JPH0986741A - Roll stand brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for mounting a brake on a roll stand arm, ensuring an easy mounting work and remarkable cost reduction. SOLUTION: A brake 26 is used for controlling the web tension of a roll stand and acts as a generator. Furthermore, the shaft 38 of the rotor of the generator is connected to the mandrel 16 of the roll stand. Also, a rotor 36 is held on the stator assembly 52 of the generator, and the mandrel 16 supports the whole of the generator. Thus, the excessive axial projection of a flexible coupling and the generator is eliminated. In another embodiment, the stator 52 of the generator is directly mounted on a roll stand arm 12, and the rotor and the stator of the generator are aligned with each other via the bearing part of the mandrel 16 of the arm 12. Also, accurate web tension can be obtained via the feedback of current regarding the control of a generator load.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake for tensioning a web of rolls supported on a roll stand, and more particularly to a brake of the type acting as a generator coupled to a load. And a brake that, when driven by a rolling roll, exerts a traction force on the roll to tension the web material unwound from the roll.

BACKGROUND OF THE INVENTION Many industrial processes for converting sheet material into finished articles begin with the material rolled into a roll stand and then rewind the sheet material from the roll. Be started by. In most of these processes, the process variable whose control is important is web tension. Thus, the braking force on the roll stand as the roll is unwound resists roll rotation and therefore tensions the web. Most brakes used for this purpose are friction brakes actuated by pneumatic, hydraulic or electromagnetic forces. When friction brakes are used, the brake pads and rotor discs or drums wear and require frequent inspection. They also generate dust that contaminates workplaces and products. Furthermore, some installations require pneumatic or water cleaning to maintain the brake temperature at a safe level and reduce the rate of brake wear. Obviously, generator-type brakes have significant advantages over friction brakes. That is, the generator type brake does not generate much wear or dust as compared with the friction brake. Moreover, the power generated by the generator is in the form of electricity and can easily be transferred to a remote ballast resistor for safe dissipation to the atmosphere or used for other processes. Another advantage of generator brakes, either pneumatically or hydraulically, is that their torque can be quickly changed by direct electronic means, and thus tension control devices are, in a sense, mechanical brakes such as brake calipers. Is potentially more responsive than using electro-pneumatic or electro-hydraulic modulators, which rely on the operation of dynamic components. It is therefore not surprising that many proposals have been made over the years to use generator brakes for this purpose. However, despite many such proposals, the type used for all web tension control is widely used for large, if not exclusive, rolls. Even large equipment using generator type brakes, in some cases, was disadvantageous in terms of cost savings compared to friction brakes. Regardless of whether the brakes are frictional or generator type, the controller may, for example, change the radius of the roll as the web material is withdrawn,
It must act to maintain the tension at the desired magnitude. An early example of such a control system is US Pat. No. 2,052 to Miller,
No. 788 is available. This is based on the recognition that a constant web tension is generated by keeping the braking force constant at a constant web speed.
Since power is the product of torque and angular velocity, the mirror places an inductor in the load circuit of the generator to reduce the angular velocity of the roll, and thus the generator, as the roll radius decreases as the web is drawn from the roll. As the output frequency-increased, the generator output current-and therefore the generator torque-
Is decreasing. A similar method in friction braking uses a sensing arm or an ultrasonic sensor to monitor the roll radius to reduce the brake torque as the monitored radius decreases and to do so with a controller that avoids increasing tension. It is being appreciated. Both the mirror invention and the roll radius detector are open loop brake torque controllers. These devices are based on measurements such as generator current and roll radius, if they are used where very high tension accuracy is not required,
It can be manufactured at a relatively low price. However, when high tension control is required, a device that controls tension more directly is drawing attention. One such solution is to use a dancer roll, i.e., a roll that moves up and down or back and forth under load, such as by gravity or a pneumatic cylinder. A constant tension is exerted on the web as long as the roll is maintained at the center of its working range. The method of controlling the brake torque in the dancer roll device is to detect the position of the dancer roll and control the brake torque to keep the position of the dancer roll substantially constant.

