JPH0788864A - Powder slush molding method - Google Patents

Abstract

PURPOSE:To obtain proper mold temp. by measuring the temp. of a mold temp. change factor at every process and substituting the measured value for a relational expression of the temp. of the factor preliminarily calculated by multiple regression analysis and the quantity and supply time of a supply heat source and changing the quantity and time of the supply heat source on the basis of the calculated value. CONSTITUTION:In a heating furnace 2, hot air is sprayed on the single surface of a mold 1 from the inner wall of the furnace in a preheating process 1 and sprayed on the upper and rear surfaces of the mold in a process 2'' and sprayed on the single surface of the mold 1 in a process 3' to heat the mold 1 to proper temp. Therefore, the hot air is adjusted by a heating medium supply device Q and a supply time control valve X. In a molding process II, a powder material is bonded to the mold l and, in a curing process III, hot air is sprayed on the mold to control the temp. of the mold so as to hold the same to temp. suitable for curing to perform curing. The temp. of the factor related to the change of mold temp. calculated by multiple regression analysis is substituted for the relational expression of the temp. of the factor, the quantity of a heating medium and the supply time of the heating medium and, on the basis of the calculated value, the quantity Q and time X of the heating medium are adjusted to obtain proper mold temp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instrument panel of an automobile, a headrest, an armrest, or
The present invention relates to a powder slush molding method, which is a molding method of a resin molded product used as a cover or cover of a console box, other cushions and toys, and particularly to a method of adjusting the mold temperature thereof.

[0002]

2. Description of the Related Art A powder slush molding method will be described with reference to the graph of FIG. In FIG. 3, the abscissa axis represents the respective molding steps sequentially performed with the passage of time, and the ordinate axis represents the mold temperature in each of the steps. The powder slush molding method includes a preheating step of heating the slush molding die, a molding step of supplying resin powder to the mold surface, and a curing step of heating and melting the resin powder to crosslink the resin powder to a stable state. A cooling step of cooling and solidifying the resin
A product is molded by sequentially repeating the demolding step of removing the solidified resin from the mold as one cycle.

At this time, in order to stably mass-produce high-quality molded products, it is important to set the mold temperature of the mold to a constant and appropriate temperature for each process. In particular, in the preheating step, preheating is performed until the temperature becomes a temperature suitable for molding, which is the next step, and in the curing step, the temperature β that is suitable for curing is maintained. You have to lower it to. Therefore, in the conventional powder slush molding method, the amount of the heat medium to be supplied in each step or the supply time of the heat medium or the refrigerant is uniformly determined for each mold.

However, even if the amount of the heat medium or the supply time of the heat medium or the refrigerant is uniformly set, the mold temperature rising / falling curve is
As shown by the solid line in FIG. 3, the temperature range in which it changes in summer and winter is different, and there are considerable widths α ′, β ′, γ ′ in the temperatures after preheating, immediately before curing, and immediately before demolding. This temperature range is caused not only by the season but also by changes in the conditions within one day. Furthermore, in the mold temperature before the preheating step, there is a considerable difference between the mold temperature when the molding is temporarily stopped and restarted immediately after the mold change, after a holiday, after a break, and the mold temperature during which the molding cycle is repeated. come. Therefore, as in the conventional powder slush molding method, a method of uniformly setting the amount of heat medium to be supplied in each step or the supply time of heat medium or refrigerant for each mold is used for stable mass production of high-quality molded products. In addition, it is difficult to keep the mold temperature of the mold constant and appropriate for each process.

Therefore, the conventional mold temperature adjusting method adopted is to measure the increased mold temperature after the preheating process and before the molding, and move to the molding process only when the allowable temperature range suitable for the molding is obtained. If the temperature exceeds the allowable temperature range, the mold temperature is left to fall within the allowable temperature range.If the temperature exceeds the allowable temperature range, all the steps after preheating, that is, the molding step, A method of idle operation including a curing step, a cooling step, a demolding step was adopted.

[0006]

However, in such a conventional mold temperature adjusting method, when the specification of the molding quality becomes strict and the width of the allowable temperature range is narrowed, the mold temperature falls within the allowable temperature range after preheating. There is a problem that the number of times molds are left unattended or run idle until the mold temperature falls within the allowable temperature range, which reduces the operating rate and increases energy loss, etc. Was there.

The present invention has been made in view of the above problems, and it is an object of the present invention to make it easy to set the mold temperature of the molding die to a constant and appropriate temperature for each process, and Provided is a powder slush molding method capable of stably mass-producing molded products.

