Injection unit cylinder ramming protection method for injection molding machine

Abstract

The present application relates to injection molding machine technical field, and disclose a kind of injection molding machine injection unit cylinder collision material protection method, comprising the following steps: step one: first according to the system oil pressure value of hydraulic system pressure sensor feedback as one of judging conditions to judge the occurrence of cylinder collision material, calculate pressure change rate.The injection molding machine injection unit cylinder collision material protection method, actual pressure first-order derivative can be obtained pressure variation speed, pressure change rate is calculated by formula, then use position ruler to monitor the displacement of oil cylinder, the position reflected by oil cylinder is the position of injection screw, the speed of screw is obtained by first-order derivative of screw position, speed deviation rate is calculated by formula, by pressure change rate and speed deviation rate, obtain the condition of activating cylinder collision material protection: pressure change rate>2.5%&speed deviation rate>30%, to realize the protection of injection cylinder piston and cylinder cover, avoid collapse due to impact.

Description

Technical Field

[0001] This invention relates to the field of injection molding machine technology, specifically to a method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material. Background Technology

[0002] Injection molding machines, also known as injection molding machines or injection molding machines, are the main molding equipment used to produce various shapes of plastic products from thermoplastic or thermosetting plastics using plastic molds. They are classified as vertical, horizontal, and all-electric. Injection molding machines heat the plastic, apply high pressure to the molten plastic, and inject it to fill the mold cavity. The hydraulic control system of an injection molding machine is an important component, used for controlling injection, melting, mold opening and closing, and ejection. Depending on the plastic, the injection unit may need to adjust the temperature of the material cylinder in the area of ​​the temperature regulating ring, either by cooling or heating. Heat transfer occurs between the temperature regulating ring and the adjacent heating belt through the adjacent arrangement of the temperature regulating ring and the adjacent heating belt.

[0003] During the use of injection molding machines, some abnormal situations may occur due to unreasonable injection process settings or sudden mold failures, such as the following: 1. Due to incorrect holding pressure parameters, the injection cylinder fails to decelerate and stop before the mechanical zero position, causing the cylinder piston to hit the cylinder head at a high speed, resulting in cylinder collision. This phenomenon will damage the cylinder head and piston, affecting the service life of the cylinder. 2. During normal production, if the mold is already full or the injection nozzle is blocked, but the injection continues at high speed, the molten material in the barrel will create resistance to the movement of the injection screw, causing a sudden change in the deceleration of the injection screw, which will squeeze the injection screw and cause material collision. This phenomenon will cause cumulative damage to the injection screw and affect its service life. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for protecting the injection unit of an injection molding machine from cylinder collision and material impact. This method offers the advantage of protection and solves the problems of cylinder collision damaging the cylinder head and piston, affecting the service life of the cylinder, and material impact causing cumulative damage to the injection screw, thus affecting its service life.

[0006] (II) Technical Solution

[0007] To achieve the above-mentioned protection objectives, the present invention provides the following technical solution: a method for protecting the injection unit of an injection molding machine from cylinder collision and material impact, comprising the following steps:

[0008] Step 1: First, use the system oil pressure value fed back by the hydraulic system pressure sensor as one of the judgment conditions to determine whether cylinder collision or material collision has occurred. Calculate the pressure change rate, the formula of which is: Pressure change rate = Pressure change speed / Maximum equipment pressure ;

[0009] Step 2: Monitor the cylinder displacement using a position gauge. The cylinder position reflects the injection screw position. Calculate the speed deviation rate using the formula: Speed ​​Deviation Rate = (Set Speed ​​- Actual Speed) / Maximum Equipment Speed ;

[0010] Step 3: Based on the data model of pressure change rate and speed deviation rate, the conditions for activating cylinder collision and material impact protection are derived. The conditions for activating cylinder collision and material impact protection are: pressure change rate > 2.5% and speed deviation rate > 30%.

