JPH02294424A - Method and apparatus for quenching casting - Google Patents

Abstract

PURPOSE:To make uniform cooling velocity of plural castings regardless of kind and position of the castings and to restrain warp and residual strain of the casting by detecting cooling water temps. among castings in a water vessel at the time of quenching and controlling cooling water flow rates spouted to among the castings based on the above. CONSTITUTION:At the time of quenching the heated castings 3a, 3b, 3c, the cooling water temps. among the castings 3a, 3b, 3c in the water vessel 1 are measured with temp. sensors 4-7 and these results are inputted into control means 29. On the other hand, spray nozzles 8-11 set in the water vessel 1 are fixed so as to inject water flow to each interval among the castings 3a, 3b, 3c and outside of the castings 3a, 3c at the outer most side. Based on output signal of opening degree for each flow rate control valve 12, 14, 16, 18 calculated with the control means 29, the opening degree of each valve 12, 14, 16, 18 is controlled to control the spraying water rates from the above nozzles 8-11 and the cooling velocity of each casting 3a, 3b, 3c is made uniform.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for quenching a casting using cooling water, and more particularly to a quenching method and apparatus for suppressing warpage and distortion of the casting during quenching. .

[Prior Art] As a prior art related to the present invention, for example, Japanese Patent Laid-Open No. 62
-256920 and JP-A-63-149313 are known. The former method sets targets for the transformation rate pattern and temperature pattern, determines the corresponding temperature from the transformation rate and elapsed time of the steel material detected at multiple points, and changes the history of cooling water injection. Cooling is performed according to a transformation rate pattern. The latter is equipped with a control circuit that continuously detects the temperature change of the heated object during cooling and slowly cools the heated object when the temperature reaches the martenreith transformation starting temperature. This makes it possible to obtain the required quenching hardness while having a low momme.

FIG. 8 shows an example of an apparatus used in a conventional method for hardening aluminum castings. In the figure, 50 indicates a hardening furnace, and a hardening elevator 51 is arranged on one side of the hardening furnace 50. Hardening furnace 50 of hardening elevator 51
A return furnace 52 is arranged on the opposite side. Directly below the quenching elevator 51, a water tank (quenching water tank) 1 is formed. The quenching elevator 51 is for castings 3a to
The heat treatment tray 2 accommodating the heat treatment tray 3d is raised and lowered relative to the water tank 1. A plurality of spray nozzles 8 to 11 are arranged in the water tank 1 to spray cooling water into the water tank 1. The upper part of water tank 1 and each spray nozzle 8 to 11
are connected via a circulation pump 20, and the cooling water in the water tank 1 is circulated by this circulation pump 20.

In a method for quenching aluminum castings using such an apparatus, when the treatment in the quenching furnace 50 is completed, the castings 38 to 38
3d is carried out of the furnace together with the heat treatment tray 2. Then, the castings 3a to 3d are immersed in cooling water in the water tank 1 together with the heat treatment tray 2 by the quenching elevator 51. In this state, cooling water is ejected from each of the spray nozzles 8 to 11 into the water tank 1, and each casting 3a to 3d is cooled and hardened by this cooling water flow.

For example, when the cast metal is an engine cylinder head, about 40 cylinder heads are usually housed in the heat treatment tray 2, and each cylinder head is hardened in a vertical position for the purpose of uniform cooling.

[Problems to be Solved by the Invention] However, the first quenching method shown in FIG. 8 also had the following problems.

B) Cooling water is heated by the heat of the castings, and steam is generated between the castings, impeding heat conduction. Moreover, since the water flow from the spray nozzle is constant regardless of the cooling state of the casting, the cooling rate of the casting becomes non-uniform, causing problems in dimensional accuracy due to warping and cracking due to residual strain.

Usually, multiple types of castings are treated in the same heat treatment furnace, but since the water flow from the spray nozzle is constant regardless of the type of casting, R is suitable for castings with different capacities, weights, and shapes. I can't respond.

f9 If the water flow from the spray nozzle is increased, problems such as warpage and distortion can be solved to some extent, but energy is wasted and the work is blown out of the heat treatment tray by the force of the water.

