 2. Fixed platen; 3. Cylinder barrel; 4. Locking piston; 5. Back cover; 6. Electronic ruler sensor block; 7. Electronic ruler; 8. Control module; 9. Alarm; 10. Finite element module; 11. Brake nut; 12. Moving platen; 13. Mold. DETAILED DESCRIPTION

[0040] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0041] Embodiment 1

[0042] In order to solve the problem that the fatigue fracture of the pull rod in the prior art mostly occurs suddenly and no early warning can be given, Figure 1 As shown, the present invention proposes a tie rod failure early warning method for an injection molding machine, comprising:

[0043] S1: Establish the relationship function between the normal elongation of the tie rod and the length of the stretched section of the tie rod and the clamping pressure difference;

[0044] It should be noted that the tie rod will stretch axially under the clamping pressure, and the elongation of the tie rod can be divided into two stages: First, under the same clamping pressure and fixed mold thickness, the elongation of the tie rod is almost unchanged. At this time, the tie rod does not undergo plastic deformation and there is no crack, which is the normal elongation stage. Suppose the normal elongation of the tie rod is A 1 ; 2. Cracks appear on the tie rod. Under the same clamping force and fixed mold thickness, the elongation of the tie rod increases rapidly, and with the increase in the number of operations, the cracks continue to expand until the tie rod is completely broken, which is the tie rod damage stage.

[0045] Because of factors such as gaps in the clamping structure, the starting position of clamping is usually difficult to locate. Therefore, the clamping position distance corresponding to the tie rod when the clamping force reaches the set initial clamping pressure P1 is taken as the initial measurement value S1, and the clamping position distance corresponding to the tie rod at the end of clamping is taken as the termination measurement value S2. The difference between the two is the elongation of the tie rod, that is, the real-time stretching length of the tie rod. The clamping pressure corresponding to the end position of clamping is P2, and P2-P1 is the clamping pressure difference P.

[0046] The expression of the relationship function is:

[0047] A 1 =(aL+b 1 +b 2 )P;

[0048] In the formula, a is the tie rod diameter coefficient, b is 1 is the flexibility coefficient of the mold structure, b 2 is the flexibility coefficient of the annular tooth on the tie rod, P is the clamping pressure difference, L is the length of the stretched section of the tie rod, A 1 It is the normal extension of the tie rod.

[0049] The value of the flexibility coefficient of the clamping structure and the value of the flexibility coefficient of the annular teeth on the pull rod are obtained by a finite element analysis method.

[0050] S2: During the mold adjustment process, the length of the stretched section of the tie rod is obtained through the structural state of the mold clamping structure of the injection molding machine; the initial clamping pressure is set, and the clamping pressure difference between the initial clamping pressure and the corresponding clamping pressure at the end of the clamping is obtained, and the normal elongation of the tie rod is obtained by using the relationship function and the finite element analysis method through the length of the stretched section of the tie rod and the clamping pressure difference; the tie rod failure warning parameter is set according to the normal elongation of the tie rod to obtain the target failure warning value;

[0051] In this embodiment, according to the measurement accuracy and the characteristics of the tie rod material itself, the tie rod failure warning parameter is preset to be in a certain ratio to the normal elongation of the tie rod.

[0052] S3: During the operation of the injection molding machine and at the preset interval mold times, the difference between the mold locking position distance corresponding to the tie rod when the mold locking force reaches the initial mold locking pressure and the mold locking position distance corresponding to the tie rod at the end of mold locking is obtained as the real-time stretching length of the tie rod, and the preset interval mold times count (whose initial value is 0) is increased by 1;

[0053] The clamping position distance is the vertical distance from the electronic ruler sensing block or the pull rod away from one end of the movable plate to the inner side wall of the rear cover.

[0054] S4: Determine whether the preset interval module count is equal to the preset number of times (the preset number of times in this step in this embodiment is set to 10). If not, return to step S3. If so, obtain the average value of the real-time stretching length of the pull rod under the preset number of preset interval modules corresponding to the preset number of times;

[0055] S5: Under the current mode of the injection molding machine, the difference between the real-time stretching length of the tie rod and the average value is obtained as the tie rod elongation deviation value, and it is determined whether the tie rod elongation deviation value is greater than or equal to the target failure warning value. If so, the warning count (whose initial value is 0) is increased by 1 and the next step is entered. If not, the next step is directly entered;

[0056] S6: In the next mold run of the injection molding machine, determine whether the tie rod elongation deviation value is greater than or equal to the target failure warning value. If so, the warning count is increased by 1 and the process proceeds to step S7; if not, the warning count is reset and the process returns to step S5;

[0057] S7: Determine whether the warning count is equal to a preset number of times (the preset number of times in this step in this embodiment is set to 10). If so, issue an alarm; if not, return to step S6.

