JP4956482B2 - Roll mill - Google Patents

Description

  The present invention relates to a roll mill used for wet dispersion, and more specifically, substances such as fine powder and nanoparticles in a processing material in the manufacturing process of inks, paints, ceramics, chemicals, foods, electronic materials and other various products. The present invention relates to a roll mill that is used for kneading and dispersing.

  A three-roll mill in which three front rolls, middle rolls, and rear rolls are juxtaposed in the transverse direction is widely used to knead and disperse substances such as fine powder and nanoparticles in the treatment material. In this roll mill, the load acting between the rolls is detected by a load sensor (load cell), and the distance between the rolls is adjusted by moving the front roll and the rear roll with a manual handle (for example, patents) Reference 1). If automatic control is simply performed by a servo motor or the like instead of such a manual handle, the following various problems occur, and accurate automatic control is difficult only by control using a load sensor.

  First, as shown in FIG. 1, the rear roll and the front roll are provided with flanges on both ends of the rear roll and the front roll, which are movably provided on the gantry (frame). Then, the pressing force is applied, and the bearing of the flange of the other middle roll is fixed to the gantry. Therefore, there is a “pressing pressure b” on the push side roll contact line of both rolls, and a “reaction force a” is generated on the fixed side roll contact line. As shown in FIG. 2, the pressing force (contact reaction force) is not a curve such as c or d on the contact line, but a constant value distribution (flat single line) on the surface of the roll. , R2 are provided. The push side roll and the fixed side roll rotate at different rotational speeds, and are driven so that a frictional force is generated between the two rolls. This frictional force also plays a part in the dispersion effect.

The pressing force (or reaction force) and the crown on the roll surface have a delicate relationship with a certain correlation, and this correlation must be theoretically related to the relationship between the proper cause and the result. Further, it has been found that the frictional force applied between the two rolls has an influence on the pressing force (or reaction force), and the influence cannot be ignored as a variation of the pressing pressure. That is,
(Extrapolated pressure: P1, P2) = (Pressure on contact line) + (Change due to frictional force)
Thus, the extrapolation pressing pressure is not directly the pressing pressure on the contact line.

  For such a phenomenon, basically, a finite element analysis model of a combination of these two contacting rolls is created, and a nonlinear analysis is performed in which the contact portion expands while increasing the load for a while on the contact line. Based on the analysis, the pressing pressure P1 from the rear roll, the pressing pressure P2 from the front roll, the crown R1 of the rear roll, the crown R2 of the middle roll, the crown R3 of the front roll and the distance δ1 between the rear roll and the middle roll, The relationship between the distance δ2 between the middle roll and the previous roll is specifically obtained.

  As for friction between rolls, as described above, it is known that if there is friction, it is involved as a variation and drags the required “pressing pressure” to the wrong side. Therefore, the pressing pressure of each of the rolls and the distance between the rolls can be found by maintaining the relationship of P1, P2, δ1, and δ2 when there is no friction. For this purpose, the remainder excluding P1 and P2, and δ1, δ2 It can be seen that it should be used as a control index. Therefore, it is only necessary to control the roll mill so as to maintain the displacement control, that is, the distances δ1 and δ2 between the rolls determined at the beginning of machining.

  More specifically, the roll mill has a fixed roll size, and in addition, there is a pressing force on dispersion processing required by the user. First, the static analysis of the roll is performed once using these. From this result, it will be understood what value the crown curve shape and curve peak value (usually in the center) of the crown will be added to the roll. Next, this analysis result is incorporated into a roll analysis model with a crown added. Two of these models are used as a contact analysis model in which only the central crown peak portion is contacted from the beginning. One of the rolls is a fixed roll, the both ends of the roll are supported, and the finite element method nonlinear contact analysis is performed according to the load increment method by the procedure of applying the same load from both ends of the other roll. Therefore, the load is finely divided into each step and finally reaches P1 or P2. The result is such a shape as shown in “constant reaction force” in FIG. From this result, a distribution having a constant pressing pressure (or reaction force) on the contact line is obtained, and at this time, R1, R2, R3, P1, P2, δ1, and δ2 are obtained as correlation values. Among these, R1, R2, and R3 are used as crown amounts at the time of roll design, and the remaining P1, P2, δ1, and δ2 are values used for automatic control.