[0011] Step 4: When the above-mentioned protection conditions for cylinder collision and material impact are triggered, the screw needs to be braked in time;

[0012] Step 5: Compare the pressure reduction effect of different deceleration thresholds on the hydraulic system pressure during the injection unit's impact with the cylinder and material;

[0013] Step Six: By comparing the highest pressure, a threshold is selected to ensure the hydraulic system pressure.

[0014] Preferably, the system oil pressure value in step one is obtained by taking the first derivative of the actual pressure to get the rate of pressure change, and the pressure change rate is calculated by the formula. The normal operating pressure change rate is between 0.2% and 2%.

[0015] Preferably, the position of the injection screw in step two is specifically as follows: the screw speed can be obtained by taking the first derivative of the screw position, and the speed deviation rate can be calculated by the formula; the normal machine operating speed deviation rate is between -20% and 20%.

[0016] Preferably, the implementation method described in step four is to decelerate the oil pump motor to the fastest deceleration that the driver can withstand, until it decelerates to 0, and then exits the protection state.

[0017] Preferably, the fastest deceleration refers to the maximum deceleration that will not cause the driver to generate overcurrent or overvoltage alarms.

[0018] Preferably, the hydraulic system pressure described in step six will not exceed the set value.

[0019] Preferably, the injection molding machine control system includes a molding machine controller, a pressure sensor, a servo pump, a directional valve, a hydraulic cylinder, and a position gauge.

[0020] Preferably, the plastic machine controller is used to generate and output signals based on the detection signals received from the pressure sensor and the position gauge.

[0021] (III) Beneficial Effects

[0022] Compared with the prior art, the present invention provides a method for protecting the injection unit of an injection molding machine from cylinder collision and material impact, which has the following beneficial effects:

[0023] 1. This injection molding machine's injection unit cylinder collision and material impact protection method uses a position gauge. First, the system oil pressure value fed back by the hydraulic system pressure sensor is used as one of the judgment conditions. The first derivative of the actual pressure yields the pressure change rate. The pressure change rate is calculated using a formula. Then, the position gauge monitors the cylinder displacement, which reflects the injection screw position. The first derivative of the screw position yields the screw speed, and the speed deviation rate is calculated using a formula. Based on the pressure change rate and speed deviation rate, the conditions for activating the cylinder collision and material impact protection are: pressure change rate > 2.5% & speed deviation rate > 30%. This protects the injection cylinder piston and cylinder head, preventing breakage due to impact and ensuring safe production operation.

[0024] 2. This injection molding machine's injection unit cylinder collision and material impact protection method determines the protection conditions. When these conditions are triggered, the screw needs to be braked promptly. This is achieved by decelerating the oil pump motor to its maximum deceleration capacity, reducing it to zero, and then exiting the protection state. This protects the injection screw, preventing deformation and damage from high extrusion pressure and ensuring its service life. Based on experimental comparisons of different deceleration thresholds on the pressure reduction effect of the hydraulic system during cylinder collision and material impact, a reasonable threshold is selected by comparing the highest pressure to ensure that the hydraulic system pressure does not exceed the set value. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the injection unit of the injection molding machine of the present invention;

[0026] Figure 2 This is a block diagram of the injection action control for the injection molding machine according to the present invention;

[0027] Figure 3 This is a schematic diagram illustrating the effect after the invention is triggered. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figure 1-3 A method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, characterized by the following steps:

[0030] Step 1: First, use the system oil pressure value fed back by the hydraulic system pressure sensor as one of the judgment conditions to determine whether cylinder collision or material collision has occurred. Calculate the pressure change rate, the formula of which is: Pressure change rate = Pressure change speed / Maximum equipment pressure ;

[0031] Step 2: Monitor the cylinder displacement using a position gauge. The cylinder position reflects the injection screw position. Calculate the speed deviation rate using the formula: Speed ​​Deviation Rate = (Set Speed ​​- Actual Speed) / Maximum Equipment Speed ;

[0032] Step 3: Based on the data model of pressure change rate and speed deviation rate, the conditions for activating cylinder collision and material impact protection are derived. The conditions for activating cylinder collision and material impact protection are: pressure change rate > 2.5% and speed deviation rate > 30%.

