JPH081020A - Method for automatically controlling clearance of grinding mill - Google Patents

Abstract

PURPOSE:To inexpensively maintain a specified clearance at all times with simple constitution by repeating operations of rising a grinding wheel by a servo motor to be pressed to a stationary grinding wheel, determining the zero position of a clearance and lowering the rotary grinding wheel from this position so that the prescribed clearance is maintained at all times. CONSTITUTION:The torque limit value of the servo motor 13 is set at 50% of the max. permissible torque of its output shaft and the set value of the clearance is set at 100mum. An operation is started in the state of sufficiently parting the rotary grinding wheel 4 from the stationary grinding wheel 1 and immediately, the rotary grinding wheel 4 is risen to be pressed to the stationary wheel 1, and further is risen until the torque limit value is attained. The servo motor 13 is thereafter stopped to stop rising of the rotary grinding wheel 4 at the time the torque limit value of 50% is attained. The servo motor is then immediately run reversely to lower the rotary grinding wheel and the lowering of the rotary grinding wheel is stopped at the initially set clearance value. This operation is automatically executed for about 30 minutes at 10-second intervals. Resins which are materials to be treated are thrown and the frictional crushing operation is continuously executed during this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically controlling the clearance of an attritor for producing ultrafine particles which can be used in the fields of food, chemistry, medicine, fuel and the like, and is realized by a particularly simple mechanism.

[0002]

2. Description of the Related Art Fish and livestock bones can be processed into a paste-like food material that does not touch the tongue in a single process and with a yield of 100%, and special resin and chemical raw materials have been made into ultra-fine particles. As shown in FIG. 2, a conventional grinder for producing a carbide colloidal fuel composed of heavy oil and water has an upper lid (17) having a feed hopper (16) attached to the center thereof, and has a flat grinding surface on the outer peripheral portion thereof. A ring-shaped fixed grindstone (18) having a conical truncated cone shape formed inside is continuously fixed to the surface, and has a grinding flat surface facing upwards facing the fixed grindstone (18). A rotary grindstone (19) having a truncated cone-shaped portion is driven by a separately placed main motor to drive the V belt and V
A spline shaft (21) provided on the main body (20) of the grinder that rotates via a pulley and a turntable (22) that rotates together.
It has a structure in which it is fixed by means of a grindstone holding metal fitting (23).

Further, the upper lid (17) attached to the upper end of the main body (20) by the clamping lever (24) has one end connected to the main body (20) by a support shaft (25) which is rotatable in the vertical direction. Open the fixed wheel (1) by opening (17) upward.
8) and the rotary grindstone (19) face each other on the flattened surface, which is useful for replacement and maintenance of the grindstones (18) (19).

When using such a grinding machine, the upper lid (17) is fixed to the upper part of the main body (20) by the clamping lever (24), and the grinding surface of the fixed grindstone (18) and the rotary grindstone (19). Facing each other, loosen the lock handle (26) at the center in the height direction inside the main body (20), rotate the adjustment handle (27) to raise the rotating grindstone (19), and the grinding flat surface of the grindstone The position where the upper fixed grindstone (18) is in contact with the grinding flat surface is read by the pointer (28), and the adjustment handle is used to obtain a fine particle having a desired particle size between the grinding flat surfaces based on this reading position. The rotating grindstone (19) is lowered at (27) to set the required clearance, and then the lock handle (26) fixes the clearance.

Next, the main motor is started to rotate the rotating grindstone to be connected, and the raw material is put into the supply hopper (16). As shown in FIG. 2, the fed raw material is supplied from the inner peripheral portion of the ring-shaped grindstones (18) (19) to the flat grinding surface by the centrifugal force of the rotary grindstone (19), and the strong shearing force generated there, After being gradually made into ultrafine particles by the force of friction, compression grinding, etc., it is discharged to the discharge part (29) formed in a ring shape on the outer periphery of the ring-shaped grindstone (18) (19), and further to this discharge part. Emitted from the connected outlet. Note that (30) indicates a bearing.

As described above, the grinder has to continuously and stably obtain ultrafine particles having a constant particle size. Therefore, the clearance between the grinding flat surfaces of the upper and lower grindstones is extremely important, but conventionally the clearance is manually set before starting, and the clearance cannot always be kept constant depending on the raw material and the required particle size.

Further grinding of the raw material causes abrasion of the surface of the grindstone, which changes the initial clearance, and when continuous operation is continued in this state, coarse particles larger than the desired particle size are mixed into the product, resulting in quality No stable product can be obtained. Therefore, conventionally, it is necessary to manually adjust the clearance at regular intervals, which is a particularly difficult task when a large number of machines are operated at the same time or when an automated line is constructed.

