JP2000288625A - Extrusion control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a product excellent in surface quality by operating the supply of a refrigerant based on the temperature difference between the estimated product temperature based on the target extrusion speed obtained from the dimension and the extrusion ratio of a billet, and the treatment capacity of an extruder and the surface defect generation critical temperature, and adjusting the supply of the refrigerant. SOLUTION: When the temperature difference ΔT between the estimated product temperature Tv after extrusion and the surface defect generation critical temperature Tmax is larger then 0, the supply of the refrigerant is operated by a formula, and adjusted. In the formula, S1 denotes the supply of the refrigerant, ΔT is the required cooling temperature of the product, Sb is the sectional area of a billet, ϕb the diameter of the billet, Cb is the specific heat of the billet, ρb is the density of the billet, V* is the target extrusion speed, k is the ratio of the refrigerant used in cooling the product to the supplied refrigerant, q1 is the calorie to be removed by the refrigerant per unit weight, ρ1 is the density of the refrigerant and R is the extrusion ratio. The V* is obtained from the dimension and the extrusion ratio of the billet, and the capacity of the extruder, and the Tv is obtained based on the V*.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion control method for cooling a billet made of metal such as aluminum by using a coolant such as liquid nitrogen during extrusion.

[0002]

2. Description of the Related Art Generally, in a process of extruding a metal such as aluminum or aluminum alloy, a billet 3 in a container 10 is pushed from behind by a stem 9 as shown in FIG. Extruded.

In the production of this extruded product, it is desired to increase the extrusion speed in terms of production efficiency. On the other hand, when the extrusion speed is increased, the surface properties of some extruded products are deteriorated (surface defects such as cracks and tears are generated), so that extrusion at a low speed is inevitable, and the productivity (production amount per unit time) is increased. There is a problem that cannot be improved.

[0004] It is known that the deterioration of the surface properties of the extruded product is apt to occur as the temperature of the extruded product increases in the vicinity of the die outlet as the extrusion speed increases. In particular, it is known that the occurrence of surface defects is remarkable when the temperature of the extruded product exceeds a certain limit temperature (surface defect generation limit temperature).
For this reason, one of the measures for preventing the deterioration of the surface properties is to prevent the temperature of the extruded product from reaching the surface defect occurrence limit temperature.

[0005] From this viewpoint, in order to obtain a product having good surface properties, a method has been proposed in which the extrusion speed and billet heating temperature are adjusted and the temperature of the extruded product is controlled (for example, Japanese Patent Application Laid-Open No. Sho 61-1986).
No. 119324). In this method, as shown in FIG. 7, the temperature of the product 2 at the exit side of the die 4 is continuously measured by an infrared thermometer 14 provided at the exit side of the platen 13, and the measured product temperature is set in advance. In this method, the extrusion speed is constantly controlled so as to be equal to or lower than the surface defect limit temperature, and the billet temperature at the next extrusion is controlled.

However, in this method, the extrusion speed is controlled so that the measured product temperature is lower than the surface defect limit temperature, and the productivity cannot be improved by setting the extrusion speed higher than the control speed. There's a problem. For this reason, in order to obtain a product having good surface properties even at a high extrusion speed, a method has been proposed in which the vicinity of the die outlet is forcibly cooled with a refrigerant (air, gas, liquid nitrogen, etc.) to suppress a rise in the temperature of the product. JP-A-54-30667, JP-A-4-262821, etc.).

The method disclosed in Japanese Patent Publication No. 54-30667 is
As shown in FIG. 6, refrigerants 23a and 23b (air, CO ₂ gas, N ₂ gas, etc.) are supplied to both the inner periphery and the outer periphery of the extruded hollow product. 2
This is a method of adjusting the supply amount of the refrigerant based on the information from No. 4.
By maintaining the die hole 21c at a desired temperature with this refrigerant, product deterioration is prevented and the life of the die is extended. The method disclosed in JP-A-4-262821 is a method of continuously measuring the product temperature during extrusion with a radiation thermometer, and controlling the supply amount of the refrigerant based on the measured temperature value. That is, when the product temperature is higher than the set value, the coolant supply amount is increased, and when the product temperature is lower than the set value, the coolant supply amount is decreased. It is described that by repeating this, the product temperature during extrusion is kept at the optimum temperature, and as a result, a product of good quality is formed over the entire length in the product length direction.

