JPH0138581B2 - - Google Patents

Description

Claim 1: Prepare core sand, make a sample from the core sand to determine the hardening time of the core sand, pack the core sand into a core box and compress it, hold the core sand in the core box, and remove the core sand from the core box. In the core manufacturing method in which the lifted core is pulled out, the hardening time of the core sand 7 is determined by the conductivity before and after hardening of the core sand and the range of change in the conductivity. While the core sand is being held, the core sand is held until the conductivity reaches a range of change in conductivity that corresponds to the core hardness that provides a core with the desired strength, and then the core is pulled out from the core box 3. Core manufacturing method consisting of

2. In the method set forth in claim 1, when the range of change in the conductivity of the core sand is within 15%,
A core manufacturing method comprising pulling the core out of a core box.

3 A core box placed on a lift table mechanically connected to the bed and filled with core sand, a temperature detection device for the core box mounted on the wall of the core box, and a core box mounted on the bed and filled with core sand. a core box separating device mechanically coupled to the core box; and a control unit connected to the mechanism and separating device, the control unit 3
0 and the core box separation device 9, and a detection device 13 for the electrophysical parameters of the core sand arranged in a groove formed in the wall of the core box 3. The device includes electrodes 15, 120 in contact with the core sand 7.
and is connected to the measurement logic unit 29.

4. The core manufacturing device according to claim 3, wherein the measurement logic unit 29 comprises a trigger unit 31, a unit 32 for the initial measurement of electrophysical parameters of the core sand, a cycle control unit 33, a core Comparison of the electrophysical parameters of the core sand connected to a unit 34 for repeated measurements of the electrophysical parameters of the sand and a unit 32 for initial measurements of the electrophysical parameters of the core sand and to a cycle control unit 33 vessel 35
and an operating mode connected to a trigger unit 31, a unit 32 for the initial measurement of the electrophysical parameters of the core sand, a cycle control unit 33 and a unit 34 for the repeated measurement of the electrophysical parameters of the core sand. Selection switch 36
, an output signal amplifier 37 and a unit 3 for repeatedly measuring the electrophysical parameters of the core sand.
A core manufacturing device comprising 4.

5. In the apparatus according to claim 4, the input end of the trigger unit 31 is the input end of the trigger unit 31, and the trigger unit 31 has an input end that is connected to the core sand electrophysical parameter detection device 13, the status display device 44, and the A threshold element 43 connected to inputs 45, 47 of gate 46, and a flip-flop 4 connected with one input to input 40 of trigger unit 31 and the other input 48 of AND gate 46.
9 and a single pulse shaping circuit 52 connected to the input terminal 51 of the AND gate 46.

6. In the device according to claim 4, the unit 32 for the initial measurement of the electrophysical parameters of the core sand has an input terminal 56 connected to the output terminal of the single pulse shaping circuit 52 of the trigger unit 31. an OR gate 53 whose input terminal 57 is connected to the operation mode selection switch 36; a flip-flop 54 whose input terminal 55 is connected to the OR gate 53; and one input terminal 64 connected to the output terminal 62 of the flip-flop 54.
and the other input terminal is the input terminal of the unit 32 for the initial measurement of the electrophysical parameters of the core sand and is connected to the AND gate 63 which is connected to the pulse oscillator 38, and one input terminal 70 is connected to the AND gate 63. and the other input terminal 66 is connected to the flip-flop 54.
a variable countdown ratio counter 65 connected to the output terminal 68 of the variable countdown ratio counter 65; a switch device 72 connected to the other input terminal 71 of the variable countdown ratio counter 65; one input terminal 75 connected to the variable countdown ratio counter 65; A pulse counter 73 having an input 74 connected to the OR gate 53, a sawtooth voltage generator 61 having inputs 67 and 69 connected respectively to outputs 68 and 62 of the flip-flop 54, and one input 41 connected to the core sand. The input end of the unit 32 for the initial measurement of the electrophysical parameters of the core sand is connected to the detection device 13 for electrophysical parameters, and the other input end 60 is connected to the sawtooth voltage generator 61, and the output end is and a voltage comparator 59 connected to the other input terminal 58 of the flip-flop 54.

7. The device according to claim 4, wherein the cycle control unit 33 comprises an OR gate 76 having an input 79 connected to a voltage comparator 59 of the unit 32 for the initial measurement of the electrophysical parameters of the core sand. , a flip-flop 77 whose input terminal 78 is connected to the OR gate 76, an AND gate 83 which serves as an input terminal of the cycle control unit 33 having one input terminal connected to the flip-flop 77 and the other input terminal connected to the pulse oscillator 38; a time counter 84 with its end 85 connected to an AND gate 83 and two main decoders 87, 8 with their respective inputs 90, 91, 92 each connected to two single pulse shaping circuits 93 as well as a time counter 84;
8 and an auxiliary decoder 89.

8. In the device according to claim 4, the unit 34 for repeatedly measuring the electrophysical parameters of the core sand comprises a flip-flop 94 whose input terminal 95 is connected to the auxiliary decoder 89 of the cycle control unit 33; The input terminals 101 and 102 are connected to the output terminals 97 and 103, respectively.
a sawtooth voltage generator connected to one input end 9
9 is connected to an input 97 of a flip-flop 94 and a unit 34 for repeatedly measuring electrophysical parameters of the core sand is connected to a pulse oscillator 38.
and an AND gate 98 with the other input terminal as an input terminal, and one input terminal 105 connected to a sawtooth voltage generator to detect the electrophysical parameters of the core sand. a voltage comparator 104 whose other input is used as an input of the unit 34 for repeated measurements.

9. In the device according to claim 4, the comparator 35 of the electrophysical parameters of the core sand of the measurement logic unit 29 is a reversible counter, one input of which is used to measure the electrophysical parameters of the core sand. It is connected to the AND gate 98 of the unit 34 for repeated measurements, and the other two inputs are connected to the single pulse shaping circuit 93 of the cycle control unit 33.
and a data input terminal is connected to a pulse counter 34 of a unit 32 for initial measurements of electrophysical parameters of the core sand.