Dancer roll systems are relatively accurate when they fluctuate in fairly slow systems, but in some systems they are usually wide band disturbances, such as those caused by roll efficiency. There is a delay problem that reduces the responsiveness to. Furthermore, the lack of space for special equipment may necessitate refurbishment to install the dancer roll, which may make the use of such equipment impractical. Even if it is installed in the equipment from the beginning, this method is expensive. Dancer rolls, support bearings and shaft hangers are expensive. This is especially true for the wide web. The reason is that the dancer roll requires a fairly large diameter dancer roll to avoid significant deformation. The problem of being expensive is significant under the circumstances that the winding angle required to obtain the required accuracy can only be ensured by the additional provision of idler rollers. In order to reduce the problem of dancer roll delay, which is largely due to roll inertia, some devices use a load cell that measures the radial load on the idler roll and the idler roll bearing resulting from web tension. Is directly measured. The final output is compared with the target value, and the applied braking force is determined based on the error output due to the comparison. Such devices have the advantage of providing at least a high degree of accuracy, they are more responsive than the dancer roll mechanism. However, these devices have the same refurbishment difficulties as dancer roll mechanisms and at least usually are expensive.

SUMMARY OF THE INVENTION The present invention is based on the recognition that an improved method of attaching a brake to a roll stand arm can result in a significant increase in acceptability and convenience and a significant cost reduction. There is. One form of the invention is that the rotor of the generator is mounted directly on and supported by the roll stand arm itself. This is accomplished by providing a generator rotor with axial recesses. This axial recess receives the shaft of the roll stand arm, so that the rotor is mounted on and supported by this shaft. By adopting such a mounting method, in the present invention, the generator and the shaft are automatically aligned. This eliminates what was perceived as a major barrier to the widespread adoption of brakes mounted on generator roll stands. In particular, high torque flexible couplings have heretofore been used when connecting a generator type brake having a conventional shaft to the shaft of a roll stand. This is not only expensive, but also has a structure in which the dimensions are too long, and it is in a state of protruding into the working passage. On the other hand, according to the invention, the generator brake automatically eliminates this type of centering problem, which requires a flexible coupling,
Moreover, the mounting method is such that the axial protrusion is minimized in the working passage. In another aspect of the invention,
More applicable by retrofitting, the rotor shaft accepts the roll stand arm in the central recess as described above, but the stator is rotatably mounted on the rotor and the generator is mounted as a unit of the shaft. . Thereby, a shaft hang is associated with another device.
The shaft supports both the stator and the rotor, as is known as the Hung) shape. Also in this case, the centering is automatically performed without the flexible coupling. Both of the aspects of the invention benefit from another aspect of the invention, which is an improved brake control system. This aspect is based on the recognition that it is not necessary to resort to expensive methods such as dancer rolls or tension measuring devices in order to obtain the high degree of accuracy noted for brake control devices.
The principle used is that the power expended in pulling the web from the braking roll is calculated as the product of the roll torque and angular velocity or as the product of the web velocity and tension. In a sense, some open loop torque methods, such as the Meller invention described above, use such principles. However, the present invention suffices to take advantage of the fact that by equalizing these two products, the web tension can be estimated from the other three numerical values, and its determination is extremely cheap compared to measuring the tension directly. To use. In particular, the present invention senses generator current that can be measured at low cost as an indication of torque. In addition, direct measurement of the web speed and the angular velocity of the generator can be obtained at a low price using, for example, an angle encoder, so both can be directly measured, or the radius of the roll can be measured to obtain one from other values. It is also possible to estimate two numbers. The current measurement is then fed back to control the generator load in response to the difference between the measured current level and the target current level, while the other measurement displays achieve the desired tension. Needed for. This number can be accurately determined. This is because, in general, the generator current is not in a simple proportional relationship with the torque applied to the roll by the web, but the numerical value necessary for estimating the torque from the generator current can be inexpensively measured. This will become clear from the description below.

