Crushing chilling suppression method

Abstract

The present invention provides a method for suppressing crushing and quenching, which can easily suppress crushing and quenching from mixing into a molded product. A molding device includes a storage cylinder, a punch, a runner system unit, a molding die, a runner ring, a die casting unit, and a control device. The runner system unit includes a die-casting unit, a runner unit, and a gate unit. The control device drives the supply device in such a way that the molten metal flows in the storage cylinder, thereby sliding the punch. The control device sequentially calculates the continuously changing heat movement amount from the start of supplying the molten metal to the sliding of the punch to the position in FIG. 2 , and calculates the sum thereof as the total heat movement amount. Furthermore, the control device calculates the volume of the runner system unit based on various information related to the runner system unit input by the operator. The shapes of the storage cylinder and the runner system unit are determined in such a way that the crushing and quenching index becomes 0.842 or less.

Description

Technical Field

[0001] The invention relates to a crushing chilling suppression method. Background Art

[0002] It is widely known that a molded product is produced by injection molding by supplying a molten metal to a mold. For such a mold, a measure has been proposed to prevent crushed chill from being mixed into the molded product (see, for example, Patent Document 1).

[0003] Patent Document 1 proposes that, in order to improve the accuracy of fluid flow used to simulate the flow of fluid during the casting and forming processes in injection molding casting, the flow within the shot sleeve is incorporated into the model, or heat exchange between the die and heat transfer fluid (HTF) is incorporated into the model.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-506515 Summary of the Invention

[0007] [Problems to be solved by the invention]

[0008] Patent Document 1 uses Computer Aided Engineering (CAE), which requires a large number of parameters. Parameter determination and input take a considerable amount of time, and the calculation requires expensive equipment and personnel proficient in CAE, which is problematic.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for suppressing crushing chilling that can easily suppress the incorporation of crushing chilling into a molded product.

[0010] [Technical means to solve the problem]

[0011] The present invention provides a method for suppressing crushing chills during the injection step of an injection molding device, wherein the injection molding device comprises: a cylindrical cartridge; a punch slidable in the cartridge from one end to the other end along the axial direction; a runner system disposed at the other end of the cartridge for moving molten metal extruded from the cartridge by the punch; and a forming mold for injecting the molten metal moving through the runner system to form a product. The method comprises:

[0012] a contact area estimating step of estimating a contact area between the accumulator and the melt per unit time;

[0013] a total contact area estimating step of estimating a cumulative value of the contact area per unit time estimated in the contact area estimating step;

[0014] a crushing chilling index estimating step of estimating a crushing chilling index, wherein the crushing chilling index is a value obtained by dividing the total contact area estimated in the total contact area estimating step by the volume of the runner system portion; and

[0015] The shape determining step determines a shape of at least one of the accumulator and the runner system portion so that the crushing chill index becomes equal to or less than a predetermined value.

[0016] The applicant has conducted diligent research and found that the crushing chill index, which is a value obtained by dividing the total contact area by the volume of the runner system, is correlated with the mixing of crushing chill into the molded product. Specifically, it was found that if the crushing chill index becomes below a specified value, the mixing of crushing chill into the molded product is suppressed.

[0017] According to the method for suppressing crushing chill of the present invention, the shape of at least one of the accumulator and the runner system is determined so that the crushing chill index becomes equal to or less than a predetermined value, thereby easily suppressing the mixing of crushing chill into the molded product.

[0018] Furthermore, the total contact area estimated in the total contact area estimating step is preferably the total contact area obtained from the time the molten metal is poured into the cartridge until the moving speed of the punch that moves to squeeze the molten metal is switched to a high speed.

[0019] According to the above structure, the residence time of the molten metal in the storage cylinder can be shortened, and the molding time can also be shortened.

[0020] Furthermore, it is preferable that the runner system portion includes a die casting portion, a runner portion, and a gate portion, and the length of the runner portion is changed in the shape determining step.

[0021] According to the above configuration, the length of the flow channel portion is changed in the shape determination step, and thus the crushing chill index can be easily set to a predetermined value or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram showing a molding device according to an embodiment of the present invention.

[0023] Figure 2 A schematic diagram of a forming device showing a state in which a punch slides.

[0024] Figure 3 This is a schematic diagram showing the forming die, runner ring, and DB.

[0025] Figure 4 It is a graph showing various numerical values during casting of the first embodiment and the first to sixth comparative examples.