10 In the device according to claim 4, the operation mode selection switch 36 includes three switch devices 106, 107, 108 and a trigger unit 31.
and an AND gate 109 having one of its input terminals connected to the AND gate 46 and its output terminal connected to the input terminal of a third switch device 108. Unit 34 for repeatedly measuring physical parameters
The second switching device 107 has one of its inputs connected to the output of the reversible counter, and the second switching device 107 has one of its inputs connected to the output of the reversible counter.
6 input terminal 112 and second switch device 107
The inputs 113 of are connected to each other at point 111 and to the input 110 of the AND gate 109 and to the input 96 of a flip-flop 94 of the unit 34 for repeated measurements of the electrophysical parameters of the core sand. 2 switch devices 106, 10
The remaining outputs 114, 115 of the third switching device 108 are connected to each other at point 116 and to the output signal amplifier 37 as well as to the other input 50 of the flip-flop 49 of the trigger unit 31, and to the outputs 117, 115 of the third switching device 108. 118 is a core manufacturing device connected to the unit 32 for initial measurement of electrophysical parameters of the core sand and to the input ends 57, 80 of the OR gates 53, 76 of the cycle control unit 33;

11. In the apparatus according to claim 3, one of the apparatuses 13 for detecting electrophysical parameters of core sand.
A core manufacturing device in which two electrodes 15 are coupled to a main body 14 and rotatably mounted thereon.

12. The device according to claim 11,
A core manufacturing device in which rotation of the electrode 15 is achieved by a pair of screws formed in the main body 14 and the electrode 15.

13. A core manufacturing apparatus according to claim 11 or 12, wherein the second electrode is located on the inner surface of the core box 3 and is in contact with the core sand 7.

14. The device according to claim 11,
Device for detecting electrophysical parameters of core sand 13
further includes a dielectric sleeve 11 placed on the electrode 15, in contact with the core sand 7, and containing a second electrode 120;
9, the body of the first electrode 15 is connected to the second electrode 1
Wire 2 connecting 20 to measurement logic unit 29
6. A core manufacturing device having a groove for routing a core.

15. The device according to claim 14,
The second electrode 120 and dielectric sleeve 119 are 4
The core manufacturing device has a tapered shape having an angle of ~8 degrees, with the wider bottom surface facing the first electrode 15.

16. The device according to claim 11,
The second electrode is in the form of a ring 121 and the dielectric plug 20 from which the first electrode 15 extends is in the form of a ring 1
A core manufacturing device having an annular groove corresponding to No. 21.

17. A core manufacturing apparatus according to claim 3, wherein the core sand electrophysical parameter detection device 13 is rotatably mounted.

18. The device according to claim 17,
Device for detecting electrophysical parameters of core sand 13
is rotatable by means of a sleeve 123 and a pair of screws formed on the surface of a groove housing the sleeve 123, and the sleeve 123 is coupled to the core box separation device 9 and a detection device 13 for electrophysical parameters of the core sand. A core manufacturing device configured to be housed in a main body 14 of.

TECHNICAL FIELD The present invention relates to casting technology, and particularly to a method and apparatus for manufacturing a core.

Background of the Technology To efficiently manufacture hot box cores and cores from self-hardening sand, it is extremely important to accurately measure the hardening time of the core. The optimum value of the core curing time depends on the physical and mechanical properties of the core sand and the reactivity of the binder. Because of this, curing times vary considerably.

On the other hand, it is common to determine the optimum value of the core curing time prior to sampling. However, this requires a lot of time and effort, and the hardening time of the core must not be changed even if the parameters of the core sand are changed.

This kind of core manufacturing method is called "Machines and
Automation in Foundry Practice” (Russian)
“Vysheishaya Shkola” by IB Zaigerov,
Minsk, 1969, pages 273-274. According to this manufacturing method, a core sand is used as a reference, a sample for determining the hardening time of the core sand is made from the core sand, a core box is filled with the core sand, and the core sand is packed and hardened in the core box. Remove the hardened core from the core box. The curing time of the core is determined during sampling.

In addition, the equipment for carrying out this type of core manufacturing method is "Machines and Automation in
"Foundry Practice" (Russian) IB, Zaigerov
Author, "Vysheishaya Shkola", Minsk, 1969,
It is described on pages 259-268. This device includes a core box provided on a lift table mechanically connected to the bed, a core box temperature transmitter placed inside the core box, and a core box fixed to the bed for filling and packing the core sand. a core box opening device mechanically coupled to the core box; a control unit connected to a device for filling and packing the core box with core sand and to the core box opening device.

However, the core manufacturing method and apparatus described above leaves the core curing time substantially unchanged despite changes in the reactivity of the binder and changes in the physico-mechanical properties of the core sand. For this reason, the core may be taken out prematurely or may be left in the core box longer than necessary. This, on the contrary, makes it impossible to obtain a core of a given strength,
It also affects the efficiency of core manufacturing equipment.

Furthermore, according to the above-mentioned core manufacturing method and apparatus,
If the core curing time is prolonged, the binder will partially deteriorate. This increases the consumption of binder and electric power, and also increases the consumption of gas catalyst if used in the manufacture of the core.

[Detailed description of the invention]

The object of the present invention is to provide a method for manufacturing a core that can obtain a core of a desired strength, including a technique for determining the hardening time of core sand, and to increase the efficiency of manufacturing the core that can obtain a core of a desired strength. It is an object of the present invention to obtain a core manufacturing apparatus for carrying out the aforementioned manufacturing method, which has an auxiliary unit capable of performing the above-described manufacturing method.

To achieve this objective, according to the core manufacturing method of the present invention, core sand is prepared, a sample is made from the core sand to determine the hardening time of the core sand, a core box is filled with the core sand, and the core sand is placed in the core box. In the method of holding core sand in a core box and pulling out the core from a core box, the hardening time of the core sand is determined by measuring the conductivity of the sample before and after hardening, and at the same time by measuring the range of change in conductivity. In addition, the sample is held in the core box until the conductivity falls within the range of change, and after confirming that the strength of the sample has reached the desired core strength by entering the range of change, the core is placed in the core box. Make sure to pull it out.

It is desirable that the core be pulled out when the conductivity of the core sand falls within the range of 15% in the range of change.