[0008] These two methods are feedback control methods for controlling the supply of refrigerant based on online measured values (die temperature, container pressure, product temperature, etc.) during extrusion. That is, a coolant of a set flow rate is first flowed, the temperature of a die or a product is measured at the time of extrusion, and the coolant supply amount is controlled based on a difference between the measured temperature value and the set value.

[0009]

However, such a feedback control method requires an accurate temperature measuring device, a computing device having a high-speed processing capability, and the like, and the equipment cost is high. Further, there is a problem that maintenance for maintaining the performance of these apparatuses is troublesome, and the extrusion cost is increased. In addition, the measurement of the product temperature by a radiation thermometer is non-contact and is affected by the refrigerant used during extrusion, and the emissivity of the product surface due to the product surface roughness, alloy type, etc. In some cases, it is not always possible to accurately measure the product temperature due to a change in the temperature, and there is a problem that the refrigerant supply amount cannot be properly controlled.

Therefore, in the present invention, the initial setting of the refrigerant supply amount is performed by appropriate prediction without performing the feedback control in which the equipment cost is expensive, and a product having good surface quality can be obtained with good productivity as in the feedback control. It is another object of the present invention to provide an extrusion control method that can be produced at low cost.

[0011]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention relates to an extrusion control method for cooling an extruded product by a cooling medium supply means. Calculate the target extrusion speed from the extrusion ratio and the processing capacity of the extrusion device, predict the product temperature after extrusion based on the target extrusion speed, and calculate the predicted product temperature and the surface defect occurrence limit temperature of the product obtained in advance as the refrigerant. When the predicted product temperature is equal to or lower than the surface defect occurrence limit temperature, the refrigerant supply amount calculation means inputs a signal for setting the refrigerant supply amount to zero. On the other hand, when the predicted product temperature is higher than the surface defect occurrence limit temperature, the refrigerant supply amount is calculated based on the temperature difference between the predicted product temperature and the surface defect occurrence limit temperature, and the signal of the calculated value is output to the adjusting means. Output to the flow rate adjusting means, the flow rate adjusting means based on these output signals, is characterized in adjusting the refrigerant supply amount of the coolant supply unit.

By determining the target extrusion speed from the billet size, extrusion ratio and the processing capability of the extrusion device, the target extrusion speed at which the processing capability of the extrusion device is maximized can be set, and the productivity of extrusion can be increased. Can be maintained.

Next, the product temperature after extrusion is predicted on the basis of the target extrusion speed, and based on the predicted product temperature and the surface defect occurrence limit temperature of the product determined in advance, the refrigerant supply amount calculation means is operated. To perform the initial setting of the refrigerant supply amount,
By adjusting the refrigerant supply amount of the refrigerant supply means based on this setting, it is possible to extrude a product having good surface quality without the predicted product temperature exceeding the surface defect occurrence limit temperature. At this time, the prediction of the product temperature after extrusion can use an analogy value or a prediction formula from past actual values.
Then, the surface defect occurrence limit temperature of the product is measured in advance. Further, the local melting start temperature of the product can be adopted as the surface defect occurrence limit temperature of the product.