Further, the machine body and the grindstone are thermally expanded due to the heat generated by the temperature of the raw material and the friction at the time of grinding, and the clearance is narrowed. As a result, abnormal wear on the ground surface and overload caused machine failure. Further, it takes about 30 minutes to stabilize the expansion of the grindstone, and during this time, it is still necessary to manually adjust the clearance little by little, which is a great burden on the operator.

To address such a problem, the present applicant has already proposed a device capable of automatically adjusting a minute clearance between ground flat surfaces (Japanese Patent Publication No. 3-51464). In this grinder, the rotary grindstone is moved up and down using a servo motor instead of the manual adjustment handle that moves the grindstone up and down, and the load of the main motor that rotationally drives the grindstone is constantly detected. However, the clearance is kept at a predetermined value by rotating the servomotor forward or backward depending on the magnitude.

[0010]

However, when the grinder was operated by the above method, the following problems occurred. That is, when water is poured between the grindstones to set a reference state in which the clearance between the upper and lower grindstones is zero, the lower rotary grindstone is rotated, and then the rotary grindstone is raised to contact the upper fixed grindstone. The change in the load of the main motor is shown in FIG. 3, but the load is about 7 kW even when the upper and lower grindstones are in strong contact. On the other hand, Fig. 4 shows the change in load when resin is actually crushed with the same grinder. The load changes randomly from 2kW to 20kW. It was very difficult to detect with a signal. Therefore, it has been demanded to carry out the automatic adjustment of the clearance by a more reliable method.

[0011]

As a result of studies in view of this, the present invention has developed a method of keeping the clearance constant at a lower cost with a simpler structure.

That is, the clearance automatic control method of the attritor according to the present invention has a ring-shaped upper portion having an attrition flat surface on the outer peripheral portion, and a concavity-shaped truncated cone portion formed inwardly continuously from the flat surface. A fixed grindstone and a ring-shaped lower rotary grindstone are installed vertically with these grinding flat surfaces facing each other, and at the time of operation of a grinder equipped with a servomotor having a torque limiting function for vertically moving the lower rotary grindstone. The servomotor is driven to raise the lower rotary grindstone to zero the clearance between the grinding flat surfaces, and the lower rotary grindstone is immediately lowered to the predetermined clearance after the servomotor is stopped by the torque signal of the servomotor at that time. This operation is characterized by intermittently repeating the operation several times.At this time, the clearance is set to zero, and immediately thereafter, the rotating grindstone is lowered to the predetermined clearance. An operation for, after starting the operation of the grinder is repeated a plurality of times by shortening the time interval is valid.
Still another aspect of the present invention is characterized in that the rotary motor and the fixed grindstone are automatically rubbed with each other by maintaining a state where the clearance between the rotary grindstone and the fixed grindstone is zero at a predetermined torque value by the servomotor of the grinding machine. It is an automatic driving method.

[0013]

As described above, the conventional method of automatically detecting the load of the main motor and automatically driving the servomotor for moving the lower rotary grindstone up and down by this signal is because the load fluctuation range is too large. It was extremely difficult to feed back to the control of and use. Therefore, the present invention adopts a method that is not affected by the fluctuation of the load of the main motor at all. That is, by utilizing the torque limiting function of the servomotor, the rotary grindstone is raised by the servomotor and brought into contact with the fixed grindstone to determine the zero position of the clearance, and the rotary grindstone is lowered from the position so that the clearance is always a predetermined clearance. The operation is performed a plurality of times during operation.

The servomotor is a drive source for moving the rotary grindstone up and down. According to its torque control function, when the torque applied to the output shaft of the servomotor reaches a preset torque value, the servomotor is operated. The motor can be stopped and its position can be defined as zero clearance. Therefore, the desired clearance can be obtained by lowering the rotary grindstone from the zero position to reverse rotation of the servo motor until the clearance reaches a predetermined clearance. If the above-mentioned operation is frequently performed, the clearance is always maintained at a predetermined value in response to the change in the clearance due to the thermal expansion of the machine body or the grindstone and the change in the clearance due to the abrasion of the grindstone surface due to the grinding and grinding of the raw material. Will be.
It is desirable to shorten the time interval for repeating the above operation for about 30 minutes immediately after the start of operation, because the clearance changes greatly due to the expansion of the grindstone.

If the torque limiting function of the servomotor is used, the rotary grindstone and the fixed grindstone can be automatically fitted to each other. That is, since the surface of these grindstones is too uneven especially before use, it is necessary to rub them together to remove extreme protrusions. In the present invention, in order to carry out this, an operation of automatically maintaining a state in which the clearance between the rotating grindstone and the fixed grindstone is zero for a predetermined time at a preset torque limit value of the servomotor is performed.

[0016]

Next, the present invention will be described with reference to examples.