[0008]

In order to achieve the above object, the powder slush molding method of the present invention includes a preheating step, a curing step, and a cooling step to produce a product while supplying a heat medium or a refrigerant in each step. In the powder slush molding method for molding, in order to obtain an appropriate mold temperature in each process, the temperature of a factor related to the rise and fall of the mold temperature is measured in each process, and the measured value is obtained in advance by multiple regression analysis. Substituting in the relational expression between the temperature of the factors related to the rise and fall of the mold temperature and the amount of heat medium supplied in each process, or the supply time of the heat medium or the refrigerant, the value calculated in each process by this relational expression Based on the amount of heat medium to be supplied in each step, or a method of molding by varying the supply time of the heat medium or the refrigerant, the relational expression, in the preheating step, curing step, the amount of heat medium or its supply time. Mold temperature and ambient temperature A quadratic function, and a heating medium temperature to be supplied, a furnace inner wall temperature, and a linear function of the material temperature. In the cooling step, the supply time of the refrigerant is expressed as a linear function of the ambient temperature and the refrigerant temperature. Is.

[0009]

According to the above means, the multiple regression analysis quantitatively correlates the temperature of the factors related to the rise and fall of the mold temperature in each step with the amount of the heat medium to be supplied or the supply time of the heat medium or the refrigerant. Since it is attached, it is possible to calculate the amount of heat medium required to obtain an appropriate mold temperature in each step from the temperature factor, or the supply time of the heat medium or the refrigerant, and to the calculated value. Based on the amount of heat medium supplied in each process,
Alternatively, if the supply time of the heat medium or the refrigerant is changed, it becomes easy to maintain a constant and appropriate mold temperature for each process.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an example of the equipment form of the powder slush molding method of the present invention. The equipment shown in FIG. 1 has a plurality of molding dies online, I preheating, II molding, III cure, I
A method of performing molding by repeating V cooling, V demolding, and sequential conveyance, in particular, a method in which the I preheating step is divided into three stages, is shown.

In FIG. 1, 1 is a mold, 2 and 3 are heating furnaces in preheating and curing processes, 4 is a cooling device, and 5 is a material. It is a heating furnace that heats from the front and back. Then, hot air supply devices Q, upper Q, lower Q, Q, as devices for making the mold temperature of the mold 1 appropriate for each process.
Q key and valve X, upper X, which adjusts hot air supply time
Lower X, X, X keys and a valve X cooling for adjusting the cooling water supply time are installed.

As a thermometer for measuring the temperature of a factor related to the rise and fall of the mold temperature, a thermometer T1, an upper T1, a lower T1, T1, T1 for measuring the mold temperature immediately before each step is used.
G, a thermometer T2 for measuring the temperature of the heat medium immediately before each step, upper T2, lower T2, T2, T2, and IV
Thermometer T2 for measuring the refrigerant temperature immediately before the cooling process
Cooling, and a thermometer T3 for measuring the temperature of the furnace inner wall immediately before each step, an upper T3, a lower T3, T3, T3 key,
A thermometer T4 for measuring the ambient temperature in the facility and a thermometer T5 for measuring the material temperature are installed.

In the powder slush molding equipment, the molding equipment 1 is moved in the direction of the arrow in each process equipment where the molding die 1 is online. In the heating furnace 2, hot air, which is a heating medium, is blown from one side of the mold 1 in the I preheating step from the furnace inner wall 2a, and the inside and outside (upper and lower) sides of the molding die 1 are heated from the furnace inner wall 2a in the I preheating step. Hot air is blown, and hot air as a heating medium is blown from the furnace inner wall 2a to one surface of the molding die 1 in the I preheating step so that the molding die 1 reaches a temperature α suitable for molding after the I preheating step. In addition, the heat medium supply device Q of each process, the upper Q
, Lower Q, Q and heat medium supply time adjusting valve X,
The hot air is adjusted by the upper X, lower X, and X to gradually raise the temperature.

Next, in the II molding step, the resin powder material 5 is attached to the molding die 1 heated to the temperature α suitable for molding, and in the III curing step, the molding die 1 is heated in the heating furnace 3.
Hot air, which is a heat medium, is blown from the furnace inner wall 3a to the mold while adjusting the mold temperature with the heat medium supply device Q and the heat medium supply time adjusting valve X to maintain the temperature β suitable for the cure. To do. Then, in the IV cooling step, the cooling water, which is the refrigerant, is adjusted by the cooling valve X for cooling the refrigerant supply time to be lowered to the temperature γ suitable for demolding, and then the V demolding is performed.