The coolant supply amount is initially set by the coolant supply amount calculating means, when the product temperature is equal to or lower than the surface defect occurrence limit temperature, the refrigerant supply amount is set to zero, and when the product temperature becomes the surface defect occurrence limit. When the temperature is higher than the temperature, by calculating the refrigerant supply amount based on the temperature difference between the product temperature and the surface defect occurrence limit temperature and adjusting the refrigerant supply amount of the refrigerant supply means, without causing surface defects on the product, The amount of refrigerant used can be minimized, and the production cost of extrusion can be reduced. At this time, the following prediction formula can be used for the calculation of the refrigerant supply amount in the refrigerant supply amount calculation means. S _l = (ΔT × S _b × C _b × ρ _b × v ^* ) / (60 × k × q _l × ρ _l × R) where S _l : refrigerant supply amount (m ³ / s) ^ΔT: the case of cooling required temperature (K) ΔT = 0 .... ( T v <T max of _{products) ΔT = T v -T max ....} ( in the case of T _v ≧ T _max) S _b : cross-sectional area of billet (m ² ) That is, S _b = (π / 4) × φ _b ² φ _b : billet diameter (mm) C _b : specific heat of billet (kcal / kg · K) ρ _b : Billet density (kg / m ³ ) T _v : Predicted product temperature after extrusion (K) T _max : Critical temperature at which surface defects occur in the product (K) v ^* : Target extrusion speed (m / min) k: Supplied refrigerant percentage used for product cooling of (0 <k <1) q l: heat refrigerant per unit weight may heat removal (kc
al / kg) ρ _l: density of the refrigerant (kg / m ³⁾ R: Extrusion ratio (the ratio of the sectional area of the cross-sectional area and the extruded product of the billet)

The prediction formula (formula) for the refrigerant supply amount _Sl was obtained as follows. First, the amount of heat Q _A (kcal) to be extracted for controlling the required cooling temperature ΔT of the product is: Q _A = C _b × ρ _b × ((π / 4) × φ _b ² × L _b ) × ΔT ... formula Here, L _b is and the length of the billet (mm), the amount of heat Q _B capable of heat removal the product when the feed amount S _l of the refrigerant in the billet extrusion (kcal) _{is, Q B = k × q l} × ρ _l × S _l × ((R × L _b ) / v ^* ) × 60. Here, k is the ratio of the supplied refrigerant used for cooling the product, and k is a variable between 0 and 1 depending on the extrusion conditions. From the formula and the formula, the refrigerant flow rate required to suppress the temperature rise ΔT of the product is Q _A = Q _B , and as a result, S _l = (ΔT × S _b × C _b × ρ _b × v ^* ) / ( 60 × k
× q _l × ρ _l × R).

According to a second aspect of the present invention, there is provided an extrusion control method for cooling an extruded product by a refrigerant supply means, wherein a target extrusion speed is determined based on a billet size, an extrusion ratio, and a processing capacity of an extrusion apparatus. The product temperature after extrusion is predicted based on the target extrusion speed, and the predicted product temperature and the previously determined surface defect occurrence limit temperature of the product are input to the refrigerant supply amount calculation means, and the refrigerant supply amount calculation is performed. Means are
When the predicted product temperature is lower than the surface defect occurrence limit temperature,
While the calculated value for making the refrigerant supply amount zero is output to the extrusion order determining means, when the predicted product temperature is higher than the surface defect occurrence limit temperature, the refrigerant is calculated based on the temperature difference between the predicted product temperature and the surface defect occurrence limit temperature. Calculate the supply amount and output the calculated value to the extrusion order determination means, wherein the extrusion order determination means
In the order of the calculated coolant supply amount, the extruding order of the billet before extrusion is rearranged, and the calculated coolant supply amount of the rearranged billet is stored, and then the billet is extruded in the rearranged order. At the time of extrusion, a signal of the refrigerant supply amount stored in the extrusion order determination means corresponding to the billet to be extruded is output to a flow rate adjustment means provided in the refrigerant supply means, and the flow rate adjustment means outputs these signals. The refrigerant supply amount of the refrigerant supply means is adjusted based on a signal.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, before the extrusion, the refrigerant supply amount of the billet before the extrusion is calculated in advance by the refrigerant supply amount calculating means. . Next, the extruding order judging means rearranges the extruding order of the billet before extruding in the order of the small refrigerant supply amount calculation value, and stores the refrigerant supply amount calculation value of the rearranged billet in the extrusion order judging means. I do. The billet is extruded in the rearranged order, and at the time of this extrusion, a signal of the calculated value of the refrigerant supply amount (stored in the extrusion order determining means) corresponding to the billet to be extruded is sent to the flow rate adjusting means. It outputs the output and adjusts the refrigerant supply amount of the refrigerant supply means based on the output signal.