[0058] In the actual production process, the mold needs to be replaced frequently, and the thickness of the mold changes, that is, the normal elongation A1 value of the tie rod under the same clamping pressure difference will change, and the corresponding tie rod failure warning parameter α value will also change. Assuming that the tie rod has been slightly damaged before the mold is replaced, that is, 0<tie rod elongation deviation value<α, then the new A1 value needs to be re-acquired after the mold is replaced. In addition, after the mold is replaced, the clamping pressure difference may change, which will also change the A1 value. Therefore, in the above cases, the tie rod failure warning parameters need to be reset.

[0059] The step S7 further includes:

[0060] S8: Replace the mold or the tie rod, and after the replacement, return to step S2 to reset the tie rod failure warning parameters.

[0061] After resetting the pull rod failure warning parameters, it also includes adjusting them. The adjustment method is:

[0062] Before replacing the mold or the tie rod, determine whether there is a mold in the preset mold interval whose tie rod elongation deviation value is less than or equal to the set error value. If so, take the reset tie rod failure warning parameter as the target failure warning value; if not, obtain the average value of the tie rod elongation deviation value in the preset mold interval, and adjust the reset tie rod failure warning parameter by the average value to obtain the target failure warning value; the end point of the preset mold interval is the final mold of the injection molding machine before replacing the mold or the tie rod, and the starting point of the interval is the mold separated by the preset number of times from the final mold. In this embodiment, the molds in the preset mold interval total 10 times.

[0063] The specific method of resetting the pull rod failure warning parameters by adjusting the average value is as follows:

[0064] Determine whether the average value satisfies the first judgment condition, if so, adjust the tie rod failure warning parameter according to the first formula, if not (β′≥α-E), adjust the tie rod failure warning parameter according to the second formula;

[0065] The first judgment condition is: E<β′<(α-E), where β′ is the average value, E is the set error value, and α is the target failure warning value in the previous mold adjustment process;

[0066] The first formula is: α″=α′-α′ / α*β′, where α′ is the pull rod failure warning parameter obtained after reset, and α″ is the target failure warning value;

[0067] The second formula is: α″=α′-α′ / α*β′+E.

[0068] The present invention improves the accuracy of early warning by setting the first judgment condition, the first formula and the second formula and adjusting the reset pull rod failure early warning parameter using the average value.

[0069] After the early warning, the present invention also includes replacing the mold or the tie rod, and after the replacement, resetting the tie rod failure early warning parameter, and further adjusting it after the resetting, specifically: judging whether there is a module in the preset module interval in which the tie rod elongation deviation value is less than or equal to the set error value before the mold or the tie rod is replaced, if so, taking the reset tie rod failure early warning parameter as the target failure early warning value; if not, obtaining the average value of the tie rod elongation deviation value in the preset module interval, and adjusting the reset tie rod failure early warning parameter by the average value to obtain the target failure early warning value, and further adjusting the reset tie rod failure early warning parameter, thereby greatly refining the target failure early warning value and further improving the accuracy of the early warning.

[0070] like Figure 2As shown, the mold clamping structure includes a tie rod 1, a fixed mold plate 2 fixed on the tie rod, and a movable mold plate 12 movably arranged on the tie rod 1, and the movable mold plate 12 can move along the tie rod 1 toward a side away from or close to the fixed mold plate 2;

[0071] The mold closing structure also includes a brake nut 11 and a locking cylinder. The brake nut 11 is located on the side of the movable template 12 away from the fixed template 2, and the brake nut 11 can engage the pull rod 1; the locking cylinder includes a cylinder barrel 3 and a rear cover 5. The cylinder barrel 3 is fixed on the side of the fixed template 2 away from the movable template 12, and the rear cover 5 is arranged on the end of the cylinder barrel 3 away from the fixed template 2. A locking piston 4 is provided in the cylinder barrel 3, and the locking piston 4 is connected to the pull rod 1.

[0072] The end of the pull rod 1 close to the mold locking piston 4 is provided with a groove, and an electronic ruler sensor block 6 is provided in the groove; the rear cover 5 is provided with an electronic ruler 7 that passes through the mold locking piston groove and is communicated with the electronic ruler sensor block 6, which is used to obtain the vertical distance from the end of the electronic ruler sensor block 6 or the pull rod away from the movable template to the inner wall of the rear cover during the mold closing process.