Further, in order to achieve the object of the present invention, a core manufacturing apparatus for carrying out the above-mentioned method includes a core box temperature transmitter provided on a lift table mechanically coupled to the bed, and a core sand in the core box. a mechanical device fixed to the bed for filling and packing the core sand; a core box separation device mechanically coupled to the core box; a device for filling and packing the core box with core sand; and a mechanical device for the core box separation device. a measuring logic unit electrically connected to said control unit and to a separating device of the core box; and an apparatus for detecting electrophysical parameters of the core sand, each having an electrode connected to the unit.

The measurement logic unit includes, for example, a trigger unit, a unit for initial measurements of the electrophysical parameters of the core sand, a cycle control unit, a unit for repeated measurements of the electrophysical parameters of the core sand, and a unit for the repeated measurement of the electrophysical parameters of the core sand. a comparator and a trigger unit for the electrophysical parameters of the core sand connected to the unit for making the initial measurements of the electrophysical parameters of the core sand and the cycle control unit; an operating mode selection switch connected respectively to the unit, the cycle control unit and the unit for repeated measurements of the electrophysical parameters of the core sand, and an output signal amplifier and for the initial measurement of the electrophysical parameters of the core sand. unit, a cycle control unit and a pulse oscillator connected to the unit for repeatedly measuring the electrophysical parameters of the core sand.

The trigger unit is, for example, one of these units.
a threshold element having two inputs and connected to a detection device for electrophysical parameters of the core sand; a status display device and an AND gate each having an input end connected to the threshold element; and another input end of the AND gate. and a flip-flop connected to the control unit and having one input as the input of the trigger unit, and a single pulse shaping circuit connected to the output of the AND gate.

The unit for carrying out initial measurements of the electrophysical parameters of the core sand can, for example, be connected at one input to the output of a single pulse shaping circuit of a trigger unit and at the other to an operating mode selection switch. an OR gate, a flip-flop with one input connected to this OR gate, one of its inputs connected to one of the inputs of the flip-flop, and the other input connected to an initial measurement of the electrophysical parameters of the core sand; a variable countdown ratio counter with one of its inputs connected to the AND gate and the other to the other output of the flip-flop; a switching device connected to the input end of the
A pulse counter with one input connected to a variable countdown ratio counter and the other input connected to an OR gate, a sawtooth voltage generator with its input connected to the output of a flip-flop, and one input connected to a core sand. The input end of the unit for the initial measurement of the electrophysical properties of the core sand is connected to a voltage comparator whose input end is connected to a detection device for the electrophysical parameters of the core sand and whose output end is connected to the other end of the flip-flop. Make sure you have it.

The cycle control unit has, for example, an OR gate connected to one of its inputs to a voltage comparator of the unit for the initial measurement of the electrophysical parameters of the core sand, and one of its inputs connected to this OR gate. A flip-flop, an AND gate with one of its inputs connected to the flip-flop and the other input of the cycle control unit connected to a pulse generator, and a time gate with one of its inputs connected to the AND gate. A counter, two main and auxiliary decoders having their inputs connected to the time counter, and two single pulse shaping circuits respectively connected to each main decoder.

A unit for repeatedly measuring the electrophysical parameters of the core sand, which is part of the measurement logic unit, can be constructed, for example, by a flip-flop with one of its inputs connected to the auxiliary decoder of the cycle control unit, and each flip-flop of this flip-flop. a sawtooth voltage generator, each with an input connected to the output, and one of the inputs connected to one of the outputs of a flip-flop, the other input for repeated measurements of the electrophysical parameters of the core sand. An AND gate connected to the pulse generator as the input of the unit, one of the inputs connected to the sawtooth voltage generator and the other input of the unit for repeatedly measuring the electrophysical parameters of the core sand. and a voltage comparator connected as an input to a device for detecting electrophysical parameters of the core sand.

The comparator for the electrophysical parameters of the core sand is, for example, a reversible counter, one of whose inputs is connected to the AND gate of the unit for repeated measurement of the electrophysical parameters of the core sand, and the other two.
The two inputs are connected to the single pulse shaping circuit of the cycle control unit and the data input is connected to the pulse counter of the unit for initial measurements of electrophysical parameters of the core sand.

The operating mode selection switch consists, for example, of three switching devices and an AND gate with one of its inputs connected to the AND gate of the trigger unit, the first switching device repeatedly measuring the electrophysical parameters of the core sand. A second switching device has one of its inputs connected to the output of the reversible counter and its output connected to the input of the other switching device. , one output end of one switching device and one output end of the other switching device are interconnected to the other input end of the AND gate and a unit for repeatedly measuring the electrophysical parameters of the core sand. The remaining output ends of the two switching devices are connected to each other and to the other end of the flip-flop of the output signal amplifier and trigger unit, and the third switching device is connected to the other input end of the flip-flop of the third switching device. The output end is connected to the input end of each OR gate of the unit for initial measurement of the electrophysical parameters of the core sand and of the cycle control unit.

The detection device of electrophysical parameters of core sand is
For example, with a replaceable electrode connected to the core sand. The electrodes are exchangeably combined by screws formed on both the detection device and the electrodes.
The other electrodes are placed on the inner surface of the core box in contact with the core sand.

The detection device of electrophysical parameters of core sand is
For example, it may include a dielectric sleeve placed over the end of the first electrode. This sleeve is in contact with the core sand and houses a second electrode. The first electrode body has a duct-like groove through which wires connecting to the second electrode and the measurement logic unit are routed.

The second electrode and the dielectric sleeve are, for example, 4° to
It is tapered at an angle of 8°, with the larger bottom facing the first electrode.

In some cases, the second electrode may be ring-shaped, and in this case, the dielectric plug through which the first electrode is routed forms an annular groove corresponding to the ring.

The device for detecting the electrophysical parameters of the core sand is installed to be replaceable.

This detection device is connected to the core box separation device and is exchangeably assembled by threading both the sleeve containing the detection object and the duct surface containing this sleeve.

According to the present invention, it is possible to determine a practical optimum curing time for each core, and thus a core of desired strength can be obtained.

Further, according to the present invention, the core manufacturing time can be shortened and the manufacturing capacity of the core manufacturing apparatus can be increased.

Furthermore, according to the present invention, the amount of binder in the core sand can be reduced, the amount of gas catalyst can be reduced, and the properties of the core sand can be used more efficiently.