By extruding the billet in ascending order of the calculated refrigerant supply amount, it is possible to (a) minimize the supply amount of the refrigerant. In other words, it is necessary to always fill the inside of the pipe between the refrigerant tank and the flow rate adjusting means with the refrigerant so that the refrigerant can be supplied at any time. Thus, the loss of the vaporized refrigerant can be reduced. Further, (b) it is possible to supply the refrigerant into the extruder so that the temperature of the extruded product does not exceed the surface defect occurrence limit temperature, and it is possible to extrude a product having good surface quality stably. That is, the inside of the pipe between the refrigerant tank and the flow rate adjusting means is sufficiently cooled in advance, and a predetermined amount of the refrigerant can always be supplied into the extruder, thereby preventing the occurrence of surface defects of the extruded product. Conventionally, products with and without cooling were performed in a mixed production order.If a billet for products with cooling required was extruded after a product with no cooling required, the piping was In some cases, the extruder was not sufficiently cooled, and the refrigerant was vaporized in the pipe and a predetermined amount of the refrigerant could not be supplied into the extruder. The invention according to claim 2 is to extrude billets in ascending order of the refrigerant supply amount calculation value based on the initial setting of the refrigerant supply amount by appropriate prediction,
A product with good surface quality can be produced with good productivity and at low cost.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to illustrated examples. FIG. 1 is an explanatory diagram of an extruder used in the extrusion control method of the present invention. FIG. 2 is a flowchart showing a control method of the first embodiment of the present invention.
FIG. 4 is a flowchart showing a control method according to the second embodiment of the present invention.

As shown in FIG. 1, the extruder 1 used in the extrusion control method of the present invention includes a liquid nitrogen storage tank 6 and a liquid nitrogen storage tank 6 connected to a liquid nitrogen pipe 7a. Regulating valve 7b and this liquid nitrogen regulating valve 7b
And a cooling medium supply means 7 comprising a liquid nitrogen flow passage 7c having an opening 7d between the die 4 in the extruder 1 and the backer 10. This cooling medium supply means 7
Liquid nitrogen is released from the opening 7d, and the product 2 after extrusion is discharged.
In addition to cooling the die, the die 4 can also be cooled.

In the extruder 1, an input means 5 and a calculation means 8 are provided, and a liquid nitrogen adjusting valve 7b of a refrigerant supply means for cooling the extruded product is provided with a flow rate for controlling a refrigerant supply amount. Adjusting means is provided. The input means 5 is a device for inputting billet dimensions, extrusion ratio, processing capability of an extrusion device, and a surface defect occurrence limit temperature of a product obtained in advance. The calculating means 8 includes an extrusion speed calculating means 8a, a temperature estimating means 8b and a refrigerant supply amount calculating means 8c.

The extruding speed calculating means 8a calculates a target extruding speed from the information of the billet dimensions, the extruding ratio and the processing capacity of the extruder input to the input means 5. Next, the temperature predicting means 8b predicts the product temperature after extrusion based on the target extrusion speed obtained by the extrusion speed calculating means 8a. Then, the refrigerant supply amount calculating means 8c calculates the refrigerant supply amount from the product temperature predicted by the temperature prediction means 8b and the surface defect occurrence limit temperature input to the input means 5. Thereafter, a signal of the refrigerant supply amount calculated by the refrigerant supply amount calculating means 8c is sent to the liquid nitrogen adjusting valve (flow rate adjusting means) 7b, and the flow rate adjusting means 7b controls the cooling medium so as to reach the calculated refrigerant supply amount. The supply means 7 is controlled.

Next, a first embodiment of the present invention (the invention of claim 1) in which the extruder is used to control the supply amount of refrigerant during extrusion will be described with reference to FIG. First, in [Step 1], the number of extrusions is set to M. Then, the coefficient K of the number of extrusions is set to zero.