[0073] It should be noted that the clamping structure of the present invention is also connected to a control module 8, an alarm 9, and a finite element module 10, and the electronic ruler 7 in the clamping structure is communicatively connected to the control module 8; the electronic ruler 7 is specifically used to transmit the position information sensed by the electronic ruler sensor block 6 to the control module 8, and the control module 8 obtains the vertical distance from the electronic ruler sensor block 6 or the pull rod away from one end of the movable template to the inner wall of the rear cover during the clamping process according to the position information; the output end of the control module 8 is connected to the alarm 9; the control module 8 is also connected to the finite element module 10, and the finite element module 10 is used to obtain the value of the flexibility coefficient of the clamping structure and the value of the flexibility coefficient of the annular tooth on the pull rod, and transmit them to the control module 8; the control module 8 has storage and data processing functions, which are used to set the pull rod failure warning parameters, and perform logical judgment to control the alarm state of the alarm 9.

[0074] The brake nut 11 and the mold locking piston 4 are both provided with a plurality of teeth. The step S2 specifically comprises: obtaining the length of the stretched section of the tie rod through the structural state of the mold closing structure of the injection molding machine when the mold closing is completed, and the obtaining formula is:

[0075] L=L 1 +L 2 +H+L 3 +L 4 -L 5 -L 6 ;

[0076] like Figure 3 As shown, L 1L is the vertical distance from the first tooth position of the brake nut 11 close to the movable plate 12 to the movable plate 12 when the mold is closed; 2 is the thickness of the movable platen 12; H is the thickness of the mold 13 disposed between the movable platen 12 and the fixed platen 2; L 3 is the thickness of the fixed template 2; L 4 L is the vertical distance from the side of the fixed template 2 close to the rear cover to the inner wall of the rear cover; 5 L is the vertical distance from the first tooth position of the clamping piston 4 close to the cylinder barrel to the electronic ruler sensor block 6 when the mold is closed; 6 It is the vertical distance from the electronic ruler sensing block 6 or the pull rod away from one end of the movable template to the inner wall of the rear cover when the mold is closed; L is the length of the stretched section of the pull rod when the mold is closed.

[0077] The present invention establishes a relationship function between the normal elongation of the tie rod and the length of the stretched section of the tie rod and the clamping pressure difference, and uses the normal elongation of the tie rod obtained by the relationship function to set the tie rod failure warning parameter during the mold adjustment process, and obtains the real-time stretching length of the tie rod under the preset interval mold times during the operation of the injection molding machine. When the preset interval mold times count is equal to the preset number of times, the average value of the real-time stretching length of the tie rod under the preset interval mold times corresponding to the preset number of times is obtained, and the difference between the real-time stretching length of the tie rod and the average value is obtained under the current mold times of the injection molding machine as the tie rod elongation deviation value, and the tie rod elongation is judged. Whether the deviation value is greater than or equal to the target failure warning value, when the deviation values ​​of the draw rod elongation under the preset number of consecutive times are all greater than or equal to the target failure warning value, an alarm is issued. It continuously judges the deviation value of the draw rod elongation under each mode, and uses the judgment results of the preset number of consecutive modes as the basis for the alarm, which greatly improves the accuracy of the judgment and avoids misjudgment. It solves the problem in the prior art that most of the fatigue fractures of the draw rod occur suddenly and cannot be warned in advance. At the same time, it avoids the direct fracture of the draw rod, ensures the continuity of the machine operation, and improves the efficiency of product production.