  As described above, the control may be performed by the displacement control. However, since the displacement control alone has the following problems, it is necessary to make a partial correction in addition to the displacement control. First, the following inconvenience arises due to load imbalance at the left and right ends of the roll. As shown in FIG. 3, normally, the contact line pressure between the rolls is almost a flat distributed load when balanced with the crown shape added to the rolls. However, in reality, if AC = L2 and CB = L1 in FIG. 3, the center point C of AB / 2 = L1 = L2 is a slightly large distributed load.

  Further, since it is simpler to consider this distributed load by replacing it with the concentrated load at C in the analysis, it is considered that the concentrated load P2 (P1) is working here. Then, it can be seen that moments P2 × L1 and P2 × L2 are acting on the roll on both sides of the point C. For example, the contact line pressure distribution may be inclined as shown in the lowermost part of the figure due to some disturbance. At this time, P2 deviates from the center point C, that is, L1> L2 (of course, there is also L2> L1). At this time, if the load is controlled, the total P2 does not change. As a result, the moment becomes P2 × L1> P2 × L2, and a moment difference between the left and right is generated. Then, P2 is pulled toward the L1 side (B side), that is, the larger moment due to this moment difference. In the opposite case, it is pulled to the A side. Thus, P2 always has a self-alignment force in which a force to stay at the center point C is working.

  However, if the feedback control is only displacement control, the above self-alignment force does not work. Specifically, according to the displacement control, the load imbalance at the left and right ends of the roll should be corrected. However, when actually operating, the displacement control alone causes a subtle unbalance at both ends of the roll. However, even if it did not appear in the numerical error in displacement, there was often a phenomenon that a delicate imbalance was detected as a load.

  Further, when examining the “relationship between load and displacement” during actual operation and the “relationship between load and displacement” during static operation, when the pressure P2 (P1) is applied to the roll as described above, FIG. As shown in FIG. 4, naturally, the contact portion is a circle that is somewhat crushed when viewed in cross section. That is, if the radius of the roll is R and the distance between the roll axes is D in FIG. If the crushing allowance at this time is 2R−D = 2d, it can be said that d is a crushing allowance for one roll.

  Then, if we say that the actual displacement control operation is started as the distance D between the roll axes when the material is introduced, “D + e” which takes into account the clearance e between which the material is sandwiched is considered as the actual value of the displacement control. I'm driving. Therefore, it is necessary to adjust whether or not the load coincides with P2 (P1) obtained statically during displacement control operation during operation. At this time, the monitor value of the load cell is detected and coincides with P2 (P1). It is necessary to drive at “D + e”.

  Furthermore, it is a well-known fact that when a dispersion-treated material is put into a three-roll mill, the viscosity of the material tends to decrease as the dispersion proceeds depending on the inherent properties of the material. Assuming that this machine was used after being circulated a number of times, if only “displacement control” is maintained as the viscosity decreases, the load on the material may decrease with each pass. . Currently, there are almost no examples in the industry that use a three-roll mill after many passes. In such a case, a load cell (load) monitor is necessary, and when the viscosity drop of the material becomes noticeable over a certain width, the correction can be executed on the program without any external changes. If it is a mechanism that can be used, the user can perform the distribution as intended by a single process. As described above, although the operation control is displacement control, it is preferable that a mechanism for monitoring the load with a load cell (load sensor) and adjusting the variation by a program is provided.

There is also a problem when an abnormal load occurs. If an object larger than normal is mistakenly mixed between the rolls during operation of the three-roll mill, if only "displacement control" is used, a huge load will be generated trying to maintain the displacement. It is also assumed that the function of the machine is impaired. In order to cope with this, a load cell for load measurement (load sensor) is inserted into the control system to avoid a huge load and protect the machine at the moment when a sudden trigger-like displacement is unavoidable. A program to go to is also possible. The load cell is also effective in incorporating the so-called “safety measures against abnormal loads” into the system.
Japanese Utility Model Publication No. 1-83438 (drawing)

  The problem to be solved by the present invention is to provide a roll mill capable of solving the above-mentioned drawbacks due to displacement control or load control and controlling the distance between rolls by fully automatic control to improve the dispersion quality.