[0033] Step 4: When the above-mentioned protection conditions for cylinder collision and material impact are triggered, the screw needs to be braked in time;

[0034] Step 5: Compare the pressure reduction effect of different deceleration thresholds on the hydraulic system pressure during the injection unit's impact with the cylinder and material;

[0035] Step Six: By comparing the highest pressure, a threshold is selected to ensure the hydraulic system pressure.

[0036] In the case implementation, the system oil pressure value in step one is: the rate of pressure change can be obtained by taking the first derivative of the actual pressure, and the pressure change rate can be calculated using the formula: Pressure Change Rate = Pressure Change Rate / Maximum Equipment Pressure The normal operating pressure change rate of the machine is between 0.2% and 2%. Step two, the injection screw position, specifically involves: taking the first derivative of the screw position to obtain the screw speed, and then calculating the speed deviation rate using the formula: Speed ​​Deviation Rate = (Set Speed ​​- Actual Speed ​​ / Maximum Equipment Speed) The normal operating speed deviation rate of the machine is between -20% and 20%. By measuring the pressure change rate and speed deviation rate, the conditions for activating the cylinder collision and material collision protection are obtained: pressure change rate > 2.5% & speed deviation rate > 30%. This protects the piston and cylinder head of the injection cylinder, prevents them from breaking due to impact, and ensures safe production operation.

[0037] In the case implementation, the conditions for cylinder collision and material impact protection were determined: pressure change rate > 2.5% & speed deviation rate > 30%. When these protection conditions are triggered, the screw needs to be braked in time. The implementation method is to decelerate the oil pump motor to the fastest deceleration that the driver can withstand until it reaches 0, and then exit the protection state. This protects the injection screw, avoids deformation and damage to the screw due to high extrusion pressure, and ensures the screw's service life. Based on experimental comparison of different deceleration thresholds on the pressure reduction effect of the hydraulic system when the injection unit experiences cylinder collision and material impact, a reasonable threshold is selected by comparing the highest pressure to ensure that the hydraulic system pressure does not exceed the set value.

[0038] When implementing this procedure, please follow these steps:

[0039] 1) First, determine if cylinder collision or material impact has occurred: Use the system oil pressure value fed back by the hydraulic system pressure sensor as one of the judgment conditions. Then, take the first derivative of the actual pressure to obtain the rate of pressure change, and calculate the pressure change rate DATE01 using the formula: DATE01 = Rate of pressure change / Maximum equipment pressure On a normal machine, DATE01 usage is between 0.2% and 2%.

[0040] 2) Then monitor the cylinder displacement using a position gauge. The cylinder position reflects the injection screw position. The screw speed can then be obtained by taking the first derivative of the screw position. The speed deviation rate DATE02 can then be calculated using the formula: DATE02 = (Set speed - Actual speed) / Maximum equipment speed. On a normal machine, DATE02 runs between -20% and 20%.

[0041] 3) Based on the above two data models, a large amount of experimental data was tested and verified, and the following conditions for activating the cylinder collision and material collision protection were obtained: DATE01>2.5% & DATE02>30%;

[0042] 4) Finally, the hydraulic system is used for pressure relief and braking. When the above-mentioned protection conditions for cylinder collision and material impact are triggered, the screw needs to be braked in time. The implementation method is to decelerate the oil pump motor to the fastest deceleration that the driver can withstand, until it reaches 0, and then exit the protection state.