BEST MODE FOR CARRYING OUT THE INVENTION A roll stand (hereinafter referred to as a roll stand) 10 for supporting a roll of the type adopted by the present invention comprises a base 11, which is preferably extended substantially horizontally by an actuator 14. The roll stand arm 12 is supported and the actuator 14 is used to raise and lower the arm 12.
The arm 12 is provided with a bearing block which is provided with the shaft 16 of a retractable core chuck 18 or other core coupling, such as a collet, which engages the core shaft to roll the web material. 22 supports and engages it in a torsional direction. In order for the roll stand 10 to support the roll stand arm 12, the actuator 1
When an actuator such as 4 is used, the arm is usually allowed to pivot downwards when the process is stopped but the roll is not yet ejected, as indicated by the dotted lines in FIGS. As a result, the tail roll remains stationary on the floor and can be removed by rolling. To control the web tension, a brake 26 in the form of a generator driven by roll rotation is used in the present invention. In the embodiment shown in FIGS. 1 to 4, the brake is mounted while retained on the shaft and is supported by the outer protrusion 28 of the mandrel 16 as described in more detail below. In the embodiment shown in FIGS. 1 to 4, the core rod 1
6 fully supports the brake 26, but the stator of the generator must not rotate, so that the housing of the generator has the shape of the non-rotating arm 30 with which the pin 32 of the arm 12 engages. Are doing Projection 28
The mounting of the brakes eliminates the potential centering problem of having to use complex and expensive flexible couplings. Such a mounting method eliminates the need for an arrangement such as an excessively long axial braking device often found in conventional devices. Thereby, the brake is minimized from projecting into a work path through which a forklift or a transfer machine frequently passes. As shown in FIG. 3, the brake 26 is provided as a generator, the rotor 36 of which has a hollow shaft 38 which opens into a radially extending disc 40. A cylindrical magnet permeable to magnetic field lines, such as cast steel, called "backiro."
n) ”ring 42 extends axially from the outer end of disk 40 and supports permanent magnets 44. A shaft-mounted structure is possible because the recess formed by the hollow shaft 38 receives the protrusion 28 of the core rod. In the illustrated embodiment, the axially outer portion of the hollow shaft forms a radially inwardly sloping surface 46 against which bolts 48 wedge the fixed collet to secure the rotor 36 to the mandrel 16. Stick to it. This is shown in FIG. 3 and is supported by the bearing 51 of the bearing block formed by the roll stand arm 12. The generator stator comprises a stator assembly 52 which forms the outer housing as well as the hub portion 56 of the generator bearing block which carries the bearing 58, which causes the hollow rotor shaft 38 to move to the stator. Supported within. in this way,
The rotor supports the stator and the core rod 16 of the core chuck supports the rotor. As can be seen by simultaneously referring to FIGS. 3 and 4, the stator assembly 5
2 further comprises a bearing block frame portion 60 of the generator into which the core laminate 62 fits. An armature winding 64 surrounds the core stack. The shaft mounting structure of FIGS. 1 to 4 is particularly advantageous in the case of retrofitting, the new brake being mounted on an existing roll stand which was initially constructed in a different manner, but the shaft mounting structure of the invention. Are not limited to arrangements that provide the advantage of eliminating the need for complex couplings. FIG. 5 shows an alternative configuration which envisions a roll stand in which the arm is configured for mounting or replacing a generator brake. In the arrangement of FIG. 5, the rotor 36 'is supported by the core rod 16', like the rotor of the embodiment of FIGS. However, the core rod 16 'of this embodiment does not additionally support the stator assembly 52', but rather the rotor shaft 3
8'is not supported in the stator. Instead, the stator assembly 52 'is supported directly on the arm rather than through the core rod 16', which in this embodiment is mounted on a replaceable bearing cartridge 66 which is provided with a bearing housing for the arm and bolts. It is preferably fixed to the body of the arm by 68. The generator and cartridge are manufactured together in this embodiment, preferably including a retractable core chuck and core rod. By factory-assembling the generator and the cartridge as a unit, the required rotor and stator are centered and the stator is supported separately, so that the bearing for separation corresponding to the bearing 58 in FIG. It is not required for axial positioning of the stator armature and rotor magnets. That is, the rotor of the generator is carried by the arm bearing 51 'of the core rod. In both embodiments, the rotor comprises a permanent magnetic field source located radially outward of the armature winding mounted on the stator. According to the broader teachings of the present invention, such an arrangement is not necessary, but it has certain effects. Permanent magnets simplify the circuit somewhat, reduce copper losses, and constitute a relatively compact magnetic field source.