The operating time of the spray pump is controlled by a timer, but in order to have enough margin, it is kept running even after it has cooled down sufficiently, which wastes energy.

As described above, it is difficult to improve the quality of the casting as described above simply by submerging the casting in a water tank in which cooling water is circulated.

In view of the above-mentioned problems, the present invention makes the cooling speed of a plurality of castings uniform regardless of the type and location of the castings, and prevents warping of the castings.
It is an object of the present invention to provide a hardening method and apparatus that can suppress residual strain.

[Means for Solving the Problems] A casting quenching method according to the present invention that meets this objective includes immersing a plurality of heated castings in cooling water in a water tank, and squirting the plurality of castings into the water tank. Cooled by cooling water,
In the method of quenching the casting, the temperature of cooling water between the castings in the water tank is detected during the quenching, and the flow rate of cooling water jetted between the castings in the water tank is controlled based on the detected cooling water temperature. Consists of.

Further, the casting quenching apparatus according to the present invention includes: a water tank in which the heated casting is immersed; a spray nozzle arranged in the water tank and spouting cooling water into the water tank; and a spray nozzle connected to the spray nozzle and connected to the water tank. a circulation pump that circulates cooling water in the water tank; a flow rate control valve connected to the spray nozzle; a temperature sensor that is placed in the water tank and detects the temperature of the cooling water in the water tank; control means for controlling the opening degree of the flow control valve based on a signal from the flow control valve.

1 Effect] In such a casting quenching method, the temperature of the cooling water between the castings in the water tank is not detected during quenching, so it is possible to judge how cold the castings are FJJ based on this cooling water temperature. In this case, if cooling is insufficient, the amount of cooling water jetted between the castings is increased to promote cooling of the castings. On the other hand, if the area continues to be cooled more than the squared area, the amount of cooling water is reduced. In this way, by appropriately controlling the flow of cooling water jetted between the castings, it becomes possible to equalize the cooling rate of each casting, thereby suppressing warpage and residual distortion of the castings.

[Embodiment 1] Below, a preferred embodiment of the casting quenching method and apparatus according to the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of the present invention. The structure of the water tank J3 and its vicinity in the apparatus used in this embodiment is similar to the conventional structure shown in FIG. 8, so the explanation of the corresponding parts will be explained by assigning the same numbers as in FIG. 8 to the corresponding parts. This will be omitted and only the different parts will be explained.

(Later) The same applies to the example of Haku.

In FIG. 1, a casting 3a accommodated in a heat treatment tray 2
, 3b and 3c are immersed in cooling water. Humidity sensors 1 and 4 are installed between one side surface 2a of the heat treatment tray 2 and the casting 3a.

A temperature sensor +J5 is arranged between the castings 3a and 3b, and a temperature sensor 1-6 is arranged between the castings 3b and 3C. Similarly, the side surface 2 of the heat treatment tray 2
A temperature sensor 7 is arranged between the casting member 3C and the casting member 3C.

Each temperature sensor 4, 5, 6, 7 is arranged so that it can pass through the gap on the bottom of the heat treatment tray 2 when the heat treatment tray 2 is lowered, and when the heat treatment tray reaches the lowering end,
Between each work 3a, 3b, 3C and the outermost work 3
Temperature sensors 4, 5, 6, 7 arranged to measure the water temperature outside a, 3c are respectively connected to temperature sensors 21, 22, 23, 24 of the control means 29;
The temperature measurement results of each temperature sensor 1 are sent to this control φI means 2.
9 is input.

At the bottom of the water tank 1 are spray nozzles 8, 9, 10, 11.
The spray nozzles 8 to 11 are arranged between each casting 3a, 3b, 3c and between the outermost workpiece 3.
Spray water on the outside of a and 3c! }It is fixed like a J. Each spray nozzle 8, 9, 10, 11 has a circulation pump 20 and a flow control valve 12, 14, 16, respectively.
, 18, and communicates with the upper part of the water tank 1.