[0026] [Explanation of Symbols]

[0027] 10: Forming device

[0028] 11: Storage cylinder

[0029] 12: Punch

[0030] 13: Runner system department

[0031] 14: Forming die

[0032] 15: Sprue ring

[0033] 16: DB

[0034] 21: Die Casting Department

[0035] 22: Runner

[0036] 23: Gate DETAILED DESCRIPTION

[0037] Below, with reference to the attached Figure 1 Embodiments of the present invention will be described.

[0038] like Figures 1 to 3 As shown, the molding device 10 performs injection molding of, for example, aluminum melt M1 to form a molded product. In this embodiment, for example, a casing of a vehicle transmission is molded as the molded product.

[0039] The forming device 10 includes: a cylindrical cartridge 11; and a punch (tip) 12, which can be punched from the axial direction ( Figure 1 left and right directions) at one end ( Figure 1 right end) to the other end ( Figure 1 The punch 12 is moved along the Figure 1 The slide mechanism is driven (slid) under the control of the control device 20 that controls the molding device 10 . The melt M1 is supplied to the storage cylinder 11 by a supply device (not shown) that is driven under the control of the control device 20 .

[0040] Furthermore, the forming device 10 includes a runner system 13, which is disposed at the other end of the storage cylinder 11 ( Figure 1The left end of the mold 14 is provided with a molten metal M1 which is squeezed by the punch 12 in the storage cylinder 11 and is squeezed out from the storage cylinder 11; the forming die 14 is injected with the molten metal M1 which moves in the runner system 13 to form the molded product; the runner ring 15; and the distributor (hereinafter referred to as DB) 16.

[0041] The forming die 14 includes a fixed die 14a and a Figure 1 The movable mold 14b moves in the left and right directions, and the mold is locked by moving the movable mold 14b closer to the fixed mold 14a, and the mold is opened by moving the movable mold 14b away from the fixed mold 14a. Figure 1 The mold is locked by moving the movable mold 14b to the right. Figure 1 The movable mold 14b is moved in the left direction to open the mold. The movable mold 14b is moved by a mold moving mechanism (not shown), and the mold moving mechanism is driven by the control device 20.

[0042] The runner system 13 is formed by a die casting (stamp) portion 21, also called a sprue (biscuit) portion, a runner portion 22, and a gate portion 23 (see Figure 3 ). The die casting part 21 is formed by the runner ring 15. The runner part 22 is formed by the DB16 and the fixed mold 14a and the movable mold 14b. The gate part 23 is formed by the fixed mold 14a and the movable mold 14b. In addition, Figure 3 The two-dot chain line in is an imaginary line indicating the boundary between the respective parts 21 to 23 .

[0043] [Injection molding]

[0044] When forming a molded product using the forming device 10, the control device 20 is first controlled as follows. Figure 1 As shown, the mold moving mechanism is driven to move the movable mold 14b to Figure 1 Thus, a forming portion is formed as a cavity between the fixed mold 14a and the movable mold 14b.

[0045] Next, the control device 20 drives the supply device to supply the aluminum melt M1 into the accumulator 11. In this embodiment, the control device 20 drives the supply device so that the melt flows in the accumulator 11 at 0.1 m / sec, for example.

[0046] Next, if Figure 2 As shown, the control device 20 drives the slide mechanism to slide the punch 12 to the left. As the punch 12 slides to the left, the molten metal M1 in the accumulator 11 passes through the die casting portion 21, the runner portion 22, and the gate portion 23 of the runner system 13 and fills the forming portion of the forming die 14.

[0047] After the molten metal M1 filled in the forming portion of the forming mold 14 solidifies, the movable mold 14b is moved toward Figure 1 Next, the molded product is removed from the molding die 14. Thus, the molded product is formed.

[0048] In an apparatus that performs injection molding of a molten metal M1 to form a molded product, if crushed chills are mixed into the molded product, the molded product may become a defective product.

[0049] The present applicant has diligently studied and, as a result, discovered a method for suppressing the incorporation of crushed quenching into molded products.

[0050] In heat transfer, the amount of heat transfer is Q (J), the contact area is A (m 2 ), the temperature difference is set to ΔT (K), the heat flux is set to q (W / m 2 ), the heat transfer coefficient is set to h(W / m 2 K) and when time is Δt(t), the following equations (1) and (2) hold.

[0051] [Formula 1]

[0052] Q=q×A×Δt

[0053] [Formula 2]

[0054] q=h×ΔT

[0055] In the molding device 10 of this embodiment, the melt M1 is controlled to flow at 0.3 m / sec in the accumulator 11. When the flow rate of the melt M1 in the accumulator 11 is 0 to 0.1 m / sec, the heat transfer coefficient h (W / m 2 K) is constant, or even if it changes, the change is small. Therefore, the heat transfer coefficient h (W / m 2 K) can be approximated by an arbitrary constant.