Embodiments of the Invention According to the core manufacturing method of the present invention, firstly, core sand is prepared, and secondly, a sample for determining the hardening time of the core sand is prepared, and the conductivity of the sample before and after hardening is determined. Manufacture by measuring. At the same time, determine the width of the conductivity change. The conductivity is measured while the prepared core sand is introduced into the core box, packed and retained within the core box. When the conductivity value is high enough to indicate the desired hardness corresponding to the strength of the resulting core, the manufacturing process is stopped and the core is removed from the core box.

The heat retention capacity of the core is first determined by the mass of the core, so a large core with a mass of 14 to 16 kg has a large heat retention capacity, and the conductivity changes with the range of change.
When it reaches 15%, remove it from the core box. That is, in this case, it is better to stop the hardening process of the core sand while the hardness of the binder is low, and the hardening of the core should be completed outside the core box because the heat is retained in the core. do.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings and FIG.

FIG. 1 shows a bed 1 and a lift table 2 placed on the bed. A core box 3 consisting of two parts 4, 5 is arranged on the lift table 2. Inside this core box 3, a base body 8 of a core box separation device 9 is fixed to the lift table 2 by a mechanism 6 (hereinafter referred to as the supply compression mechanism 6) fixed to the vertical part of the bed 1, and its cylindrical shape It is supported on the base body 8 with a portion 10. The cylindrical part 10 has a rod 11 fixed to the part 5 of the core box 3.
has. A core box temperature sensor 12 connected to a temperature regulator (not shown) is mounted in this part 5. The part 4 of the core box 3 is provided with a groove for housing a device 13 for detecting electrophysical parameters of the core sand.

The detection device 13 includes a main body 14 (FIGS. 1 and 2) that houses an electrode 15 fixed in a dielectric plug 16.
). The plug 16 is assembled to the main body 14 by a threaded groove 17. The plug 16 is connected to the electrode 1 by a nut 18 and a washer 19.
5 is retained. A heat-resistant dielectric plug 20 in contact with the core sand 7 is fixed to one end of the body 14, and an electrode 15 extends through this plug. A slot 21 is formed at one end of the electrode 15 in the main body 14, so that the electrode can be replaced. A metal plug 22 is fixed to the other end of the main body 14. Further, the main body 14 has a branch pipe 23, and an insulator 25 for drawing out the wire is fixed to this pipe 23 with a hexagonal nut 24. A wire 26 extends from the insulator 25 and is connected to the electrode 15 by a nut 18 and a washer 19.

This detection device 13 is firmly fixed to a body 14 having a threaded portion 28 receiving a hexagonal nut 27. The core box 3 acts as a second electrode and its inner surface is in contact with the core sand 7. The core box 3 is also connected to the measurement logic unit 29 by other wires (not shown). unit 2
9 is electrically connected to the detection device 13 and the mechanism 6. Mechanism 6, lift table 2, and unit 2
9 is electrically connected to the control unit 30.

The measurement logic unit 29 is connected to the trigger unit 31
(FIG. 3), a unit 32 for the initial measurement of the electrophysical parameters of the core sand, a cycle control unit 33, a unit 34 for the repeated measurement of the electrophysical parameters of the core sand, a unit 34 for the repeated measurement of the electrophysical parameters of the core sand. It consists of a parameter comparator 35, an operation mode switch 36, and an output signal amplifier 37 connected in cascade. Units 32, 33, 34 are connected to a pulse generator 38. The unit 31 is connected to a switching device 36, a second input 29 is connected to a detection device 13, and a third input 40
is connected to unit 30. unit 32
is connected to the unit 35 and the switch device 36, and its input end 41 is connected to the detection device 13. Unit 33 is connected to unit 35 and switch device 36. The unit 34 is connected to a switch device 36 and its input 42 is connected to the detection device 13.

Trigger unit 31 includes threshold element 43 (FIG. 4)
The input terminal 45 is a status display device 4.
4 and an input terminal 47 of an AND gate 46. A second input 48 of AND gate 46 is connected to a flip-flop 49, and an input 50 of flip-flop 49 is connected to switch device 36. An output terminal 51 of the AND gate 46 is connected to a single pulse shaping circuit 52.

The unit 32 for the initial measurement of the electrophysical parameters of the core sand is an or gate 53 (FIG. 5).
The OR gate 53 is connected to the input terminal 55 of the flip-flop 54. The input terminals 56 and 57 of the OR gate 53 are connected to a single pulse shaping circuit 52 (FIG. 4) and a switching device 36, respectively.
(Fig. 3). The other input 58 (FIG. 5) of flip-flop 54 is connected to voltage comparator 5.
9 , and the input 60 of the comparator 59 is connected to a sawtooth voltage generator 61 . The output terminal 62 of the flip-flop 54 is an AND gate 63.
is connected to the input terminal 64 of. An input 66 of the variable countdown ratio counter 65 and an input 67 of the voltage generator 61 are connected to the other output 69 of the flip-flop 54. The other input 68 of the voltage generator 61 is connected to the output 62 of the flip-flop 54. AND gate 63 is connected to an input 70 of counter 65, and its input 71 is connected to switch device 72.
OR gate 53 and counter 65 are connected to input terminals 74 and 75 of pulse counter 73, respectively.

The cycle control unit 33 has an OR gate 76
(FIG. 6) and is connected to the input terminal 78 of the flip-flop 77. Inputs 79, 80 of OR gate 76 are connected to comparator 59 (FIG. 5) and switch device 36 (FIG. 3), respectively. The other input 81 (FIG. 6) of flip-flop 77 is connected to unit 34 (FIG. 3). Input terminal 82 of flip-flop 77 (sixth
) is connected to an AND gate 83. AND gate 83 is input terminal 85 of time counter 84
The input terminal 86 of the time counter 84 is connected to the unit 34 (FIG. 3). The time counter 84 (FIG. 5) is connected to the input terminals 90 of the main decoders 87, 88 and the auxiliary decoder 89,
91 and 92, respectively. Decoders 87 and 88 are connected to a single pulse shaping circuit 93.