Each flow control valve 12, 14, 16, 18 has a control motor 13, 15, 17, which controls the valve opening degree.
19 each, and each control has one motor 1 per day.
3, 15, 17, and 19 are connected to valve control signal terminals 25, 26, 27, and 28 of the control means 29. Each control motor 13, 15, 17, 19 operates each flow rate control valve 1 in response to a valve open 1 output signal operated by a control means 29 based on the temperature measurement results of temperature sensors 1, 4 to 7.
The opening degrees of valves 2, 14, 16, and 18 are controlled to control the amount of water sprayed from the spray nozzle.

FIG. 2 shows a flowchart showing the procedure of the Korean method within the control means 29. As shown in the figure, before the heat treatment tray 2 starts descending into the water tank 1, a start signal is issued in step 31 to wait until the water volume of the circulation pump 20 is stabilized, and the process proceeds to step 32. At step 32, full flow control valves 12, 1
A control signal is issued to set the opening degrees of the openings 4, 16, and 18 to the initial opening values, and the circulation pump 20 is operated in step 33. Next, the process proceeds to step 34, where the temperature measurement result of the temperature sensor +)4 is input, and in step 35, the temperature information is converted into a valve opening degree. Next, the process advances to step 36, where the control motor 1 receives an opening/closing signal for the valve 12.
Output the control signal to 3. Thirst Sadasen 1J5, 6, 7
Similar processing is performed for (steps 37 to 45)
In step 46, each temperature measurement result T4, T5, TI! , T7 are all smaller than the cooling stop temperature "stop", and if they are smaller, the circulation pump 20 is stopped, and if not, the temperature measurement result of the temperature sensor 4 is input again and the same process is repeated.

An example of a method for converting temperature information into a valve opening degree is to convert the standard valve opening degree Vs corresponding to the standard temperature 'std.
td is determined, and the valve distance V = V Std X (Temperature measurement result 1-)
÷'Std Alternatively, using the sensitivity coefficient α, the valve opening degree V=Vstd x (1+αX(temperature measurement result T
-TStd) ``std)'' can be used to determine the valve opening degree.

In addition, the temperature measurement results T4, TS, Te,
Compare whether all Tr are smaller than the cooling stop temperature TstopJ: and if it is smaller, stop the circulation pump 20. This is because even though the casting has been sufficiently cooled, the pump is kept running for safety reasons, which is a waste of energy. This is to prevent losses.

In this way, the temperature sensor 4J4 placed near each casting
, 5, 6, and 7, the flow of cooling water jetted from each spray nozzle 8, 9, 10, and 11 is controlled, so that the cooling rate of each casting 3a13b, 3c is The quality of the castings is improved by making them uniform, suppressing dispersion in waste and residual strain between castings, and improving the quality of the castings. Note that even if the type of casting changes and the water temperature conditions in the heat treatment tray 2 change, a uniform cooling rate can be obtained by controlling the amount of cooling water without being affected by changes in water temperature.

In addition, due to the second problem of quality, in the conventional method, it is necessary to set the spray level according to the part of the casting that is the most difficult to cool among the many types of castings, and the part that is cooled the most. The amount of sprayed water is excessive, which causes a lot of energy loss and increases the difference in cooling rate between the workpieces, but the sprayed water ω is controlled depending on the water temperature of the casting
This greatly reduces energy loss.

Spraying is automatically stopped when the water temperature drops below the spray stop temperature, so the pump's operating energy is not wasted, and it also prevents the pump from stopping without sufficient cooling, which can lead to quality problems. occurrence is prevented.

Second Embodiment FIGS. 3 and 4 show a second embodiment of the present invention. Since the formation of the hardening apparatus in the second embodiment is similar to that in the first embodiment, the explanation thereof will be omitted, and only the difference in method will be explained.