In [Step 2], the following extruded product information is fetched by the input means. The dimensions of the billet (mm): L _b (length), phi _b (diameter) extrusion ratio: capacity of R extruder (kg / min): d product surface defects limit temperature (° C.): T _max, where The billet has a generally cylindrical shape, but may have a prismatic shape. Is the ratio of the cross-sectional area of the billet to the cross-sectional area of the extruded product. In regard to the processing capacity d of the extruder, the processing capacity of the equipment before and after the extruder is also taken into consideration. For example, taking into account the processing capacity of the front equipment (such as the heat treatment capacity of the billet) a and the processing capacity of the rear equipment (processing capacity such as pulling force, cutting of products, etc.) b, the processing capacity that determines the rate is defined as the processing capacity d of the extruder. Is preferred. The surface defect occurrence limit temperature _Tmax of the product is obtained in advance from the results of actual operation and experiments. Further, the local melting start temperature of the product can be adopted as the surface defect occurrence limit temperature of the product.

In [Step 3], the target extrusion speed v ^* is determined by the extrusion speed calculation means. The following arithmetic expression can be used to determine the target extrusion speed (m / min): v ^* . _{^{v * = (L b × R}} × d) / in _{(S b × L b × ρ} b -d × c) where, S _b: cross-sectional area of the billet (m ²⁾ That _{is, S b = (π / 4} ) × φ _b ² φ _b : billet diameter (mm) L _b : billet length (mm) ρ _b : billet density (kg / m ³ ) R: extrusion ratio d: processing capacity of extrusion device (kg / min) ) C: Setting time per billet (kg
/ Min)

Next, in [Step 4], the product temperature T _v after extrusion is predicted by the temperature predicting means. The predicted product temperature after this extrusion is estimated from the past actual value,
A prediction formula can be used. For example, the predicted product temperature T
_v is extrusion speed v ^*, it can be calculated by the prediction equation of the formula as a function of such billet temperature theta _{b. T v = θ b + Δθ 1} - ((H × R) / C b × ρ b × S b
_{^{× v *) × (θ b}} + (Δθ 1/2) -θ d) _{However, Δθ 1 = (F s ×} J -1 / (C b × ρ b × S b) where, T _v: predicted product Temperature (° C.) θ _b : Billet temperature (° C.) θ _d : Die heating temperature (° C.) v ^* : Extrusion speed (m / min) H: Heat transfer rate from extruded material to tool (kcal /
min · ° C.) S _b : cross-sectional area of billet (mm ² ) That is, S _b = (π / 4) × φ _b ² C _b : specific heat of material (kcal / kg · K) ρ _b : density of material (kg / M ³ ) F _s : extrusion load (predicted value or actual value) (kgf) J: heat equivalent of heat (kgf / m / kcal) At this time, the billet temperature θ _b is the temperature taken out from the billet heating furnace, the die As the heating temperature θ _d , a set die heating temperature at the time of ordinary extrusion can be adopted.

[0027] Then, the extrusion load F _s to be used for calculation of the predicted product temperature T _v, when the extrusion of aluminum (including aluminum alloys.), Can be used extrusion final load. The load-displacement curve for aluminum is generally shown in FIG. Here, part B in the figure represents the amount of work required for processing (deformation) of the material, and part A in the figure represents the amount of work required for friction between the container and the billet. Usually, an increase in product temperature during extrusion processing is mainly caused by processing heat (B) near the exit of the mold. Therefore, it is possible to use extrusion final load which can be determined only by the B portion to the calculation of the predicted product temperature T _v.

[0028] Then, in Step 5: By refrigerant supply amount calculating means, and it compares the surface defect generation temperature T _max and predicted product temperature T _v after extrusion. ΔT = T _max −T
_{When v} ≦ 0, that is, when it is determined that cooling is unnecessary, the coolant supply amount is set to zero in [Step 6]. On the other hand, when ΔT = _Tmax − _Tv > 0, that is, when it is determined that cooling is necessary, in [Step 7],
The required refrigerant supply amount is calculated by the refrigerant supply amount calculation means. Then, these results are obtained in [Step 8].
The required refrigerant supply amount is output from the refrigerant supply amount calculation means to the flow rate adjusting means. At this time, if it is determined that the refrigerant supply amount is zero, that is, if it is determined that cooling is unnecessary, no refrigerant supply is performed. When it is determined that cooling is necessary, the liquid supply amount is supplied to the extruder by adjusting the liquid nitrogen control valve (flow rate control means) 7b of the refrigerant supply means so that the output refrigerant supply amount is obtained. I do.