[0043] In summary, this injection molding machine's injection unit cylinder collision and material impact protection method, by setting a position gauge, first uses the system oil pressure value fed back by the hydraulic system pressure sensor as one of the judgment conditions. The first derivative of the actual pressure yields the pressure change rate, and the pressure change rate is calculated using a formula. Then, the position gauge monitors the cylinder displacement, and the cylinder position reflects the injection screw position. The first derivative of the screw position yields the screw speed, and the speed deviation rate is calculated using a formula. Based on the pressure change rate and speed deviation rate, the conditions for activating the cylinder collision and material impact protection are obtained: pressure change rate > 2.5% & speed deviation rate > 30%. This protects the injection cylinder piston and cylinder head, preventing breakage due to impact and ensuring safe production operation.

[0044] Furthermore, by deriving the conditions for cylinder collision and material impact protection, when the aforementioned protection conditions are triggered, the screw needs to be braked in time. The implementation method is to decelerate the oil pump motor to the fastest deceleration that the driver can withstand, until it decelerates to 0, and then exits the protection state, thereby protecting the injection screw, avoiding high extrusion pressure that could deform and damage the screw, and ensuring the screw's service life. Based on experimental comparisons of different deceleration thresholds on the pressure reduction effect of the hydraulic system when the injection unit experiences cylinder collision and material impact, a reasonable threshold is selected by comparing the highest pressure to ensure that the hydraulic system pressure does not exceed the set value.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for protecting the injection unit of an injection molding machine from cylinder collision and material impact, characterized in that: Includes the following steps: Step 1: First, use the system oil pressure value fed back by the hydraulic system pressure sensor as one of the judgment conditions to determine whether cylinder collision or material collision has occurred. Calculate the pressure change rate, the formula of which is: Pressure change rate = Pressure change rate / Maximum equipment pressure / 1000 * 100%; Step 2: Monitor the displacement of the hydraulic cylinder using a position gauge. The position of the hydraulic cylinder reflects the position of the injection screw. Calculate the speed deviation rate using the formula: Speed ​​Deviation Rate = (Set Speed ​​- Actual Speed) / Maximum Equipment Speed ​​* 100%; Step 3: Based on the data model of pressure change rate and speed deviation rate, the conditions for activating cylinder collision and material impact protection are derived. The conditions for activating cylinder collision and material impact protection are: pressure change rate > 2.5% and speed deviation rate > 30%. Step 4: When the above-mentioned protection conditions for cylinder collision and material impact are triggered, the screw needs to be braked in time; Step 5: Compare the pressure reduction effect of different deceleration thresholds on the hydraulic system pressure during the injection unit's impact with the cylinder and material; Step Six: By comparing the highest pressure, a threshold is selected to ensure the hydraulic system pressure.

2. The method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, as described in claim 1, is characterized in that: The system oil pressure value mentioned in step one is obtained by taking the first derivative of the actual pressure to get the rate of pressure change, and the pressure change rate is calculated by the formula. The normal operating pressure change rate is between 0.2% and 2%.

3. The method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, as described in claim 1, is characterized in that: The specific position of the injection screw in step two is as follows: the screw speed can be obtained by taking the first derivative of the screw position, and the speed deviation rate can be calculated by the formula; the normal machine operating speed deviation rate is between -20% and 20%.

4. The method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, as described in claim 1, is characterized in that: Step four involves slowing the oil pump motor down to 0 using the fastest deceleration the driver can withstand, and then exiting the protection state.

5. A method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, as described in claim 4, characterized in that: The fastest deceleration refers to the maximum deceleration that will not cause the driver to generate overcurrent or overvoltage alarms.

6. A method for protecting the injection unit of an injection molding machine from cylinder collision and material impact as described in claim 1, characterized in that: The hydraulic system pressure described in step six will not exceed the set value.

7. A method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, as described in claim 1, comprising an injection molding machine control system, characterized in that: The injection molding machine control system includes a machine controller, pressure sensor, servo pump, directional valve, hydraulic cylinder, and position gauge.

8. A method for protecting the injection unit of an injection molding machine from collisions with the cylinder and material, as described in claim 7, characterized in that: The plastic machine controller is used to generate and output signals based on the detection signals received from the pressure sensor and the position gauge.

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