FIG. 3 shows the procedure of the calculation method inside the control means 29 in FIG. Before the heat treatment tray 2 starts lowering into the water tank 1, the circulation pump 2 is activated in step 130.
A start signal is issued in anticipation of the time until the level of 0 becomes stable, and the process proceeds to step 131. In step 131, a control signal is output to set the opening degrees of the flow control valves 12, 14, 16, and 18 to initial values, and step 1
At 32, the circulation pump 20 is put into operation. Next, the temperature measurement results of temperature sensors 4, 5, 6, 7 Ta, Ts, Te,
Ty is input, and in step 133 T4 is first compared with the spray stop temperature Tstop. If it is smaller, the process proceeds to step 134 and the opening degree of the valve 12 is set to the minimum. If it is larger, the process proceeds to step 135 and (T4 Ts) is determined as the minimum temperature difference. Compare with K. The result in step 135 (T4
-rs) is larger than K, the process proceeds to step 136, where the opening degree of the valve 12 is opened by one step, and if it is smaller, step 13
Step 7 compares (T5-T.) with the minimum temperature difference K.

If the result (Ts Ts) in step 137 is greater than the minimum humidity difference K, the process proceeds to step 138 and the valve 12
Close the opening degree by one step, and if it is smaller, proceed to step 139 and compare T5 with the spray stop temperature "stop".The same process (steps 140 to 148) is performed thereafter, and each temperature measurement result Ts is , Ts , T
oNT? It is compared in step 149 whether all of them are lower than the spray stop temperature 'stop, and if it is, the pump 20 is stopped in step 150. If not, the temperature measurement results of temperature sensors 4, 5, 6, and 7 are checked again. Input,
Repeat the same process. The minimum temperature difference K forms a dead zone, and its appropriate value is determined depending on the characteristics of the control system.

In this example, regardless of the magnitude of the humidity difference between the two points with the workpiece in between, the valve level is controlled by opening and closing one step at a time, but since the time required for one cycle is very short, Although the opening degree is appropriate and there is no problem in practical use, the temperature difference between the two points sandwiching the casting is compared with a preset value, as shown in steps 151 to 159 of the modified example in Fig. 4, and the result is If the opening degree of the valve is opened and closed by the corresponding number of stages, it will be even faster (it is advantageous to make an appropriate valve opening mark).In other words, if the program shown in step 158 is incorporated into the control means 29, , fine-grained flow control Il
1 is increased by 1q, and the cooling rate of the casting can be made uniform with high precision.

In addition, the temperature measurement results T4, T's, 16 after each cycle are completed.
, Tstop is smaller than the cooling stop temperature Tstop, and if it is smaller, the pump 20 is stopped for safety reasons even though the workpiece has been sufficiently cooled because it is controlled by a timer as in the first embodiment. This is to prevent energy loss due to excessive pump operation.

In addition, in this example, the quenching water temperature is sufficiently low to ensure the minimum amount of water flow, which prevents the residual heat inside the casting from increasing the 7AaJX on the surface of the stone casting and causing quality problems. can be prevented.

Third Embodiment FIGS. 5 and 6 show a third embodiment of the present invention. In each of the embodiments described above, one temperature sensor was disposed between each casting, but in this embodiment, one temperature sensor is disposed in each of the vertical directions. That is, the cooling water temperature between each casting is measured at the upper and lower parts, and furthermore, the cooling rate of each casting is reduced to be uneven due to variations in the cooling water temperature.

Temperature sensors 4j4a and 4b, 5a and 5b, 6a and 6b,
7a and 7b are arranged so as to pass through the gap on the bottom of the heat treatment tray 2 when the heat treatment tray 2 descends, and when the heat treatment tray 2 is lowered, each casting 3a, 3
It is arranged to measure the water temperature between castings 3a and 3c and outside the outermost castings 3a and 3c. Temperature sensor 4a
and 4b, 5a and 5b, 6a and 6b, 7a and 7b are temperature input terminals 21a, 21b, 22 of the control means 29.
a , 22b , 23a , 23b . 24a,
24b are connected to each other, and the temperature measurement results of the respective temperature sensors are inputted to this control means 29.

For example, in the state shown in FIG. 5, the temperature sensor 14a and the temperature sensor 4b are paired, and both are located between one side surface 2a of the heat treatment tray 2 and the casting 3a. The temperature sensor g4a detects the water temperature near the top of the casting 3a, and the temperature sensor 4b detects the water temperature near the bottom of the casting 3a.