  According to the present invention, in order to solve the above problems, in a roll mill used for kneading and dispersing substances such as fine powder and nanoparticles in a processing material, a fixed roll fixed on a gantry, It has a moving roll that can be moved to and away from the fixed roll. The moving roll can be moved minutely in the direction perpendicular to the roll by a servo motor and a ball screw, and the distance between the fixed roll and the moving roll is measured. A load sensor for measuring the pressure between the rolls is provided, and a detection signal generated over time from each sensor is fed back to manage a fixed distance and a constant pressing pressure between the fixed roll and the moving roll. An electronic automatic control mechanism is provided, and the servo motor is driven by the electronic automatic control mechanism to sequentially position the moving roll. Roll mill, characterized in that so as to integer is provided. The roll mill is a three-roll mill having three rolls juxtaposed in the horizontal direction. The middle roll fixed at the center on the gantry is a fixed roll, and the front roll and the rear roll provided before and after the middle roll. There is provided a moving roll that can automatically control each roll.

  Since the present invention is configured as described above and is automatically controlled by feedback control so as to maintain a predetermined distance between rolls over time by using both displacement control and load control, on the contact line using the roll with crown A constant pressing force (reaction force) distribution can be obtained, and without losing the dispersion effect from the frictional force resulting from the differential rotation of the roll, self-alignment, roll crushing allowance, viscosity change of processing material, abnormal load A roll mill such as a three-roll mill that can be operated under a constant roll contact force that is always planned in response to occurrence, etc. is obtained. By using this roll mill as a disperser, high dispersion quality (accuracy) requirements are met. It became possible. In other words, the particle size distribution after dispersion can be obtained with a narrower width, and automatic control makes it possible to transfer a part (skilled technique) that relied on human control technology from a person to a machine.

  The present invention relates to various kinds of materials used for kneading / dispersing substances such as fine powders and nanoparticles in processing materials in the manufacturing process of inks, paints, ceramics, chemicals, foods, electronic materials and other various products. Although it can be applied to a roll mill, in FIGS. 5 and 6, as an embodiment of the roll mill of the present invention, a central middle roll 1 is fixed, and a front roll 2 and a rear roll 3 are contacted before and after the lateral direction. A three-roll mill provided in parallel so as to be separable is shown. In FIG. 5, a bearing 5 that supports the roll shaft 4 of the middle roll 1 is fixed to a gantry (frame) (not shown), and a front roll 2 and a rear roll 3 are located on both sides thereof.

  The front roll 2 and the rear roll 3 are attached to the gantry with almost the same mounting structure. FIG. 6 shows an embodiment of the mounting portion, and on the left side of the figure is a servo motor bracket 6 fixed to the gantry. A servo motor (not shown) dedicated to displacement driving is suspended and fixed above, and the rotational force of the servo motor is transmitted to the ball screw coupling 7. At the same time as the rotational force is transmitted, the reaction force transmitted through the ball screw 8 is also received and transmitted to the motor bracket 6. For this reason, a bearing 9 is incorporated between the two, and a load cell (load sensor) 10 for measuring the reaction force is mounted between the bracket 6 and the bearing 9 together.

  The ball screw 8 and the ball screw coupling 7 are firmly connected by key connection, and the rotational force is transmitted to the ball screw. In the ball screw, the rotational force is converted into a forward force (propulsive force), and the forward force (propulsive force) is transmitted to the roll bearing holder 12 via the roll push bar 11.

  The ball screw 8 and the roll push bar 11 are mounted on the same screw fixing plate 13, and an LM (linear motion) guide 14 is mounted on the screw fixing plate. A similar LM guide 15 is also mounted on the roll bearing holder 12, and these two LM guides are made to move on two common rails, and the linearity of both is maintained. .

  A roll shaft 16 of a rear roll (front roll) main body is assembled to the bearing in the roll bearing holder 12. A drive motor (not shown) is connected to the roll shaft 16 via a Schmitt coupling 17. Since the Schmitt coupling 17 is a mechanism that enables parallel movement of the shaft during rotation in power transmission with a different axis, this mechanism allows rotation from the drive motor while allowing movement in a direction perpendicular to the roll shaft 16. The driving force can be transmitted to the roll shaft 16 at a constant speed.

