JP2020157366A - Life prediction method of injector for die cast machine - Google Patents

Abstract

To provide a life-prediction method of an injector for a die cast machine that allows for accurately predicting the life (remaining number of shots) of a component making up an injector for a die cast machine.SOLUTION: A life-prediction method of an injector for a die cast machine has, provided that an average value of casting pressure applied to each divisional section of a division into N equal parts of an evaluation section set within a moving range of an injection plunger is taken as a Pm value (m=1, 2, ...N), a value obtained by dividing an integration value, Psum value, of the Pm values in the evaluation sections X-Y by a length Y-X of the evaluation section is taken as a Pav value, a maximum value of casting pressure Pm values in the evaluation sections X-Y is taken as Pmax value, and an occurrence stroke value thereof is taken as a St value, a step in which reference values with respect to disparities from a predetermined numerical value are respectively provided for the Pav value and the Pmax value, the Pav value and the Pmax value are compared with respective disparities, and points for gall degrees are given respectively to the Pav value and the Pmax value, and a step for determining a component exchange when a value obtained by integrating the points for each number of shots of the injection plunger reaches a life integration value that becomes a predetermined component life.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for predicting the life of a component, for example, a plunger mechanism, which constitutes an injection device of a die casting machine.

FIG. 7 is an explanatory view of an injection device of a die casting machine. In a general die casting machine, a product is formed by filling a cavity 8 of a mold 1 composed of a fixed mold 2 and a movable mold 3 with a high-temperature molten metal at a high pressure using an injection device. When molding this product, first, the injection sleeve 4 is filled with molten metal by a water heater, and the plunger tip 5 slidably provided in the injection sleeve 4 is placed at low speed or high speed by the injection cylinder 7 via the injection plunger 6. The molten metal is injected into the cavity 8 by advancing with.
In general, when an injection device is repeatedly operated for a long period of time, for example, injection of molten metal is repeated, the plunger tip 5 is worn, and solidified metal particles adhere to the injection sleeve 4, so that a stable predetermined injection is performed. The speed cannot be achieved, and so-called galling occurs, such as the injection speed changing in a wavy manner.

Such galling causes abnormal noise and sliding resistance. Of these, the sliding resistance accelerates the wear of the plunger tip 5 and the injection sleeve 4, and shortens the life of the cast part. Then, the cost of consumables and the replacement time increase, and as a result, the manufacturing cost increases.
Further, as the wear progresses, burrs (burrs) are generated in the gap between the plunger tip 5 and the injection sleeve 4 in the vicinity of the filling completion position, the protrusion and the injection retreat cannot be performed, and the short-time stop is repeatedly generated. In extreme cases, backflushing may occur, leading to a fire or the like.
Further, when the gap between the plunger tip 5 and the injection sleeve 4 increases, aluminum is inserted, a desired injection speed cannot be obtained, and a product defect occurs.
In addition, the temperature of the molten metal may drop and air may be entrained in the molten metal. Then, there is a risk of causing defects such as deterioration of the hot water circulation in the cavity 8 and generation of nests in the product, and shortening the life of the plunger tip 5 and the injection sleeve 4.

In general, parts constituting the injection device of a die casting machine, for example, cast parts used for a plunger mechanism, deteriorate over time due to thermal deformation, aluminum sticking, lubricant adhesion, and the like. Each part has a difference in the rate of progress of wear depending on the degree of galling. FIG. 8 is a graph showing the relationship between the number of conventional shots and the degree of galling, and the vertical axis shows the degree of galling (points) and the horizontal axis shows the number of shots. As shown in FIG. 1 (1), the worse the degree of galling, the more production-inhibiting factors such as backflushing occur with a small number of shots as in chip A, and early replacement is required. If the degree of galling of the replaced chip B is not as bad as that of A, the number of shots is also larger than that of A.
When a production obstruction factor such as backflush occurs, the operation is stopped and the chip is replaced, resulting in a large production loss. Therefore, as shown in Fig. (2), the replacement timing (shot quantity, etc.) determined in advance based on past experience. ) Is reached, the chip A is replaced with the chip B, and the chip B is replaced with the chip C. In this case, since the parts are replaced at a uniform timing regardless of the current degree of galling, parts that can actually be used sufficiently (see the use loss of B in the figure) may be discarded.