FIG. 1 shows the main part of the grinder used. A ring-shaped fixed grindstone (1) similar to that shown in FIG. 2 is fixed to an upper lid (2) to which a supply hopper is attached, and a ring-shaped rotary grindstone (4) fixed on a rotating disk (3) is provided facing the upper lid (2). It was The rotating disk (3) is spline-fitted into a connecting cylinder member (7) which is integral with the main shaft (6) of the main motor (5) and is connected to a spline shaft (8) which is vertically slidable. . The spline shaft (8) is vertically and integrally rotatably connected to a supporting member (10) having a screw formed on the outer periphery thereof through a bearing (9) in the up-down direction so as to rotate below the supporting member (10). A connecting pin (12) protruding from a lower bevel gear (11) is inserted into the end face. Therefore, when the servo motor (13) is driven, the bevel gear (11) is rotated by the output shaft gear (14) attached to the output shaft of the servo motor (13), and the support member (10) connected thereto is rotated. Since the screw on the outer periphery is screwed into the female screw part (15) fixed to the machine body, the supporting member is moved up or down, and therefore the rotary grindstone (4) is moved up or down to reduce the clearance. Change.

The automatic adjustment of the clearance when the resin is ground by such a grinder will be described. Set the torque limit value of the servo motor to 50 of the maximum allowable torque of the output shaft.
%, And the clearance setting value is 100 μm. Then, the operation is started in a state where the rotary grindstone is sufficiently separated from the fixed grindstone, and the rotary grindstone is immediately raised and brought into contact with the fixed grindstone until the torque limit value is reached. After that, when the torque limit value of 50% is reached, the servo motor is stopped to stop the rising of the rotating grindstone, immediately reversely rotate to lower the rotating grindstone, and stop the descending of the rotating grindstone at the initially set clearance value.

This operation was automatically performed at intervals of 10 seconds for about 30 minutes, during which the resin as the treated material was charged to continuously perform the grinding operation. Since the thermal expansion of the grindstone became stable after 30 minutes, the change in clearance was mainly due to the constant wear of the grindstone. The above operation was performed at intervals of about 10 minutes by increasing the time interval. As a result, a resin ground powder having a uniform particle size was always obtained.

[0020]

As described above, according to the present invention, the clearance between the rotary grindstone and the fixed grindstone is always kept constant with an inexpensive structure, so that the grain size of the ground product is always kept at a constant level. it can. Further, since such clearance control can be automatically performed, it has a great effect in automating a production line using a grinder.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part for explaining a method of the present invention.

FIG. 2 is a side sectional view illustrating a conventional method.

FIG. 3 is an actual measurement diagram showing a change in load of a main motor when a rotary grindstone and a fixed grindstone are brought into contact with each other in a grinder.

FIG. 4 is an actual measurement diagram showing fluctuations in the load on the main motor when resin is processed in a grinder.

[Explanation of symbols] 1 ring-shaped fixed grindstone 2 upper lid 3 rotary disk 4 ring-shaped rotary grindstone 5 main motor 6 main shaft 7 connecting cylinder member 8 spline shaft 9 bearing 10 support member 11 bevel gear 12 connecting pin 13 servo motor 14 output shaft gear 15 Female thread 16 Supply hopper 17 Top lid 18 Ring-shaped fixed grindstone 19 Ring-shaped rotary grindstone 20 Grinding machine main body 21 Spline shaft 22 Rotating plate 23 Grindstone restraint 24 Clamping lever 25 Support shaft 26 Lock handle 27 Adjustment handle 28 Pointer 29 Discharge Part 30 bearing

Claims (3)

[Claims] 1. A ring-shaped upper fixed grindstone and a ring-shaped lower rotary grindstone having a ground flat surface on the outer periphery thereof, and a conical truncated cone portion having a concave shape formed continuously inside the flat surface. These grinding flat surfaces are placed facing each other in the vertical direction, and the lower rotating grindstone is driven by driving the servomotor during operation of the grinder equipped with a servomotor having a torque limiting function for vertically moving the lower rotating grindstone. To raise the clearance between the grinding flat surfaces to zero and to lower the lower rotary grindstone to a predetermined clearance immediately after stopping the servo motor by the torque signal of the servo motor at that time, and repeating the operation intermittently a plurality of times. A characteristic automatic clearance control method for a grinding machine. 2. The automatic clearance control of the grinder according to claim 1, wherein the operation of setting the clearance to zero and then immediately lowering the rotary grindstone to a predetermined clearance is repeated a plurality of times with a short time interval immediately after the start of the operation of the grinder. Method. 3. The automatic grinding of the rotary grindstone and the fixed grindstone by maintaining the clearance between the rotary grindstone and the fixed grindstone at a predetermined torque value by the servomotor of the grinder according to claim 1. The automatic driving method characterized by.