The unit 34 for repeatedly measuring the electrophysical parameters of the core sand is a flip-flop 94.
(Fig. 7), flip-flop 94
The input terminals 95, 96 of are connected to the decoder 89 (FIG. 6) and the switch device 36 (FIG. 3), respectively. Output terminal 97 of flip-flop 94
(FIG. 7) is connected to the input 99 of the AND gate 98 and the input 101 of the sawtooth voltage generator 100. Input 102 of voltage generator 100 is connected to input 103 of flip-flop 94. Voltage generator 100 is connected to input 105 of voltage generator 104 .

The operating mode selection switch 36 includes three switch devices 106, 107, and 108 (FIG. 8). Device 108 is connected to an AND gate 109, whose input 110 is connected to point 111. At this point 111 the outputs 112, 113 of the devices 106, 107 are interconnected, respectively. Output end 114,1 of device 106,107
15 are connected at a point 116, which is connected to the input terminal 50 of the flip-flop 49.
(FIG. 4) and an output signal amplifier 37 (FIG. 5). Output 117,1 of device 108
18 is connected to the input terminal 80 of the OR gate 76 (FIG. 6) and the input terminal 57 of the OR gate 53 (FIG. 5).

According to another embodiment of the invention, a device 13 for detecting electrophysical parameters of core sand of a core manufacturing device
(FIG. 9) further includes a dielectric sleeve 119. This sleeve 119 is supported within the electrode 15, houses the second electrode 120, and is in contact with the core sand 7. Wire 2 passing through the duct of electrode 15
6 is connected to the electrode 120. The electrodes 15 are electrically connected to the body 14 which is connected by other wires (not shown) to the measurement logic unit 29. Electrode 120 and dielectric sleeve 119
has a tapered shape forming an angle of 4° to 5°, and its wide bottom face faces the electrode 15.

According to another embodiment of the present invention, in a core manufacturing apparatus for carrying out the method according to the present invention, the device 13 for detecting electrophysical parameters of core sand has the shape of a ring 121 (FIG. 10). The plug 20 is molded to fit within an annular groove provided within the plug 20. The ring 121 is connected to the wire 122 (first
0) to unit 29 (FIG. 1).

According to a further embodiment of the invention, the core manufacturing device comprises a sleeve 123 (FIG. 11) housed in the body 14 of the detection device 13.

The operation of the core manufacturing apparatus is as follows.

The conductivity of a core sand containing a non-conductive solid component (e.g. silica sand) and a conductive material used as a binder depends on the binder content in the core sand, the uniformity of the binder distribution on the silica sand grain surface, the core sand is determined by variable parameters such as the degree of compression.

When the core sand is heated, the conductivity initially increases due to the increased displacement of the ions. The binder then begins to harden, but at this stage the conductivity begins to decrease.

The conductivity of the core sand is maximized by using binder,
Also, when the core strength is maximized,
Minimum. When the core is held at high temperatures, the binder deteriorates and the conductivity increases. however,
If the core is pulled out of the core box when the electrical conductivity is at its minimum, the strength of the core will not be maximized. This is because after the core is pulled out from the core box, the heat retained by the core causes curing to occur later. However, since it is outside the core box, this degrades the binder.

Based on commands given by the control unit 30 (FIG. 1), the preheated core box 3 is filled with core sand 7 by the supply compression mechanism 6. The temperature of the core box is controlled by a temperature detector 12 and a temperature regulator (not shown). The core sand 7 in the core box 3 is in electrical contact with the inner surface of the core box 3 and with the electrodes 15 of the device 13 for detecting electrophysical parameters of the core sand. Unit 30 provides commands to drive measurement logic unit 29. By means of the signals from the detection device 13, the measuring logic unit 29 monitors the degree of hardening of the core sand 7, ie the core sand becomes a core.

When the core reaches a predetermined hardness, i.e. when the conductivity reaches a preset value, the unit 29 commands the core box separation mechanism 9 to separate the parts 4, 5 of the core box 3.

The finished core is withdrawn from the core box 3 and a command issued by the unit 30 causes the core manufacturing apparatus to return to its initial position in preparation for the next cycle.

Measurement logic unit 29 operates as follows.

Signals from the control unit 30 (FIGS. 1 and 3) cause the trigger unit 31 to activate the unit 3 for initial measurements of the electrophysical parameters of the core sand.
2, give a single pulse. This allows the detection device 13 to be connected to the input terminal 39 of the trigger unit 31.
is given a signal with a value greater than the current value. Because the conductivity of core sand is the evaluation standard for core quality,
It is possible to avoid producing cores from poor quality core sand (eg dry, low binder content, etc.). In this way, the quality of the core sand 7 is strictly controlled.

The trigger pulse causes the unit 32 to start measuring the electrophysical parameters of the core sand 7, and according to the predetermined range of change in the conductivity of the core sand 7 as well as the heat retention properties of the core, the unit 32 starts measuring the electrophysical parameters of the core sand 7. The measured value of the signal applied from the device 13 to the input terminal 41 is converted.

The obtained data are stored by unit 32 and a signal is given to cycle control unit 33 indicating that one measurement cycle has been completed. After a predetermined time, the unit 33 sends two signals to the electrophysical parameter comparator 35. One of the signals resets unit 35 and the other stores the converted data available at the output of unit 32. Unit 33 sends out signals that drive unit 34 for repeated measurements of electrophysical parameters of the core sand. Unit 34 connects the output of voltage generator 38 to the input of unit 35 for a time proportional to the signal value applied by detection device 13 to input 42 of unit 34. When unit 34 starts operating, unit 3
The unit 33 is reset by the signal No. 4. The unit 35 stores the core sand 7 stored in its memory.
The measured values of the electrophysical parameters of the unit 34 are
Compare with the measured data. The core manufacturing apparatus is operated by switch 36 in two modes.

To prevent deterioration of the binder, the core must be withdrawn from the core box before the conductivity reaches a minimum, so that the heat retained by the core causes the binder to subsequently harden outside the core box 3.

The electrical conductivity when the core is to be drawn out from the core box 3 falls within the range of change in the electrical conductivity of the core sand 7 before and after the core sand is completely hardened. The initial conductivity change of the core sand 7 causes the final conductivity change. The range of change in conductivity for a given material and for a given core sand 7 is constant.