Similarly, temperature sensors 5a, 5b.
Warm fu sen +3 6a, 6b Kata a sen +J7a, 7
b are located in pairs and perform the same function as above.

Control motors 13, 15, 17, 1 that control the valve opening of each flow control valve 12, 14, 16, 18
9 are valve control signal terminals 25, 26 of the control means 29;
27, 28, and controls the valve distance of each flow rate control valve 12, 14, 16, 18 according to the valve 1 opening output signal calculated by the control means 29 based on the temperature measurement result of the temperature sensor. control and control the spray water suspension from the spray nozzle.

FIG. 6 shows a flowchart showing the procedure of the brightening method within the control means 29. Heat Treatment] Before the ray 2 starts descending into the water tank 1, a start signal is issued in step 230 in anticipation of the time until the amount of water in the circulation bomb 20 stabilizes, and the process proceeds to step 231. In step 231, the full flow suspension control valves 12, 14, 16,
A control signal is outputted to set the opening degree of 18 to 1 to the initial value, and in step 232, the circulation pump 20 is operated. Paired temperature sensors 1 4a and 4b, 5a and 5b, 6a and 6b, 7a and 7b (7) Temperature measurement results T4 and 1-
4bsTsa and T5bXT68 and a To b, T7; Input 3 and T7b, first step 2
33, the temperature measurement result Tia is determined as the spray stop temperature "st"
If it is smaller, proceed to step 234 and minimize the opening degree of the valve 12, and if it is larger, proceed to step 235 and set l Ta a Ta bl to -V limit temperature difference KU.
Compare with. Result 11-4a in step 235
If Tab1 is larger than the upper limit temperature difference KIJ, the process proceeds to step 236, where the opening degree of the valve 12 is heard by one step, and if it is smaller, the process proceeds to step 237, where lT4 and T4b1 are compared with the lower limit temperature difference K,. Result I in step 237
If Ta a T4 bI is smaller than the lower limit temperature difference K[, proceed to step 238 and close the opening degree of the valve 12 by one step;
Compare the spray stop temperature T, 1o, and a.

Thereafter, similar processing (step 240 to step 246) is performed, and each temperature measurement result T 4 a 1- is obtained at the end of each cycle.
s, T8, and Ttl are all spray stop temperatures a
a Compare whether it is smaller than Tstop in step 2I17,
If it is smaller, the pump 20 is stopped in step 248, and if not, the temperature measurement results of the temperature sensors 4a and 4b, 5a and 5b, 6a and 5b, and 7a and 7b are input again.
Repeat the same process. The lower limit temperature difference KE is to prevent the pump from wasting operating energy due to too much water being sprayed.The water volume of the pump is reduced so that there is a slight temperature difference within a range that does not cause quality problems. The purpose is to save energy.

In this example, regardless of the size of the temperature difference between the two paired temperature sensors, the valve opening is controlled by opening and closing one step at a time, and the time required for one cycle is extremely short. Therefore, the opening degree quickly becomes appropriate and there is no problem in practical use. It is advantageous to open and close the valve because the appropriate valve opening degree can be obtained more quickly.

In addition, the temperature measurement result TaB (rsB, Te
, T7 is smaller than the cooling stop temperature 1-stop, and if it is smaller, the pump 20 is stopped.The reason why the pump 20 is stopped is because it is controlled by a timer. To prevent energy loss due to continued operation of the temperature measurement result Ta as Ts a sIF B , TV
The reason why only B is used is because the water temperature is usually higher in the upper part. In addition, the temperature measurement results T4a, T-s B , Te
Compare whether each of a% T7 B is smaller than the cooling stop temperature "stop", and if it is smaller, the valve opening should not be fully opened, but should be set to the minimum opening because the temperature on the surface of the casting due to residual heat inside the casting. This is to ensure the minimum amount of water flow to prevent it from rising.

As in this example, by distributing temperature sensors between each casting at intervals in the vertical direction, the temperature of the quenching water at the top and bottom of the casting can be made almost equal, and the cooling rate at the top and bottom of the casting is uniform. This makes it possible to harden aluminum castings with less warping and distortion.