In [Step 9], if K ≠ M, return to [Step 1], set K = K + 1, and
[Step 2] The subsequent steps are executed again. And
In [Step 9], the process ends when K = M. In this way, the initial setting of the coolant supply amount can be performed by appropriate prediction, and a product having good surface quality after extrusion can be produced.

Next, a description will be given of a second embodiment of the present invention (the invention of claim 2) in which the extruder is used to control the supply amount of refrigerant during extrusion. In the second embodiment of the present invention, an extruder in which the extrusion control method of the present invention shown in FIG. 1 is added to the first embodiment of the present invention is further provided with an extrusion order determining means.

A second embodiment (the invention of claim 2) of the present invention will be described with reference to FIGS. [Step 1]
In, M is set as the number of extrusions. Then, the coefficient K of the number of extrusions is set to zero. Then, the steps of the first embodiment of the present invention ([Step 2] to [Step 8])
Is repeatedly executed. Then, at this time [Step 8]
Then, the required refrigerant supply amount obtained by the refrigerant supply amount calculation means is output to the extrusion order determination means.

Then, in [Step 9], K ≠ M
If so, return to [Step 1], set K = K + 1, and execute the steps from [Step 2] onward. Then, at step 9 when K = M,
[Step 10] is executed.

In [Step 10], the extrusion order determining means determines whether cooling is necessary or not to achieve the target extrusion speed, and determines the product group of the M types of products that do not require cooling. And product groups that require cooling, and total the number of product types for each. For example, the type of product group that does not require cooling: N The type of product group that requires cooling: MN

Next, in [Step 11], a production order is determined for product groups (N types) that do not require cooling. In this case, there is no particular restriction on the order, and a conventional extrusion schedule may be used. Then, the production order is determined for the products (MN types) of the product group requiring cooling. In this case, the extruding order determining means rearranges the extruding order of the billets before extrusion in ascending order of the refrigerant supply amount calculated by the refrigerant supply amount calculating means, and extrudes the calculated refrigerant supply amount of the rearranged billet. It is stored in the order determining means.

In [Step 12], N is set as the type of product group that does not require cooling, that is, the number of extrusions. Then, the coefficient I of the number of extrusions is set to zero. Thereafter, in [Step 13] and [Step 14], the billet is extruded.

After the end of billet extrusion, [Step 15]
If I へ N, return to [Step 12] and return to I
= I + 1, and the processes after [Step 13] are executed again. Then, in [Step 15], I
When N = N, the process proceeds to [Step 16], and the extrusion of the billet of the product group that does not require cooling is ended.

Next, extrusion of the group of billets requiring cooling is started. In [Step 16], N is set as the number of extrusions. Then, the coefficient J of the number of extrusions is set to zero. Then, in [Step 17], while extruding the billet, the liquid nitrogen adjusting valve (flow rate adjusting means) 7b of the refrigerant supplying means is adjusted based on the set value of the refrigerant supply amount stored in the extrusion order determining means. To supply the refrigerant supply amount into the extruder ([Step 18]). When the extrusion of the billet is completed in [Step 19], the supply of the refrigerant to the extruder is stopped ([Step 20]).

Then, the process proceeds to [Step 21].
If −N, return to [Step 16], set J = J + 1, and execute the steps after [Step 17] again. Then, when J = M−N in [Step 21], the process proceeds to [Step 22], and the supply of the refrigerant from the refrigeration tank to the pipe is stopped simultaneously with the end of the extrusion of the billet of the group requiring cooling.

In the present embodiment, [Step 14]
Between [Step 15] and [Step 15], a newly provided [Step A] determination means and [Step B] refrigerant supply process from the storage tank to the pipe can be newly provided. That is, when the number of billets in the product group that does not require cooling becomes small, the refrigerant is supplied to pipes and the like in preparation for extruding billets in the group that needs cooling. For example, in the determination means in [Step A], when the number of remaining billets is five, that is, when I> N−5, the process proceeds to [Step B] and the supply of the refrigerant to the pipes and the like is started. Can be. Also in this case, next, [Step 15]
It will go to. By [Step 14] and [Step 15], the stable supply of the refrigerant becomes possible immediately after the start of cooling.