When this compact magnetic field source is located outside the armature winding, as in the illustrated embodiment, the generator gap is such that the field magnets have the same size as the generator armature winding. The radius is set to be larger than that in the case of being arranged on the inner side in the axial direction. The field-gap area, and hence traction, can be large for a given total stator assembly diameter, axial length, and acceptable copper loss. The traction force is related to the size of the radius, and the torque produced thereby is increased by the larger moment arm as well as the larger traction force. As a result, the armature copper loss and the brake temperature rise that occurs to meet the required torque are reduced. Therefore, this configuration provides a relatively simple installation for a given torque requirement and copper loss constraint. The simplicity of the installation is particularly advantageous when applied to a device designed to mount the tail roll on the floor before the chuck is released. The small generator allows a smaller tail roll to rest on the floor without interfering with the generator housing. Another advantage of the illustrated electric brake is that the maximum size of the stator iron core stack is reduced, reducing the amount of unused material produced by making these parts. Both of these factors significantly reduce the cost of manufacturing the iron core. on the other hand,
This embodiment produces maximum torque with minimum equipment size and copper loss. An alternator system can be used. For example, replacing the field magnet with an electrically conductive rod, a backing ring (back) is inserted in the slot of the rotor stacked.
The rotor of the squirrel cage type induction generator can be formed by installing an iron ring). The effect of using a generator brake is largely due to inexpensive and accurate control. This control is performed by changing the load applied to the output of the generator. The load can be changed by changing the impedance of the load circuit, by pulse width modulation of the generator voltage, or by other mechanical methods known to those skilled in the art. The type of load circuit is not difficult in principle to carry out the invention, an example of which is shown in FIG. This figure shows an armature winding 64 provided with three phases, but the other numbers of those phases are the same as those used in the embodiments of the present invention. FIG. 6 shows winding 64 connected to synchronize and rectify the output before it is applied to ballast resistor R1. The ballast resistor is usually located at a remote location where the dissipated power is transferred to the air or, for example, the fluid to be heated and removed. Of course, there is no reason why it is necessary to rectify the output of the generator before applying it to the stable resistance, but in normal equipment, the power of the generator is converted and supplied to the power line of the plant. Rectifiers are provided as it may be necessary to recover power.
Further, by adding a DC power source and operating the synchronous rectification device as an inverter, the brake acts as a motor and "plug braking".
ing) "mode to enhance roll deceleration in response to a stop or emergency stop command. This mode of operation is described in more detail below. For these reasons, control transistors Q1 to Q6 in parallel with respective freewheeling diodes D1 to D6 are provided to drive high side drive circuits 74, 76 and 78 to low side drive circuits 80, 82 and 84. Control the phase voltage applied to the high and low voltage DC supply rails 70, 72 in response to the signal. These drive circuits are controlled by the rectification control logic 86. The control logic 86 determines the position of the generator rotor φ
Determines when and what side each phase is connected to. The rotor position φ is obtained by the angular position detector 88. The angular position detector 88 may be another conventional encoder, but the angular position can instead simply be inferred from the armature winding signal. The commutation control logic 86 may be of the type commonly used for synchronous rectification, but is preferably of the type capable of controlling the duty cycle to provide a convenient mechanism for changing the generator load. For this reason, FIG. 6 is shown as having a load control signal applied to commutation control logic 86. A method of controlling the generator load will be described. The control device shown in FIGS. 7 to 9 achieves high tension accuracy by closed-loop control, similar to the conventional device. However, unlike conventional devices, the device shown closes the circuit loop by feeding back a quantity that can be measured in an inexpensive manner, namely the load current of the generator. There is no direct relationship between this amount of feedback and web tension, but this device does not allow for quantities measured by other inexpensive methods, such as web speed and magnetic flux density in the generator air gap. It is used to compensate for effects that impede accurate control with load-current feedback. Figure 7
Shows schematically the control device. This control device is provided with an operator control part 89, which inputs commands and various operating parameters for the purpose described below. As shown in FIG. 7, typical commands are "start", "run", "stop", and "emergency stop". These commands are considered convenient for producing different desired web tensions. Only the modes that result from the "run" command, which is normally issued automatically at the end of the starting sequence, are described in detail. The control unit transmits parameters and commands from the user to the processing circuit 90. The processing circuit 90 takes the form of a microprocessor, suitable memory, and peripherals. It also determines the required torque level from the parameters entered by the user and the input values of the various detectors described below.