The mold temperature adjusting method according to the powder slush molding method of the present invention in such a powder slush molding facility has a temperature of a factor related to the rise and fall of the mold temperature obtained from the multiple regression equation in the multiple regression analysis and each step. In the relational expression shown in the equation 1 which is a relational expression with the amount of heat medium supplied in step 1 or the supply time of the heat medium or the refrigerant, The amount Q of the heat medium to be supplied or the supply time X, X cooling of the heat medium or the refrigerant is adjusted based on the calculated value.

[0016]

[Equation 1]

Here, T1, T2, T3, T4, and T5 represent factors related to the mold temperature, the heat medium or the refrigerant, the furnace inner wall, the atmosphere, and the mold temperature immediately before each step, respectively. The heat medium supply time X of the formulas 2 and 2'is a formula in the case where the calculated heat medium supply amount Q of the formulas 1 and 1'exceeds the maximum limit value and supplements the necessary heat amount by the supply time. The heating medium service time is a predetermined value. Formula 1, Formula 2 and Formula 1 ', Formula 2'are
As shown in FIG. 2, T6 (the mold temperature after the process) of the multiple regression equation described later is set to an appropriate mold temperature α, β (depending on the molding mold) so that the mold temperature draws a certain appropriate rising and falling curve. Different constant values) were obtained by setting the mold temperature of the multiple regression equation in the cooling process to the mold temperature γ (constant value that differs depending on the mold) suitable for the cooling process. It has been done. Also, the above A, A ', B, B'C, and a
To q and a ′ to q ′ are also constants set for each mold, which are derived by the multiple regression equation.

According to the powder slush molding method of the present invention as described above, it becomes easy to make the mold temperature of the molding die constant and appropriate for each step, and as a result, a good quality molded product is stabilized. Mass production is possible. By implementing the present invention, in a product with a strict color standard or a foamed powder slash with a strict hardness standard, the defective rate is 8 than that of the conventional product.
% From 0.5% to 0.5%, and with respect to ordinary products, the defective rate has drastically decreased from 3% to 0%.

Substitution of each measured value, amount of heat medium supplied,
Alternatively, the calculation of the supply time of the heat medium or the refrigerant is instantaneously performed for each process by the computer connected to each thermometer so that the heat medium or the refrigerant can be quickly adjusted based on the calculated value. Therefore, in order to keep the mold temperature after preheating within the allowable temperature range suitable for molding, the operator often sets the amount of heat medium to be supplied in each process, or the supply time of heat medium or refrigerant. There is no need to change the conditions.

For example, referring to Table 1, in the I preheating step, the measured value measured by the thermometer T1 is substituted as the mold temperature T1 before the step, and the heat medium temperature T2 is measured by the thermometer T2. The measured value measured by the thermometer T3 is substituted as the furnace inner wall temperature T3, the measured value measured by the thermometer T4 is substituted as the ambient temperature T4, and the thermometer is measured as the material temperature T5. The measurement value measured by T5 is substituted, and the heat medium supplying device Q or the valve X in the preheating I step is operated based on the heat medium supply amount or time calculated by the substitution of each measurement value. Shows.
In the powder slush molding method of the present invention, such a work is instantaneously performed in each step by a computer connected to each thermometer, and the heat medium and the refrigerant are quickly adjusted based on the calculated value. It has become so.

[0021]

[Table 1]

Here, a method of obtaining a relational expression quantitatively relating the temperature of a factor relating to the rise and fall of the mold temperature in each step and the amount of the heat medium to be supplied or the supply time of the heat medium or the refrigerant explain. As factors related to the rise and fall of the mold temperature, the mold temperature T1 immediately before each process and the heat medium or refrigerant temperature T2
And the temperature T3 of the furnace inner wall and the ambient temperature T4 of the equipment,
Taking the material temperature T5 and repeating various experiments,
In the preheating process and the curing process, the supply amount and time of the heating medium are expressed as a quadratic function of the mold temperature and the ambient temperature, and the heating medium temperature to be supplied, the furnace inner wall temperature, and the material temperature. It has been found that in the cooling step, the supply time of the refrigerant is expressed as a linear function of the ambient temperature and the refrigerant temperature.

Therefore, the multiple regression equation in the preheating I step is given by T6 = D + rQ + sX + tT1 ² + uT1 + vT2 + w
T3 + xT4 ² + yT4 + zT5 (where T1 is the mold temperature before the process, T6 is the mold temperature after the process, and D and r to z are constants that satisfy the multiple regression equation), and after each step of the multiple regression equation Q = E-rX-aT1 is obtained by setting the desired mold temperature α (constant that differs depending on the mold) after the preheating I step to the mold temperature T6 of No. 1 and further setting X = (predetermined time). ^2- bT1-cT2-dT3-eT4 ^2- fT4-gT5 ... 1 formula, and what sets Q = (highest value) is X = B-hT1 ² -jT1-kT2-1T3-mT4 ² -nT4 -OT5 ... It is a 2 type | formula.