Next, an extrusion experiment according to the above-described embodiment was performed using the extruder shown in FIG. This extrusion experiment
Using a billet (dimensions: φ250 mm) made of an aluminum alloy (JIS 7N01 series), a hollow product of complicated shape A (extrusion ratio: 75), a square bar of B (extrusion ratio: 50), a square pipe of C (extrusion ratio: 70) ), A 1-ton extrusion experiment was performed. The cross-sectional shape of these extruded products is shown in FIG. FIG.
FIG. 2A is a view showing a cross section of a hollow product having a complicated shape of A.
FIG. B is a diagram showing a cross section of a square rod of B, and FIG. C is a diagram showing a cross section of a square pipe of C.

(First Extrusion Experiment: Conventional Example) Based on the above-mentioned billet dimensions, extrusion ratio, and processing capacity of the extrusion device, the target extrusion speed (complex hollow product of A: 17 m / min, square bar of B: 25 m / min) , C square pipe: 20 m / min)
I asked. In this extrusion experiment, the amount of refrigerant (liquid nitrogen) was set at 100 kg per ton, which is a general usage amount. Then, the above-described target extrusion speed and the cooling medium are supplied at a rate of 100 kg /
Using 1 ton of product, extrusion was performed in the order of hollow product of complicated shape A, square bar B, and square pipe C. Inspection of the surface condition of the product after extrusion revealed that surface defects occurred in all of the extruded hollow products of complex shape A. On the other hand, no surface defects were observed on the square rod B and the square pipe C.

(Second Extrusion Experiment: Invention of Claim 1) The product temperature after extrusion is predicted based on the target extrusion speed described above, and the predicted product temperature and the surface defect occurrence limit temperature of the product obtained in advance (for example, The refrigerant supply amount was calculated based on the temperature difference from the local melting start temperature. The calculated refrigerant supply amount is as follows. A-shaped hollow product of A: 150 kg / ton of product B square bar: No supply required. C square pipe: 80 kg / one ton of product At the above-mentioned target extrusion speed, a refrigerant of the calculated refrigerant supply amount is supplied to form a hollow product of complicated shape A, a square rod of B, and a square pipe of C. Extrusion was performed in order. Inspection of the surface condition of the extruded product revealed that surface defects occurred in the first few products of the hollow product of complex shape A, but the product after stable coolant supply showed no surface defects. No occurrence was observed. On the other hand, no surface defects were observed on the square rod B and the square pipe C. As described above, even if the coolant supply amount at the time of extrusion of the square rod of B or the square pipe of C is reduced from the coolant supply amount at the time of general extrusion (100 kg / ton of product), the square rod of B or C It was confirmed that surface defects did not occur in the square pipe.

(Third Extrusion Experiment: The Invention of Claim 2) In the present extrusion experiment, the extrusion order of the product was changed under the conditions of the second extrusion experiment. The extrusion was performed in ascending order of the refrigerant supply amount, that is, in the order of the square bar of B, the square pipe of C, and the hollow product of the complicated shape of A. When the surface condition of the product after extrusion was inspected, no surface defect was observed in any of the products.
As described above, it was confirmed that by rearranging the billet extruding order before the extrusion in the order of the small amount of the supplied refrigerant, it is possible to prevent surface defects of the product and to reduce the amount of the refrigerant used.

As described above, without performing feedback control, the initial setting of the refrigerant supply amount is performed by proper prediction, and the extrusion order of the products before extrusion is rearranged in the order of the calculated refrigerant supply amount, and By supplying the refrigerant having the calculated value into the extruder (near the product outlet of the die) at the time of extrusion, an extruded product having good surface quality could be produced with good productivity and at low cost.

[0045]

As described above, according to the present invention, the initial setting of the supply amount of the refrigerant is performed by appropriate prediction without performing the feedback control in which the equipment cost is expensive. This makes it possible to control extrusion for producing a simple product with good productivity and at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an extruder incorporating an extrusion control method of the present invention.

FIG. 2 shows a control method according to the first embodiment of the present invention.
It is a figure which shows a flowchart.