  In order to accurately measure the distance between the servo motor bracket 6 and the roll bearing holder 12, a laser displacement meter (laser sensor) 18 is fixed to the servo motor bracket 6, and a laser beam is applied to the opposite surface of the roll bearing holder 12. Measuring distance.

  Since the servo motor bracket 6 is fixed to a frame and the bearing 5 of the roll shaft 4 of the middle roll 1 is also fixed to the frame, the intermediate roll is measured by measuring the distance between the servo motor bracket 6 and the roll bearing holder 12. The distance between the roll shaft 4 and the roll shaft 16 of the rear roll 3 (front roll 2) can be measured. The distance between the servo motor bracket 6 and the roll bearing holder 12 is determined by the initial pressing pressure (static) when the roll is stationary, and thereafter, feedback control is performed to keep this constant during roll driving. For this control, a ball screw propulsion force by a servo motor rotational force is used. In addition, an electronic automatic control mechanism is provided so that the servo motor is instantaneously driven by feedback control and managed at a constant distance and a constant pressing pressure.

  As shown in FIG. 5, the control system shown in FIG. 6 is installed at a total of four locations, the left and right ends of the front roll 2 and the left and right ends of the rear roll 3, and these are fixed on a frame on the same plane or via LM guides. The left and right ends of the middle roll are fixed on the gantry. Therefore, when the roll mill is operated, the laser sensor 18 and the load sensor (load cell) 10 cause the distance between the rolls and the pressure between the rolls acting on the roll to be instantaneously and instantaneously. Therefore, the detection signal from the sensor is fed back. By driving the servo motor and finely moving the roll shaft 16 in a direction perpendicular to the roll, the optimum operation can be performed fully automatically at a constant distance and a constant pressing force, and the dispersion effect can be improved.

Schematic which shows a crown curve, a roll contact line, etc. at the time of contacting under fixed pressing pressure of a fixed roll and a push side roll (moving roll). The figure which shows the distributed pushing pressure (reaction force) on the contact line in a roll contact state. Explanatory drawing of the pressing force distribution on a contact line, and a self-alignment force. The figure of the distance between rolls with the crushing allowance of a roll when pressing pressure is applied. The top view of the roll mill which shows one Example of this invention. The front view which shows the attachment part to the mount frame of a moving roll.

Explanation of symbols

1 Middle roll 2 Front roll 3 Rear roll 10 Load cell (load sensor)
16 Roll axis 18 Laser displacement meter (laser sensor)

Claims (4)

  In a roll mill used to knead and disperse substances such as fine powder and nanoparticles in processing materials, it has a fixed roll fixed on a gantry and a movable roll provided so as to be able to contact and separate from the fixed roll. The moving roll is provided by a servo motor and a ball screw so that it can be moved minutely in the direction perpendicular to the roll. A laser sensor is provided between the fixed roll and the moving roll to measure the distance between the rolls, and the inter-roll pressing pressure is measured. Equipped with an electronic automatic control mechanism that feeds back a detection signal generated over time from each sensor and manages a fixed distance and a constant pressing force between the fixed roll and the moving roll. A roll characterized in that the servo motor is driven by a mechanism to sequentially adjust the position of the moving roll. Le.   The roll mill is a three-roll mill having three rolls arranged in parallel in the horizontal direction. The middle roll fixed at the center of the gantry is a fixed roll, and the front roll and the rear roll provided before and after the middle roll are moved. In order to make the contact line pressing force between each roll between the middle roll and the front roll and between the middle roll and the rear roll equal at any position on the contact line, the servo motor and ball screw The roll mill according to claim 1, wherein the roll is movable in a perpendicular direction.   Crowns are provided on the front roll, middle roll, and rear roll, and the change in pressing force due to the difference in frictional force caused by the differential rotation between the pair rolls of the front roll and middle roll and the middle roll and rear roll is also added. The roll mill according to claim 2, wherein feedback is provided to an electronic automatic control mechanism.   The roll shafts of the front roll and the rear roll of the moving roll are respectively connected to a drive motor, and a Schmitt coupling is provided between the drive motor and the roll shaft of each roll to allow movement in a direction perpendicular to the roll axis. The roll mill according to claim 2 or 3, wherein the roll mill is provided.

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