[0056] In the forming apparatus 10 of this embodiment, the temperature difference between the left and right positions of the accumulator 11 during forming is small. In the forming apparatus 10, the initial fluid temperature (molten metal injection temperature) is controlled. The temperature of the accumulator 11 on the heat-receiving side (before the molten metal contacts it) reaches saturation and remains constant during continuous casting. The temperature distribution after the molten metal contacts the accumulator is influenced by the presence or absence of contact between the accumulator and the accumulator. In other words, the temperature difference ΔT can be expressed as a function of contact area between the accumulator and the accumulator.

[0057] Therefore, q in the above-mentioned formula (1) is a function of an arbitrary constant×the contact area, and the heat transfer amount Q in the cartridge 11 represented by the formula (1) can be approximated by the contact area per unit time.

[0058] Furthermore, during the casting process, the control device 20 sequentially calculates the time from the start of supplying the molten metal M1 to the time when the punch 12 slides to Figure 2 The control device 20 calculates the volume of the runner system portion 13 based on various information (dimensions) related to the runner system portion 13 input by the operator.

[0059] As a new index for suppressing the incorporation of crushing chill into molded products, the crushing chill index represented by formula (3) will be described.

[0060] [Formula 3]

[0061] Crushing chill index = total heat transfer / runner system volume

[0062] In the above (Formula 3), if the total heat transfer amount increases, the crushing chill index also increases, and if the runner system volume increases, the crushing chill index decreases.

[0063] In the molding device 10 , the shapes of the accumulator 11 and the runner system portion 13 are determined so that the crushing chill index becomes a predetermined value (for example, 0.842) or less.

[0064] like Figure 1 and Figure 3 As shown, in this embodiment, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3, and the stroke length of the punch 12 is X4.

[0065] [Example]

[0066] Using the forming device 10, such as Figure 4 The following experiments (Example 1, Comparative Examples 1 to 3) were conducted, in which casting was performed while changing the shapes of the die-cast portion 21 and the runner portion 22 of the runner system portion 13 and the stroke length of the punch 12 .

[0067] In the experiment, the control device 20 drives the supply device in such a way that the melt flows at 0.3 m / sec in the storage cylinder 11, so that the punch 12 moves from the storage cylinder 11 at a certain speed. Figure 1 Slide the position shown to Figure 2 Furthermore, the control device 20 sequentially calculates the time from the start of supplying the melt M1 to the time when the punch 12 slides to Figure 2 The control device 20 calculates the volume of the runner system portion 13 based on various information (dimensions) related to the runner system portion 13 input by the operator.

[0068] In Example 1 and Comparative Examples 1 to 3, it is determined whether the crushing chill index is below 0.842 (condition 1), whether the crushing chill has not reached the forming part of the forming mold 14 (condition 2), and whether the crushing chill has reached the forming part of the forming mold 14 under poor conditions (condition 3).

[0069] Furthermore, the so-called adverse conditions include, for example, a case where the temperature of the accumulator 11 falls below a predetermined temperature (e.g., 100° C.). These adverse conditions also include a case where the casting stoppage continues for a long period of time, causing the temperature of the accumulator 11 to cool (e.g., the period from the time casting is restarted after a shutdown in a factory where the forming apparatus 10 is installed, until the temperature of the accumulator 11 stabilizes after several injections are completed after mold preheating), or immediately after restarting the forming apparatus 10 after a short shutdown for maintenance, such as in winter, when the outside temperature is low.

[0070] [Example 1]

[0071] In Example 1, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3×2.667, the stroke length of the punch 12 is X4×0.907, the volume of the runner system portion 13 is X5×1.296, and the total heat movement is X6×0.936. The X1 to X6 are the values used in the following comparative example 1. In Example 1, the crushing chilling index is 0.788, which is determined to meet condition 1 that the crushing chilling index is less than 0.842, meet condition 2 that the crushing chilling does not reach the forming part of the forming mold 14, and meet condition 3 that the crushing chilling does not reach the forming part of the forming mold 14 under poor conditions. In addition, the length is Figure 1 The length in the left-right direction.