Therefore, it is safe to detect the galling of the plunger tip mechanism that causes such a defect at an early stage and maintain the plunger tip 5 and the injection sleeve 4 to maintain high quality of the product and prevent damage to the die casting machine. It is important for maintenance, and various galling detection methods have been conventionally proposed (for example, disclosed in Patent Document 1).
The galling degree detecting method disclosed in Patent Document 1 detects the value of the casting pressure applied to the plunger tip 5 in detail for each shot, and detects the galling size and the position from the value of the casting pressure. However, although it is possible to recognize the current degree of galling of the components, information on the subsequent life cannot be obtained, and the replacement timing is determined from the latest one-shot data, so there is a risk that the production plan may change suddenly. , There was a risk that the arrangement of replacement parts would be delayed and the operation would stop.

Japanese Unexamined Patent Publication No. 2017-104871

An object to be solved by the present invention is to provide a predictive method capable of accurately predicting the life (number of remaining shots) of a component constituting an injection device of a die casting machine in view of the above-mentioned problems of the prior art.

In the present invention, as a first means for solving the above problems, an evaluation section is set within the moving range of the injection plunger and divided into N, and the average value of the casting pressure applied to each divided section is a Pm value (m). = 1, 2, ... N), and the value obtained by dividing the integrated value Psum value of the Pm values of the evaluation sections X to Y by the length YX of the evaluation section is used as the Pav value, and the casting of the evaluation sections X to Y is performed. When the maximum value of the pressure Pm value is the Pmax value and the generated stroke value is the St value, a reference value for the distance between the Pav value and the Pmax value is set for each of the Pav value and the Pav value. A step of comparing the Pmax value with each distance and scoring the degree of galling for each of the Pav value and the Pmax value.
A die casting machine characterized by having a step of determining that a part is to be replaced when the value obtained by accumulating the points for each shot number of the injection plunger reaches a life integrated value which is a predetermined part life. The purpose is to provide a method for predicting the life of an injection device.
According to the first means, it is possible to predict the replacement time of the component parts with high accuracy.

According to the present invention, as a second means for solving the above problems, in the first means, the number of remaining shots L from the replacement of parts to the life of the parts is M for the life of the parts and shots for which the parts have been cast. An object of the present invention is to provide a method for predicting the life of an injection device of a die casting machine, which is obtained from L = M / (A / N) -N, where N is a number and A is a cumulative score.
According to the second means, it is possible to obtain the predicted number of shots until the part life is reached based on the actual value of casting a certain number of shots after the parts are replaced.

The present invention is characterized in that, as a third means for solving the above-mentioned problems, in the first or second means, the score of the degree of galling is an arbitrary value added according to the degree of galling. The purpose is to provide a method for predicting the life of an injection device of a machine.
According to the third means, the accuracy of life prediction can be improved.

In the present invention, as a fourth means for solving the above-mentioned problems, in any one of the first to third means, when the value obtained by accumulating the points reaches the life integrated value, a component replacement alarm is given. It is an object of the present invention to provide a method for predicting the life of an injection device of a die casting machine, which is characterized by generating.
According to the fourth means, it is possible to reduce the loss of operating time by arranging replacement parts in advance before the parts need to be replaced.

According to the present invention, it is possible to predict the life of a component component with high accuracy, such as the number of remaining shots.

It is a graph which shows the relationship between an injection stroke, an injection speed, and a casting pressure. It is explanatory drawing of the evaluation section XY. It is a processing flow diagram of the life prediction method of the injection device of the die casting machine of this invention. It is a detailed flow chart of the process A of FIG. It is explanatory drawing of the evaluation score. It is explanatory drawing which shows the relationship between the number of shots of this invention and the degree of galling. It is explanatory drawing of the injection device of a die casting machine. It is a graph which shows the relationship between the number of conventional shots and the degree of galling.

An embodiment of a method for predicting the life of the injection device of the die casting machine of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a graph showing the relationship between the injection stroke, the injection speed, and the casting pressure. FIG. 2 is an explanatory diagram of the evaluation section XY. FIG. 3 is a processing flow chart of a method for predicting the life of the injection device of the die casting machine of the present invention. FIG. 4 is a detailed flow chart of the process A of FIG. FIG. 5 is an explanatory diagram of evaluation points. FIG. 6 is an explanatory diagram showing the relationship between the number of shots of the present invention and the degree of galling.
In general die casting machine casting work, one product is molded in the process of mold clamping, pouring, injection start, cooling (solidification), mold opening, product removal, product detection, mold spraying, injection retreat, and chip lubrication. This shot is repeated as one shot (also referred to as one cycle) (see FIG. 3). The present invention detects in detail the value of the casting pressure applied to the plunger tip 5 at the start of injection (specifically, after collecting the injection waveform (S1 in FIG. 3), time, injection stroke, injection speed, head pressure, Collected data such as rod pressure and casting pressure are obtained (S2 in FIG. 3), and the galling size and position are detected from the value of casting pressure (S3 in FIG. 3).