Further, the range of change in conductivity can also be determined by the core sand in the core box. in this case,
The conductivity of the core sand 7 is measured immediately after the core sand is fed into the core box 3 and compacted. core sand 7
is retained in the core box until complete curing, i.e., minimum conductivity. The minimum conductivity value of the core sand is used to determine the range of conductivity variation. The strength of the core used to determine this range of change is less than the maximum strength that can be obtained because the binder is partially degraded by the heat retained after the core is pulled out from the core box 3. According to this invention, the core box 3 is pulled out when the conductivity reaches a certain range of change. This variation range corresponds to the hardness of the core sand at which the core reaches the desired strength.

The hardness of the core sand 7, and therefore the conductivity at which the core should be drawn out of the core box 3 for subsequent hardening outside the core box 3 to reach a certain strength, depends on the heat retention properties of the core and can be determined experimentally. determined. For this purpose, several cores are made from a group of core sands whose conductivity varies within a known range. Next, cores with several different conductivities are pulled out of the core box 3, and the physical and mechanical properties of the cores are determined using conventional methods to find a core with the desired strength. This determines the conductivity of the core sand at the time it is to be withdrawn from the core box.

Based on these conductivity values and the range of change in the conductivity of the core sand during hardening, it is possible to determine the portion of the range of change in the conductivity that allows a desired core to be obtained. The value of this change width is constant as long as the core has a predetermined shape and size, and does not change depending on the characteristics of the core sand. This is because the range of change is determined only by the heat retention properties of the core and is virtually unrelated to changes in the initial properties of the core sand 7.

According to a first mode of operation, unit 35 of measurement logic unit 29 compares the initial conductivity measurement stored in unit 32 with the measurement data of unit 34, which means that the new conductivity value is This will continue until it is accumulated.

When the compared conductivities are different from each other and when the measurement data accumulated in the unit 32 is less than the value measured by the unit 34, the unit 35
A signal is sent from the switch 36 to the switch 36. That is, in such a case, the switch 36 generates a trigger signal to drive the unit 33 and the unit 35.
It also sends a signal to reset the unit 35.
The memory contents of the unit 32 are transferred to the unit 32. Furthermore, when unit 34 is activated, unit 35 starts comparing and unit 33 is reset.

Unit 29 repeats the comparison cycle until the conductivity of core sand 7 is less than or equal to the value stored in memory 32, as measured by unit 34. In this case, a signal is applied from unit 34 to one of the inputs of switch 36,
6 generates a signal to be applied to the input terminal of the trigger unit 31 and the output signal amplifier 37. This signal resets unit 31 and amplifier 37 generates a signal to feed mechanism 9, completing the core manufacturing cycle.

The second mode of operation of unit 29 is used to produce small cores with low heat retention capacity. To implement this mode, switch 36 is set to the second position. Unit 30 to Unit 3
By means of a signal applied to input 40 of unit 31, unit 31 generates a signal which is applied to the inputs of units 32 and 36. The unit 32 measures the electrical conductivity of the core sand 7 and transmits the measured values at the same time. This measured value is proportional to the signal supplied from the detection device 13 to the input of the unit 32. Upon completing the measurement cycle, unit 32
After a predetermined time, unit 33 sends a control signal to units 34 and 35. These control signals reset unit 35 and also store the core sand conductivity data measured by unit 32. Unit 34 measures the signal value delivered by detection device 13 to input 42 of unit 34, and unit 35 compares the first and next measurement results. The signal sent from the unit 34 is applied to the input end of the switch 36 until the second measurement data by the unit 34 is less than the first measurement data stored in the unit 32, and the switch 36 transmits the signal to the unit 32. Send out. The unit 32 erases the initial data and repeats the measurement of the conductivity of the core sand 7 in proportion to the signal supplied from the detection device 13 to the input 41. Units 33, 34, 35 and switch 3
6 operates sequentially as described above and the results of two successive measurements of the conductivity of the core sand 7 are compared.

The cycle of measurement and comparison is such that when the value of the measured data at the output end of the unit 32 is less than or equal to the data value measured by the unit 34, the core sand 7 is
is repeated until the conductivity of unit 35
The comparison signal sent by is given to the switch 36,
This switch 36 connects the unit 31 and the amplifier 37.
transfer the signal to. The unit 31 is reset, the amplifier 37 sends a signal to the mechanism 9 to open the core box 3, and core production is completed.

Trigger unit 31 (Figs. 1, 3, 4)
The operation of Figure) is as follows.

After the core box 3 has been filled with core sand 7, the detection device 13 emits a signal proportional to the electrical conductivity of the core sand 7. This signal is applied to input 39 of unit 31. Here, if the signal value is greater than or equal to the preset value (the preset value indicates that there is a necessary amount of core sand 7 in the core box 3), the threshold element 43
prepares the unit 31 for operation. Threshold element 43
The status of is indicated by the display 44. Therefore,
The operator can see whether the unit 31 is ready for operation.

When a signal is supplied from the control unit 30 to the input 40 of the flip-flop 49, the flip-flop 49 is activated and at the same time a signal is sent to the input 48 of the AND gate 46. When threshold element 43 is activated, a signal is applied to input 47 of AND gate 46 . Thus, when a signal is applied to the input terminal 48 of the AND gate 46, the AND gate 46
An output appears at the output end 51 of. and gate 4
The output signal of 6 is applied to switch 36 and single pulse generator 52. A signal from the output terminal 51 of the AND gate 46 causes the shaping circuit 52 to generate a pulse to be applied to the unit 32.

The unit (FIGS. 1, 3, and 5) that performs the initial measurements of the electrophysical parameters of the core sand operates as follows.

From the shaping circuit 52 of the unit 31 to the OR gate 5
When a pulse is applied to the input 56 of the switch 3 or from the switch 36 to the input 57, the OR gate 53 sends a signal to the input 74 of the counter 73, resetting the counter 73. At the same time, ORGATE 5
3 to an input terminal 55 of a flip-flop 54. For this reason, the flip-flop 54
operates, and a “1” signal is output to the output terminal 62.
A “0” signal is generated at 9. The signal from the output terminal 62 is applied to the input terminal 64 of the AND gate 63,
Pulses are continuously supplied from a pulse generator 38 to the other input terminal. Input terminal 6 of AND gate 63
If an enable signal is present at 4, the output pulses of the pulse oscillator 38 can be fed to the input 70 of the counter 65 via the AND gate 63. The countdown ratio of the counter 65 is predetermined by a switching device 72 which performs the desired switching action at the input of the counter 65. The switch device 72 converts the electrical conductivity of the core sand 7 into a value equal to the electrical conductivity corresponding to a predetermined hardness.