FIG. 3 shows a control method according to a second embodiment of the present invention.
It is a figure showing the first half of a flow chart.

FIG. 4 shows a control method according to a second embodiment of the present invention.
It is a figure which shows the latter half of a flowchart.

FIG. 5 is a piping model diagram of an extruder for cooling liquid nitrogen.

FIG. 6 is a schematic diagram showing the supply of refrigerant to an extruded product and a die according to the prior art.

FIG. 7 is an explanatory view schematically showing a conventional extruder and a radiation thermometer.

FIG. 8 is a diagram showing a load-displacement curve of aluminum.

9 is a diagram showing a cross-section of an extruded product according to an embodiment of the present invention, FIG. 9A is a cross-sectional diagram of a hollow product having a complicated shape of A, FIG. 9B is a cross-sectional diagram of a square bar of FIG. c is a sectional view of a C square pipe.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 extruder 2 extruded product 3 billet 4 die 5 input device 6 flow rate regulating valve (flow rate regulating means) 7 refrigerant supply means 8 computing means 8a extrusion speed computing device 8b product temperature prediction device 8c refrigerant supply amount computing device 8d extrusion sequence determining means 9 Stem 10 Container 11 Backer 12 Bolster 13 Platen 14 Radiation thermometer (infrared radiation thermometer) 15 Liquid nitrogen storage tank 16 Subcooler 17 Flow control valve 18 Control panel 19 Liquid nitrogen pipe 20 Gas working pipe 21a Male dice 21b Female dice 21c Die hole 22 Refrigerant flow path 23 Flow control valve 23a Refrigerant 23b Refrigerant 24 Temperature measuring instrument 25 Extruded product

Continued on the front page (72) Inventor Katsuhiko Inoue 14-1, Chofu Minatomachi, Shimonoseki-shi, Yamaguchi F-term in Kobe Steel, Ltd. Chofu Works (reference) 4E029 SA02 SA03 TA02 TA05 TA05 TA06 TA07

Claims (2)

[Claims] In an extrusion control method for cooling an extruded product by a refrigerant supply means, a target extrusion speed is determined from a billet size, an extrusion ratio, and a processing capacity of an extrusion device, and the target extrusion speed is determined based on the target extrusion speed. The product temperature is predicted, and the predicted product temperature and the previously determined surface defect occurrence limit temperature of the product are input to the refrigerant supply amount calculating means. When the temperature is the same or lower, a signal for setting the refrigerant supply amount to zero is output to the flow rate adjusting means provided in the refrigerant supply means, while when the predicted product temperature is higher than the surface defect occurrence limit temperature, the predicted product temperature and the surface The refrigerant supply amount is calculated based on the temperature difference from the defect occurrence limit temperature, and a signal of the calculated value is output to the flow rate adjusting unit.The flow rate adjusting unit is configured to output a signal based on these output signals. Extrusion control method characterized by adjusting the refrigerant supply amount of the coolant supply unit. 2. An extrusion control method for cooling an extruded product by a coolant supply means, wherein a target extrusion speed is obtained from a billet size, an extrusion ratio, and a processing capacity of an extruder, and the target extrusion speed is determined based on the target extrusion speed. The product temperature is predicted, and the predicted product temperature and the previously determined surface defect occurrence limit temperature of the product are input to the refrigerant supply amount calculating means. When the same or lower, while the calculated value to make the refrigerant supply amount zero is output to the extrusion order determination means, when the predicted product temperature is higher than the surface defect occurrence limit temperature, the predicted product temperature and the surface defect occurrence limit temperature Calculates the refrigerant supply amount based on the temperature difference of the above and outputs the calculated value to the extrusion order determination means. The extrusion order determination means determines the billet before extrusion in ascending order of the calculated refrigerant supply amount. The rearrangement of the extruding order and the storing of the calculated refrigerant supply amount of the rearranged billet are performed. Next, the billet is extruded in the rearranged order. A signal of the refrigerant supply amount stored in the extrusion order determining means is output to a flow rate adjusting means provided in the refrigerant supplying means, and the flow rate adjusting means, based on these output signals, supplies a refrigerant supply amount of the refrigerant supplying means. And controlling the extrusion.