[0072] [Comparative Example 1]

[0073] In Comparative Example 1, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3, the stroke length of the punch 12 is X4, the volume of the runner system portion 13 is X5, and the total heat transfer is X6. In Comparative Example 1, the crushing chill index is 1.044, which indicates that the condition 1 of a crushing chill index of 0.842 or less is not met. The condition 2 of the crushing chill not reaching the forming portion of the forming die 14 (the crushing chill is mixed into the formed product) is not met. Furthermore, the condition 3 of the crushing chill not reaching the forming portion of the forming die 14 under unfavorable conditions (the crushing chill is mixed into the formed product) is not met.

[0074] [Comparative Example 2]

[0075] In Comparative Example 2, the thickness of the runner portion 22 is X1 × 1.667, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3, the stroke length of the punch 12 is X4, the volume of the runner system portion 13 is X5 × 1.230, and the total heat transfer is X6 × 1.025. In Comparative Example 2, the crushing chill index is 0.907, which indicates that the condition 1 of a crushing chill index of 0.842 or less is not met. The condition 2 of the crushing chill not reaching the forming portion of the forming die 14 is not met (the crushing chill is mixed into the formed product). Furthermore, the condition 3 of the crushing chill not reaching the forming portion of the forming die 14 under unfavorable conditions is not met (the crushing chill is mixed into the formed product).

[0076] [Comparative Example 3]

[0077] In Comparative Example 3, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2 × 1.65, the length of the runner portion 22 is X3, the stroke length of the punch 12 is X4, the volume of the runner system portion 13 is X5 × 1.267, and the total heat transfer is X6 × 1.025. In Comparative Example 3, the crushing chill index is 0.881, which indicates that the condition 1 of a crushing chill index of 0.842 or less is not met. The condition 2 of the crushing chill not reaching the forming portion of the forming die 14 is not met (the crushing chill is mixed into the formed product). Furthermore, the condition 3 of the crushing chill not reaching the forming portion of the forming die 14 under unfavorable conditions is not met (the crushing chill is mixed into the formed product).

[0078] [Comparative Example 4]

[0079] In Comparative Example 4, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3 × 2.300, the stroke length of the punch 12 is X4 × 0.899, the volume of the runner system portion 13 is X5 × 1.233, and the total heat transfer is X6 × 0.950. In Comparative Example 4, the crushing chill index is 0.842, which satisfies condition 1 of a crushing chill index of 0.842 or less, condition 2 of not reaching the forming portion of the forming die 14, and condition 3 of not reaching the forming portion of the forming die 14 under unfavorable conditions.

[0080] [Comparative Example 5]

[0081] In Comparative Example 5, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3 × 2.117, the stroke length of the punch 12 is X4 × 0.910, the volume of the runner system portion 13 is X5 × 1.196, and the total heat transfer is X6 × 0.956. In Comparative Example 5, the crushing chill index is 0.871, which indicates that the crushing chill index is 0.842 or less, condition 1 is not met. Condition 2 is met, indicating that the crushing chill does not reach the forming portion of the forming die 14. Condition 3 is also met, indicating that the crushing chill does not reach the forming portion of the forming die 14 under unfavorable conditions (the crushing chill is mixed into the formed product).

[0082] [Comparative Example 6]

[0083] In Comparative Example 6, the thickness of the runner portion 22 is X1, the length (thickness) of the die-cast portion 21 is X2, the length of the runner portion 22 is X3 × 2.450, the stroke length of the punch 12 is X4 × 0.891, the volume of the runner system portion 13 is X5 × 1.259, and the total heat transfer is X6 × 0.945. In Comparative Example 6, the crushing chill index is 0.82, which satisfies condition 1 of a crushing chill index of 0.842 or less, condition 2 of not reaching the forming portion of the forming die 14, and condition 3 of not reaching the forming portion of the forming die 14 under unfavorable conditions.

[0084] By determining the shapes of the accumulator 11 and the runner system 13 so that the crushing chill index is 0.842 or less, the crushing chill does not reach the forming portion of the forming die 14, thereby reducing the defective rate of the formed product.

[0085] Furthermore, when the length of the runner portion 22 is increased compared to Comparative Example 1 to reduce the crushing chill index (Example 1, Comparative Example 4, and Comparative Example 6), the crushing chill index can be significantly reduced compared to when the thickness of the runner portion 22 is increased compared to Comparative Example 1 to reduce the crushing chill index (Comparative Example 2), or when the length (thickness) of the die-cast portion 21 is increased compared to Comparative Example 1 to reduce the crushing chill index (Comparative Example 3). Therefore, when the shapes of the accumulator 11 and the runner system portion 13 are determined so that the crushing chill index is 0.842 or less, increasing the length of the runner portion 22 is preferred and effective in reducing the crushing chill index.