In this way, the variable countdown ratio counter 65
A series of pulses is formed at the output of the counter 65 and at the input 75 of the pulse counter 73, the number of which is different from the number of pulses applied to the input 70 of the counter 65. The ratio between the number of pulses at the input end and the number of pulses at the output end of the counter 65 is determined by the state of the switch device 72. A pulse applied to the input 75 of the counter 73 activates the counter 73, the output of which represents the measurement data in terms of the total number of pulses applied to the input 75. At the same time, the counter 65 starts operating and the signal applied to its input 68 activates the sawtooth voltage generator 61. The output signal of voltage generator 61 increases directly from zero in proportion to time. This signal is applied to an input 60 of a voltage comparator 59 to which a signal proportional to the conductivity of the core sand 7 is applied from the detection device 13 to the input 41 of the comparator 59 . When the potentials of the input terminals 41 and 60 become equal, the comparator 5
9 sends out a signal to be applied to input terminal 58 of flip-flop 54 and unit 33. A signal applied to input 58 of flip-flop 54 changes the state of flip-flop 54, causing output 62 to change to "0" and output 69 to "1". Therefore, the counter 65 stops. This means that the output pulse of the pulse oscillator 38 is no longer output from the AND gate 63.
, and therefore no pulse is applied to the input terminal 75 of the counter 73 anymore. The output signal of the counter 73 is the output signal of the comparator 5.
It is the same as when 9 was started. The signal "1" at the output terminal 69 of the flip-flop 54 is applied to the input terminals 66 and 67 of the counter 65 and the generator 61, respectively.
Reset. This allows the unit 32
is now ready to repeat the measurement cycle.

Cycle control unit 33 (Fig. 1, Fig. 2,
FIG. 6) operates as follows.

A pulse applied from the output end of the comparator 59 of the gate 31 to the input end 79 of the OR gate 76, or from the output end of the switch 36 to the input end 8 of the OR gate 76.
A pulse applied to 0 drives OR gate 76. The signal from OR gate 76 is applied to input 78 of flip-flop 77, which generates a signal at output 82. The signal produced at the output 82 of flip-flop 77 is an enable signal, which allows the output pulses of pulse oscillator 38 to pass through AND gate 83. This pulse is passed through an AND gate 83 to a counter 84.
is applied to input 85 of , causing counter 84 to count the cycle time. The state of the output end of the counter 84 changes over time, and after a preset time has elapsed, the output becomes a state corresponding to the state of the input end of the decoder 87. Decoder 87 generates a signal and sends it to the input of single pulse shaping circuit 93. The single pulse shaping circuit 93 thereby generates a pulse to be applied to the input of the unit 35,
Unit 35 is reset.

Counter 84 is active and decoder 88
When that signal is applied to the input 91 of the decoder 88, the decoder 88 activates the single pulse shaping circuit 93.
The output pulse of the pulse shaping circuit 93 is sent to the unit 35.
The unit 35 stores the state of the output terminal of the unit 32 connected to the unit 35.
Counter 84 continues to operate until its output signal equals the signal at the output of decoder 89, which sends an output to unit 34. When a signal is applied from unit 34 to input 81 of flip-flop 77 and a signal applied to input 86 of counter 84, unit 33 is reset.
This signal is sent to the trigger unit 77 and the counter 84.
Reset.

Unit 34 (Figs. 1, 3, 7) for repeated measurements of electrophysical parameters of core sand
) operates as follows.

The signal from decoder 89 of unit 33 is applied to input 95 of flip-flop 94 and activates flip-flop 94. Therefore, the output terminal 97 of the flip-flop 94 outputs a signal "1", and the output terminal 103 outputs a signal "0". The output signal at the output terminal 97 of the flip-flop 94 is applied to one input terminal 99 of the AND gate 88, and the other input terminal 99 is applied to the pulse oscillator 3.
8 output pulses are applied. Therefore, a pulse signal appears at the output end of AND gate 98.
The output terminal of the AND gate 98 is connected to the input terminal of the unit 35, and "1" is subtracted from the contents of the unit 35 each time a pulse arrives. Thus, the content of unit 35, defined by the output signal of unit 32, decreases by "1". unit 3
When the content of 5 becomes "0", unit 35 sends out a match signal and the comparison is performed. At the same time, when a signal is applied from the output 97 of the flip-flop 94 to the input 99 of the AND gate 98, the same signal is also applied to the input 101 of the sawtooth voltage generator 100, starting the voltage generator 100 to zero. Generates a signal that increases linearly from . This signal is applied to the input of voltage comparator 104. The other input 42 of the voltage comparator 104 is supplied with the output signal of the detection device 13 which is proportional to the electrical conductivity of the core sand 7 . When the voltages at input terminals 42 and 105 become equal,
Comparator 104 generates a signal and sends it to switch 6. A signal applied to input 96 of flip-flop 94 resets flip-flop 94, causing its output 97 to be a "0" and its output 103 to be a "1". Each pulse causes AND gate 98 to block and voltage generator 100 to
A signal applied to the input 102 of the flip-flop 94 resets the flip-flop 94.

Operation mode selection switch 36 (Fig. 3, 8)
Figure) operates as follows.

In the first mode of operation, the output signal of the comparator 104 is applied via the switch device 106 to the input of the unit 31 and to the output signal amplifier 37. The output signal of unit 35 is applied via switch device 107 to input 96 of unit 34 to reset unit 34. The same signal is applied via AND gate 109 and switch device 108 to input 80 of OR gate 76 of unit 33. This causes the mode of operation to be repeated. Output terminal 5 of AND gate 46 of unit 31
If the enable signal is generated at 1, the aforementioned signal passes through the OR gate 109.