III 'used in the III cure process
The formulas and 2'formulas are 1'formulas in which the desired mold temperature β (constant that differs depending on the molding mold) of the III curing process is set in T6 of the above multiple regression formula and further X = (predetermined time) is set. Yes, there is a formula 2'when Q = (highest value) is set.
Similarly, for the three equations used in the IV cooling step, the mold temperature of the multiple regression equation in the cooling step is set to the mold temperature γ suitable for the cooling step.
(Constant value that differs depending on the molding die). Here, A, A ′, B, B′C, and a to q
Then, a'to q'are constants set for each mold.

As a method of adjusting the mold temperature of the molding mold to an appropriate temperature for each step, not only hot air but also oil, metal powder or the like is used as a heating medium to heat the mold. In addition, the equipment form of the powder slush molding method is different from the online system described above, and has a heating, cooling medium path and adjusting function unique to each mold, and a modular system for supplying slush molding with a dedicated rotating device Even in
For each step, measure the temperature of the factors related to the rise and fall of the mold temperature, and substitute the measured value into the relational expression obtained by multiple regression analysis to determine the amount of heat medium or the supply time of heat medium or refrigerant. If the amount of the heat medium to be supplied in each of the steps, or the supply time of the heat medium or the refrigerant is varied and adjusted based on the calculated value, the mold temperature of the molding die is adjusted to a certain appropriate value for each step. Easy to reach temperature.

[0026]

As described above, according to the powder slush molding method of the present invention, the amount of the heat medium necessary to obtain an appropriate mold temperature in each step, or the supply time of the heat medium or the refrigerant is determined by multiple regression analysis. It can be calculated from the temperature of a factor related to the rise and fall of the mold temperature that is quantitatively related, and based on the calculated value, the amount of heat medium supplied for each process, or the supply time of the heat medium or refrigerant is changed. As a result, it becomes easy to set the mold temperature to a constant and appropriate temperature for each process, and as a result, it is possible to stably mass-produce high-quality molded products with the minimum required energy. Is.

[Brief description of drawings]

FIG. 1 is a diagram showing equipment of a powder slush molding method according to the present invention.

FIG. 2 is a graph showing a mold temperature rise / fall curve in the present invention.

FIG. 3 is a graph showing a conventional mold temperature rise / fall curve.

[Explanation of symbols]

1 Mold 2, 3 Heating Furnace 4 Cooling Device 5 Material I Preheating Process II Molding Process III Cure Process IV Cooling Process V Demolding Process T1, Upper T1, Lower T1, T1, T1 Key Thermometer T2, Upper T2, Lower T2, T2, T2 key heat medium thermometer T2 cold refrigerant thermometer T3, upper T3, lower T3, T3, T3 key furnace inner wall thermometer T4 atmosphere thermometer T5 material thermometer Q, upper Q, lower Q, Q, Q Hot air supply device X, upper X, lower X, X, X key, X cold valve

Claims (2)

[Claims] 1. A powder slush molding method, comprising a preheating step, a curing step, and a cooling step, for molding a product while supplying a heat medium or a refrigerant in each of the steps so as to obtain an appropriate mold temperature in each step, The temperature of the factor related to the rise and fall of the mold temperature is measured for each process, and the measured value is the temperature of the factor related to the rise and fall of the mold temperature previously obtained by the multiple regression analysis and the heat medium supplied in each process. Substituting in the relational expression with the amount, or the heating medium or the supply time of the refrigerant, the amount of the heating medium supplied in each step based on the value calculated in each step by this relational expression,
Alternatively, a powder slush molding method in which the supply time of the heat medium or the refrigerant is varied. 2. The temperature of a factor related to the rise and fall of the mold temperature obtained by multiple regression analysis and the amount of heat medium supplied in each step,
Alternatively, the relational expression with the supply time of the heat medium or the refrigerant, in the preheating step, the curing step, the supply amount of the heat medium or its supply time is a quadratic function of the mold temperature and the ambient temperature, and the heat medium temperature to be supplied, The powder slush molding method according to claim 1, wherein the temperature is expressed as a linear function of the furnace inner wall temperature and the material temperature, and in the cooling step, the supply time of the refrigerant is expressed as a linear function of the ambient temperature and the refrigerant temperature.