FIG. 1 shows the injection waveforms of the injection speed and the casting pressure when the injection plunger 6 is used for injection. The stroke of the plunger tip 5 is taken on the horizontal axis, and the injection speed (m / s) and the casting pressure (MPa) are shown on the vertical axis. The injection speed is divided into a low speed section and a high speed section. In this figure, the stroke is low up to 535 mm and high speed when the stroke is 535 mm or more. In the present embodiment, the evaluation section is set to 20 mm to 535 mm as an example. The width of the evaluation section divided into N equal parts was set to 1 mm. The average value of the casting pressure applied to each division section was taken as the Pm value (m = 1, 2, ... N). On the other hand, the plunger tip 5 is advancing while the value of the casting pressure fluctuates. In this figure, the Pm value shows the waveform of the casting pressure, and the Pmax value shows the maximum value of the Pm value in the evaluation section.

Next, the evaluation section (XY) is set within the moving range of the plunger tip 5 (see FIG. 2). The casting pressure when the plunger tip 5 moves is divided into N equal parts in the evaluation section. If the step width divided into N equal parts is, for example, 1 mm, the casting pressure is measured at intervals of 1 mm in width. The average casting pressure value for each injection stroke of 1 mm is calculated in the PC of the die casting machine and used as the Pm value (MPa).
Here, the evaluation section and the value of the casting pressure will be described in a simulated manner. When the evaluation section is changed from X to Y and the step of the casting pressure is 1 mm as an example, the value of Pm is the average value of the values of the width of 1 mm.
Based on the definition of the pressure Pm, FIG. 2 is a rewrite of the waveforms of the casting pressure and the injection speed.
Set the injection stroke range of the low speed section where you want to evaluate and manage galling. The evaluation sections X to Y (mm) (Y> X) are 20 to 535 mm in FIG.
The high-speed section can also be evaluated, but the casting pressure value in the high-speed section changes depending on the gate resistance and the injection speed set value.

As described above, the Pm value (MPa) is the average pressure value of the evaluation sections X to Y in 1 mm increments (S4 in FIG. 3).
The Pm values (MPa) of the evaluation sections X to Y (mm) (S5 in FIG. 4) are integrated to obtain the Psum value (MPa). The evaluation section distance is divided by YX (mm) and generalized to Psum / (YX) = Pav value (MPa / mm) (S6 in FIG. 4). This makes it possible to generalize the casting pressure and the area of the injection stroke. As a result, even if the casting pressure is low, it is determined that the degree of galling is poor if the width is wide.
The maximum value of the casting pressure or Pm value in the evaluation sections X to Y (mm) and the generated stroke value thereof are extracted. Pmax value (MPa) and St value (mm) (S7 in FIG. 4). This is evaluated by paying attention to the magnitude of the peak of the casting pressure. That is, even if the width is narrow, a high casting pressure peak is judged to be bad.
The Pav value (MPa / mm) is provided with a gap Aa, the evaluation is performed a times, and a score is given. The distance Aa may be changeable or may be a fixed value (S8 in FIG. 4).

For example, if the distance is A1, A2, ... Aa, 1 point is added if Pav value ≥ A1, 1 point is added if Pav value ≥ A2 ... If Pav value ≥ Aa, 1 point is added so that the maximum a point is obtained. (S9 in FIG. 4).
The Pmax value (MPa) is provided with b gaps Bb, and the evaluation is performed b times. Score like the Pav value. The gap Bb may be changed and fixed (S10 in FIG. 4).
For example, in the case of distances B1, B2, ... Bb, 1 point is added if Pmax value ≥ B1, 1 point is added if Pmax value ≥ B2 ... 1 point is added if Pmax value ≥ Bb so that the maximum is b points. (S11 in FIG. 4).
The degree of galling is scored, that is, the total of the scores for the a and b grades (S9 and S11 in FIG. 4) is calculated (S12 in FIG. 3).

FIG. 5 shows the score of the degree of galling obtained by comparing each value of the Psum value, Pav value, Pmax value, and St value obtained in the actual casting (number of shots (No) 35 times) with the distance. In this data, the gap is an example in which both the Pav value and the Pmax value are compared with five. From this, as can be seen, the scores of the Pav value (a evaluation) and the Pmax (b evaluation) value are both evaluated with a score from 0 to 5. In addition, the score (n evaluation) of the degree of galling, which is the sum of the Pav value and the Pmax value, and the St value are displayed for each shot. According to this, it is shown that the possibility of galling is the highest when the score of the degree of galling (n evaluation) is 10 points. In this table, it can be determined that the place where the number of points is 10 is large, that is, the stroke St value is from 450 mm to 535 mm and the degree of galling is large.
The points (total) of the degree of galling are integrated, and the remaining life (number of remaining shots) is predicted and calculated after the lapse of a predetermined operating time (S13 in FIG. 3). FIG. 6 is an explanatory diagram showing the relationship between the number of shots of the present invention and the degree of galling. As shown in FIG. 2 (2), when the points for each shot are integrated, they appear in a substantially straight line rising to the right like the chip A integrated value a.