Fourth example FIG. 7 shows a fourth embodiment of the invention.

In each of the embodiments described above, each spray nozzle is connected to a flow rate control valve, and the opening degree of each flow rate control valve is controlled based on the signal from each temperature sensor, thereby controlling the ejection from each spray nozzle. Although the amount is made variable, in this embodiment, two temperature sensors and one borrow control valve are used to realize the same function as above.

As shown in FIG. 7, the temperature sensors 4a and 4b are placed at the highest temperature in the heat treatment tray 2. In this embodiment, the highest temperature is between the castings 3a and 3b in the heat treatment tray 2. This is a high temperature part.Each spray nozzle 8
, 9, 10, 11 are fixed throttle valves 8a, 9a, 1
It is connected to the flow control valve 14 via 0a and lla. The flow rate of each of the fixed throttle valves 8a to 11a is adjusted according to the water temperature distribution within the heat treatment tray 2, which is measured in advance. Therefore, this embodiment also provides effects similar to those of the embodiments described above.

Incidentally, in each of the above embodiments, a case where the present invention is applied to hardening of aluminum castings is shown, but the present invention is not limited to this as long as it is a casting.

[Effects of the Invention] As explained above, in the casting quenching method and device according to the present invention, the cooling water temperature between the castings in the water tank is detected during quenching, and the cooling water temperature in the water tank is adjusted based on the detected cooling water temperature. Since the flow rate of the cooling water jetted between the castings is controlled, the following effects can be obtained.

B) The amount of cooling water is increased in areas where the water temperature between the castings is high to increase the cooling capacity of that area, and the amount of cooling water is decreased in areas where the water temperature is low and easy to cool, so the water temperature near each casting is made uniform. It can be done. As a result, the cooling rate of each part of the casting becomes uniform, and the casting can be hardened with less warpage and residual distortion.

I The cooling water base is controlled based on the water temperature between the castings, so
There is no need to squirt extra cooling water into the water tank, which reduces energy loss.

9. Since the cooling water ω is controlled based on the water temperature between the castings, even if the type of casting changes, uniform cooling speed can be obtained without being affected by water drop.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an apparatus used in the method for hardening castings according to the first embodiment of the present invention, Fig. 2 is a flowchart showing the control flow in the apparatus of Fig. 1, and Fig. 3 is a flow chart of the present invention. FIG. 4 is a flowchart showing a modification of FIG. 3, and FIG. 5 is a flowchart showing a modification of FIG. 3, and FIG. FIG. 6 is a flowchart showing the flow of control for the device in FIG. 5; FIG. 7 is a fourth embodiment of the present invention. Fig. 8 is a schematic diagram of the apparatus used in the method for quenching castings related to the conventional method for quenching castings. ...Heat treatment trays 3a, 3b, 3c... Castings 4, 5, 6, 7
...Temperature sensor 1-4a, 4b, 5a . 5
b, 6a, 6b, 7a, 7b... Warm Sen 1 No. 8, 9, 10, 11... Spray nozzle 12
, 14, 16, 18...Flow rate control valve 20.
...Circulation pump 29...Control means Fig. 4

Claims (1)

[Claims] 1. A plurality of heated castings are immersed in cooling water in a water tank,
In the method of cooling the plurality of castings by cooling water spouted into the water tank and quenching the castings, detecting the temperature of the cooling water between the castings in the water tank during the quenching, and adjusting the temperature of the cooling water to the detected cooling water temperature. A method for quenching a casting, characterized in that the flow rate of cooling water jetted between the castings in a water tank is controlled based on the following. 2. A water tank in which the heated casting is immersed; a spray nozzle disposed in the water tank that spouts cooling water into the water tank; and a circulation pump connected to the spray nozzle that circulates the cooling water in the water tank. , a flow control pulp connected to the spray nozzle; a temperature sensor arranged in the water tank to detect the temperature of the cooling water in the water tank; and an opening degree of the flow control valve based on a signal from the temperature sensor. A casting quenching apparatus characterized by comprising: a control means for controlling;