In the second mode of operation, the output signal of the comparator 104 is applied via the switch device 106 to the input 96 of the unit 34 and also to the AND gate 107.
If an enable signal is generated at the output terminal 51 of the AND gate 46 (FIG. 4) of the unit 31 via the switch device 108, the output signal is applied to the input terminal 57 of the OR gate 53 of the unit 31. The output signal of unit 35 (FIG. 8) is connected to input terminal 5 of unit 31 via switch device 107.
0 and is applied to the output signal amplifier 37.

The detection device of electrophysical parameters of core sand is
It varies depending on the size of the core to be manufactured. Detection device 1 used for manufacturing small and medium sized cores
3 (FIG. 1) operates as follows.

In this case, it is sufficient to monitor the degree of hardening of the surface area of the core. However, before filling the core box 3 with the core sand 7, the plug 22 is removed from the main body 14, a screwdriver is inserted into the slot 21, and the electrode 1 is removed.
Screw in 5. By this screwing, the plug 20
The length of the electrode 15 that protrudes from the surface depends on the desired surface layer thickness determined experimentally. The plug 22 is screwed back into the main body 14 side. If necessary, the length of the electrode 15 protruding from the end face of the plug 20, and thus the layer thickness, can be varied by rotating the electrode 15 during operation.

When monitoring the curing of large-sized cores, the second
The electrode 120 (FIG. 9) can be used, and in addition to monitoring the hardening of the surface layer on the wall of the core box 3, it is possible to monitor the hardness inside the core sand. This is because the core sand 7 needs to be fully hardened in order to produce relatively thick layers.
If the surface layer is thin, the surface layer will fully cure faster than the interior of the core.

Ring 121 (10th
) is different from the material of electrode 15 (for example, electrode 1
5 is made of copper, and the ring 121 is made of aluminum), the conductivity of the core sand 7 and the electromotive force that changes similarly to the conductivity can be measured.

If the direction in which the completed core is pulled out of the core box 3 does not coincide with the longitudinal axis of the electrode 15, the detection device 13 detects the sleeve 123 (the 11th
(Fig.), so it can rotate. For this reason, the sleeve 1 is attached to the portion 4 of the core box 3.
23 to remove the electrode 15 from the hardened core sand 7.

Next, specific examples of this invention will be further explained.

Example 1 Core sand containing 3% phenolic alcohol with density ρ=1226 Kg/m ³ and 97% silica with grain size 0.16-0.2 mm is used.

The core sand was placed in the shell of a device for determining electrical conductivity (not shown), and the electrical conductivity of the core sand was measured. For the above core sand, the conductivity is 153
It was ×10 ^-5 S.

The core sand was then hardened and a minimum value of conductivity corresponding to the fully hardened state was established. This value is 4.2
It was ×10 ^-5 S.

However, the range of change in the conductivity of the core sand was 153×10 ^-5 −4.2×10 ^-5 =148.8×10 ^-5 S.

Cores made from the core sand were then pulled out of the core box at various conductivities. After the core had completely cooled, its strength was determined using known methods. In this example, the core sample (briquette) was cured in a core box heated to 230°C. The measured parameters are shown in Table 1.

The minimum value of conductivity for core sand 7 in this example is 4.2
It can be seen from the analysis of the data that the temperature was ×10 ^-5 S.
However, the strength of the core pulled out from the core box with this conductivity is 1.21 MPa. However, the conductivity
If the core is pulled out of the core box 3 at 4.25×10 ^-5 S, the strength is 1.28 MPa, which is the maximum for the core sand in this example.

[Table] The ratio of conductivity to the width of change is 1.25×10 ^-5 /148.8×10 ^-5 ×100% = 2.86% to 2.9%. In this way, the ratio of the conductivity change width to
Maximum strength can always be obtained by drawing a given core from core box 3 with a conductivity of 2.9%.

This value, the 2.9% change in conductivity, is constant for a given core and is always determined solely by the heat retention properties of the core.

Example 2 A core having a mass of 16 kg was manufactured using the core sand of Example 1. The range of change in conductivity for this core sand was 153×10 ^-5 −4.2×10 ^-5 = 148.8×10 ^-5 S.

The strongest core was obtained when the core was pulled out of the box with a conductivity of 22.3×10 ⁻⁵ S.

The ratio of the conductivity to the change width was 22.3×10 ⁻⁵ /148.8×10 ⁻⁵ ×100%=14.99% to 15%.

Thus, the maximum strength of the large core is obtained when the core is pulled out of the core box 3 with a conductivity change range of 15%.

According to this invention, since the binding properties of the binder are effectively used, the curing properties can be improved.

Further, according to the present invention, power consumption can be reduced.

Furthermore, according to this invention, manufacturing efficiency can be increased by 10-15%.
The casting material can be increased and reduced by 15-20% to produce high quality cores.

Commercial Applications The invention is also applicable to the manufacture of products from other materials such as plastic materials whose electrophysical properties change during curing.

The invention is most preferably applied to the production of hot box cores.

Furthermore, the invention is suitable for the production of cores from self-hardening sand and for the production of cores from gas-catalytically hardened core sand.

[Brief explanation of drawings]

The invention will be explained in more detail by means of examples with reference to the accompanying drawings in which: FIG. FIG. 1 is a sectional view of a core manufacturing apparatus for carrying out the core manufacturing method according to the present invention, and FIG.
A longitudinal section showing the transmitter of the electrophysical parameters of the core sand with one movable electrode, FIG. 3 shows the system diagram of the measurement logic unit, FIG. 4 shows the system diagram of the trigger unit, FIG. Figure 6 shows the system diagram of the unit for initial measurement of the electrophysical parameters of the core sand; Figure 6 shows the system diagram of the cycle control unit; Figure 7 shows the system diagram of the unit for repeated measurements of the electrophysical parameters of the core sand. System diagram, FIG. 8 is a system diagram of an operation mode selection switch, FIG. 9 is a longitudinal cross-sectional view of a device for detecting electrophysical parameters of core sand with two movable electrodes, and FIG. 10 is a ring-shaped A longitudinal sectional view of the device for detecting electrophysical parameters of core sand as shown in FIG. 2 with a second electrode; FIG. 11 shows a device for detecting electrophysical parameters of core sand as shown in FIG. 1 with a sleeve; A vertical cross-sectional view of the device.