[0086] In addition, in addition to Example 1, Comparative Example 4, and Comparative Example 6, many experimental results were obtained that showed that the crushing chill did not reach the forming portion of the forming die 14 by setting the crushing chill index to 0.842 or less. Furthermore, in addition to Comparative Examples 1 to 3, many experimental results were obtained that showed that the crushing chill reached the forming portion of the forming die 14 when the crushing chill index was set to exceed 0.842. Regarding these experimental results, the same results were obtained in different forming devices that formed different formed products. Furthermore, in addition to Comparative Example 5, the following experimental results were obtained: when the crushing chill index was set to slightly exceed 0.842 (approximately 0.87), although condition 2 of the crushing chill not reaching the forming portion of the forming die 14 was met, under poor conditions, the crushing chill reached the forming portion of the forming die 14 (condition 3 was not met). Regarding these experimental results, the same results were obtained in different forming devices that formed different formed products.

[0087] From the above, it is clear that the prescribed value (0.842) is effective when determining the shapes of the accumulator 11 and the runner system 13 so that the crushing chill index is below a prescribed value (e.g., 0.842). Furthermore, the prescribed value can be varied depending on the structure and size of the molding apparatus 10. In this case, the prescribed value is also determined by conducting the same experiment as described above.

[0088] Preferred embodiments of the present invention have been described above, but those skilled in the art will readily understand that the present invention is not limited to these embodiments and can be modified appropriately without departing from the spirit of the present invention.

[0089] For example, in the above embodiment, the control device 20 sequentially calculates the time from the start of supplying the melt M1 to the time when the punch 12 slides to Figure 2 The heat movement amount that continuously changes to the position is calculated as the total heat movement amount, but the data of the total heat movement amount for various different conditions can be saved in advance as experimental result data in a memory (not shown). When the conditions are the same, the above calculation is not performed, and the data of the total heat movement amount for the same conditions are read from the memory and used as the total heat movement amount.

[0090] In the embodiment, the control device 20 calculates the volume of the runner system portion 13 based on the various information (dimensions) related to the runner system portion 13 input by the operator, but the volume data of the runner system portion 13 calculated in advance may be saved in the memory for each of the various information (dimensions) related to the runner system portion 13. In the case of the runner system portion 13 with the same information, the calculation is not performed, and the volume data of the runner system portion 13 with the same information is read from the memory and used as the volume of the runner system portion 13.

[0091] In the above embodiment, the cylindrical storage cartridge 11 is used, but any cylindrical shape is acceptable, and for example, a triangular cylindrical shape or a square cylindrical shape may be used.

[0092] In the above embodiment, the punch 12 is slid at a constant speed, but the speed can also be switched to a higher speed midway. In this case, the total contact area calculated is the total contact area from the time the melt M1 is injected into the accumulator 11 to the time the punch 12's moving speed is switched to a higher speed. This embodiment can shorten the residence time of the melt M1 within the accumulator 11, thereby shortening the forming time.

[0093] Furthermore, not all structural elements shown in the above embodiments are essential, and they may be appropriately selected or discarded without departing from the spirit of the present invention.

Claims

1. A method for suppressing crushing chill in an injection molding device, wherein the injection molding device comprises: Cylindrical storage cylinder; a punch capable of sliding axially from one end of the cartridge to the other end within the cartridge; a runner system portion disposed at the other end of the barrel for moving the molten metal extruded from the barrel by the punch within the barrel; and a forming die for injecting the molten metal moving through the runner system portion to form a product, wherein the crushing and chilling suppression method is characterized by comprising: a contact area estimating step of estimating a contact area between the accumulator and the melt per unit time; a total contact area estimating step of estimating a cumulative value of the contact area per unit time estimated in the contact area estimating step; a crushing chilling index estimating step of estimating a crushing chilling index, wherein the crushing chilling index is a value obtained by dividing the total contact area estimated in the total contact area estimating step by the volume of the runner system portion; and The shape determining step determines a shape of at least one of the accumulator and the runner system portion so that the crushing chill index becomes equal to or less than a predetermined value.

2. The crushing chilling suppression method according to claim 1, characterized in that: The total contact area estimated in the total contact area estimating step is the total contact area from the time the molten metal is poured into the cartridge until the moving speed of the punch that moves to squeeze the molten metal is switched to a high speed.

3. The crushing chilling suppression method according to claim 1 or 2, characterized in that: The runner system includes a die casting part, a runner part and a gate part. In the shape determining step, the length of the flow channel portion is changed.

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