When the number of gnawing points (average value) for each shot is plotted in the time series of the number of shots, the average value of the gnawing degree points and the tendency of the gnawing degree points for each shot, for example, the gnawing degree is for each shot. It is possible to visually recognize whether the number is increasing or decreasing, whether the shot has a large score in general, or whether the shot has a locally large score.
Further, depending on the degree of galling (the degree of wear, etc.), an arbitrary value may be added when the total score is large. This makes it possible to predict the life with high accuracy.
If there is an actual value of parts replacement, the number of remaining shots L until the part life is reached is L = M / (A /) when the part life is M, the number of cast shots is N, and the cumulative number is A. N) It can be obtained from -N. The larger the number of shots N cast, the higher the accuracy of life prediction.

The integrated value of the degree of galling obtained in S13 and the predicted value of the remaining life (number of remaining shots) are stored (S14 in FIG. 3).
The cumulative value of the degree of galling and the predicted value of the remaining life are displayed (S15 in FIG. 3).
An integrated value of the degree of galling points is set (integrated life value) (S16 in FIG. 3). The life integrated value c, which is the component life, is determined in advance. The life integrated value c of the present embodiment is, for example, an integrated value in a state where it can be determined with reference to the actual usage value of the parts replaced in the past, the parts need not be replaced immediately, and several shots can still be performed. ..
When the integrated value reaches the life integrated value, an alarm is issued or a warning is issued (S17 in FIG. 3). As a result, it is possible to reduce the loss of operating time, such as arranging replacement parts in advance before parts need to be replaced.
After the warning, if necessary, the next cycle is not performed (No), casting is completed, and parts are replaced. On the other hand, the next cycle is performed (Yes) until the integrated value reaches the life integrated value.
According to the method of predicting the life of the injection device of the die casting machine of the present invention, as shown in FIG. 6 (1), the chip B is arranged and the parts are replaced before the product life of the chip A (replacement of parts required) is reached. Can be performed, and the usage loss of the chip A can be significantly reduced. In addition, the life of parts constituting the injection device of the die casting machine, such as the plunger mechanism, the injection sleeve, and the number of remaining shots of the plunger tip, can be predicted with high accuracy.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.
Further, the present invention is not limited to the combinations shown in the embodiments, and can be implemented by various combinations.

The method for predicting the life of a die casting machine injection device of the present invention has industrial applicability, especially in a die casting machine injection device.

1 Mold 2 Fixed mold 3 Movable mold 4 Injection sleeve 5 Plunger tip 6 Injection plunger 8 Cavity

Claims (4)

An evaluation section is set within the movement range of the injection plunger and divided into N, and the average value of the casting pressure applied to each divided section is set to the Pm value (m = 1, 2, ... N), and the evaluation sections XY The value obtained by dividing the integrated value Pm value of the Pm value by the length YX of the evaluation section is defined as the Pav value, the maximum value of the casting pressure Pm value in the evaluation sections X to Y is defined as the Pmax value, and the generated stroke value is St. When used as a value, a reference value for a distance between the Pav value and the Pmax value is set for each of the predetermined values, the Pav value and the Pmax value are compared with the respective distances, and the Pav value and the Pmax value are compared with each other. The process of scoring the degree of galling for each value and
A die casting machine characterized by having a step of determining that a part is to be replaced when the value obtained by accumulating the points for each shot number of the injection plunger reaches a life integrated value which is a predetermined part life. How to predict the life of the injection device. In the method for predicting the life of the injection device of the die casting machine according to claim 1.
The number of remaining shots L until the part life is reached after the part is replaced is L = M / (A / N) -N when the part life is M, the number of shots cast is N, and the cumulative number is A. A method for predicting the life of an injection device of a die casting machine, which is characterized by obtaining from. In the method for predicting the life of the injection device of the die casting machine according to claim 1 or 2.
A method for predicting the life of an injection device of a die casting machine, characterized in that an arbitrary value is added to the score of the degree of galling according to the degree of galling. In the method for predicting the life of an injection device of a die casting machine according to any one of claims 1 to 3.
A method for predicting the life of an injection device of a die casting machine, characterized in that an alarm for parts replacement is generated when the integrated value of the points reaches the integrated life value.