[0078] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0079] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0080] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A tie rod failure warning method for an injection molding machine, characterized in that: include: S1: Establish the relationship function between the normal elongation of the tie rod and the length of the stretched section of the tie rod and the clamping pressure difference; The expression of the relationship function is: ; Where a is the tie rod diameter coefficient, is the flexibility coefficient of the mold structure, is the flexibility coefficient of the annular tooth on the tie rod, P is the clamping pressure difference, L is the length of the stretched section of the tie rod, is the normal elongation of the tie rod; the value of the flexibility coefficient of the mold clamping structure and the value of the flexibility coefficient of the annular tooth on the tie rod are obtained by finite element analysis method; S2: During the mold adjustment process, the length of the stretched section of the tie rod is obtained through the structural state of the mold clamping structure of the injection molding machine; the initial clamping pressure is set, and the clamping pressure difference between the initial clamping pressure and the corresponding clamping pressure at the end of the clamping is obtained, and the normal elongation of the tie rod is obtained by using the relationship function and the finite element analysis method through the length of the stretched section of the tie rod and the clamping pressure difference; The failure warning parameter of the tie rod is set according to the normal elongation of the tie rod to obtain the target failure warning value; S3: During the operation of the injection molding machine and at the preset interval mold times, the difference between the mold locking position distance corresponding to the tie rod when the mold locking force reaches the initial mold locking pressure and the mold locking position distance corresponding to the tie rod at the end of mold locking is obtained as the real-time stretching length of the tie rod, and the preset interval mold times count is increased by 1; S4: Determine whether the preset interval module count is equal to the preset number of times. If not, return to step S3. If so, obtain the average value of the real-time stretching length of the pull rod corresponding to the preset number of preset interval modules. S5: Under the current mode of the injection molding machine, the difference between the real-time stretching length of the tie rod and the average value is obtained as the tie rod elongation deviation value, and it is determined whether the tie rod elongation deviation value is greater than or equal to the target failure warning value. If so, the warning count is increased by 1; S6: In the next mold of the injection molding machine, determine whether the deviation value of the tie rod elongation is greater than or equal to the target failure warning value. If so, the warning count is increased by 1 and enters step S7; if not, the warning count is reset and returns to step S5; S7: Determine whether the warning count is equal to the preset number of times. If so, issue an alarm. If not, return to step S6. Step S7 also includes: S8: Replace the mold or the tie rod, and after the replacement, return to step S2 to reset the tie rod failure warning parameters; After resetting the pull rod failure warning parameters, it also includes adjusting them. The adjustment method is: Determine whether there is a mold in the preset mold interval in which the tie rod elongation deviation value is less than or equal to the set error value before replacing the mold or the tie rod. If so, use the reset tie rod failure warning parameter as the target failure warning value; if not, obtain the average value of the tie rod elongation deviation value in the preset mold interval, and adjust the reset tie rod failure warning parameter by the average value to obtain the target failure warning value; the end point of the preset mold interval is the final mold of the injection molding machine before replacing the mold or the tie rod, and the starting point of the interval is the mold separated by the preset number of times from the final mold; The specific method of resetting the pull rod failure warning parameters by adjusting the average value is as follows: Determine whether the average value satisfies the first determination condition, if so, adjust the tie rod failure warning parameter according to the first formula, if not, adjust the tie rod failure warning parameter according to the second formula; The first judgment condition is: , where is the average value, To set the error value, It is the target failure warning value in the previous mold adjustment process; The first formula is: , where is the pull rod failure warning parameter obtained after resetting, is the target failure warning value; The second formula is: .

2. A tie rod failure warning method for an injection molding machine according to claim 1, characterized in that: The mold clamping structure includes a pull rod, a fixed mold plate fixed on the pull rod, and a fixed mold plate movably arranged on the pull rod. A movable template on the pull rod, wherein the movable template can move along the pull rod toward a side away from or close to the fixed template; The mold closing structure also includes a brake nut and a locking cylinder. The brake nut is located on the side of the movable template away from the fixed template, and the brake nut can engage the pull rod. The locking cylinder includes a cylinder barrel and a rear cover. The cylinder barrel is fixed on the side of the fixed template away from the movable template, and the rear cover is arranged on the end of the cylinder barrel away from the fixed template. A locking piston is arranged in the cylinder barrel, and the locking piston is connected to the pull rod.

3. A tie rod failure warning method for an injection molding machine according to claim 2, characterized in that: A groove is arranged at one end of the pull rod close to the mold locking piston, and an electronic ruler sensing block is arranged in the groove; an electronic ruler is arranged on the back cover, which passes through the mold locking piston groove and is communicated with the electronic ruler sensing block, and is used to obtain the vertical distance from the electronic ruler sensing block to the inner wall of the back cover during the mold closing process.

4. A tie rod failure warning method for an injection molding machine according to claim 3, characterized in that: The brake nut and the locking piston are both provided with a plurality of teeth; the step S2 specifically comprises: obtaining the length of the stretched section of the tie rod through the structural state of the mold closing structure of the injection molding machine when the mold closing is completed, and the obtaining formula is: ； In the formula, It is the vertical distance from the first tooth position of the brake nut close to the moving platen to the moving platen when mold closing is completed; is the thickness of the moving template; is the thickness of the mold set between the movable mold plate and the fixed mold plate; is the thickness of the fixed template; It is the vertical distance from the side of the fixed template close to the rear cover to the inner wall of the rear cover; It is the vertical distance from the first tooth position of the clamping piston close to the cylinder barrel to the electronic ruler sensing block when the mold is closed; It is the vertical distance from the electronic ruler sensor block to the inner wall of the rear cover when the mold is closed; It is the length of the stretched section of the tie rod when mold closing is completed.

5. The method for early warning of tie rod failure for an injection molding machine according to claim 3, characterized in that: The clamping position distance is the vertical distance from the electronic ruler sensing block or the pull rod away from one end of the movable plate to the inner side wall of the rear cover.

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