For conceptual understanding, the brake current controller 92 is shown in a separate block, but is typically implemented in the same microprocessor that performs the torque calculation process 90.
The brake current controller 92 is intended to control the current driven by the synchronous rectifier 68 via the ballast resistor R1. According to the invention, this control can be performed, for example, by the current detector 9
4 based on the feedback of the current indication signal from 4. As described above, the brake current controller 92 can be, for example, a variable impedance, and the variable impedance is controlled in response to the feedback signal and the torque command from the torque calculation circuit 90. However, in the most common example, the brake / generator load current is controlled by changing the duty cycle of synchronous rectification according to the load-current command L. This load current command L is usually generated by the same microprocessor and other circuits that calculate the required torque. FIG. 8 shows a method for calculating an appropriate load-current command L. The load-current command L originates from the error signal E in any of the conventional ways used for this purpose. The calculations may be done in a simple proportional relationship, or other linear transformation functions such as proportional + integral + derivative functions may be applied, or conceptually more sophisticated processing may be performed. In any case, the error signal E means the difference between the target generated current or torque and the measured generated current or torque. Block 96 represents this process. To emphasize the essence of the current feedback of the controller, FIG. 8 shows a subtraction process 98 for subtracting the output i of the current detector 94 from the target current i _b to generate the error signal E. As shown in FIG. 8, the target current i _b is calculated in step 100 from the target brake torque τ _B. The exact equivalent current feedback action is performed by applying the inverse of the function calculated in step 100 to the current detector output i and subtracting the result from τ _b to obtain the error value E.
This will be different from the error value E obtained with the illustrated method, but will be proportional to the error value E obtained with the illustrated method. In some embodiments of the invention, it is sufficient to multiply τ _b by a proportional constant and simply calculate the target braking current i _b from the target braking torque. However, this method does not consider the effect of magnetic circuit saturation. This magnetic circuit saturation creates a non-linear relationship between current and torque. Also, this method does not consider the uncertainty in the relationship between current and torque. This uncertainty is due to changes in temperature,
It is caused by the usual variability in the properties of the brake material, its dimensions, and to a certain extent aging effects. All of these effects tend to cause a deviation of the air gap field magnetic flux density from a target designed value, and this deviation results in the torque-current proportionality not being established. To compensate for these factors, in some embodiments of the invention, a load cell may be used between the generator frame and the roll stand arm and used as an indicator of braking torque. Many factors may actually need to filter or average such measurements. Therefore, they alone do not lend themselves to a sufficiently fast response.
In order to solve this problem, the sample torque value can be stored in a check table together with the measured values taken at the same time, and this check table can be used to more accurately target the target brake current i _b . Convert the torque τ _b , or
Alternatively, although not shown in FIG. 8, the detection (sense) obtained by subtracting from the target brake torque τ _b
d) The error current E can be obtained by converting the detected current into the torque value τ. However, the invention proposes to use a simpler method of correcting the linearity and lack of reproducibility of the current-torque relationship. In particular, this correction is based on the measurement of magnetic flux density. FIG. 9 shows a typical reduction in generator torque due to the demagnetization effect of the cross-magnetization armature reaction, which is known to those skilled in the art. The band of the uncertainty 101 of the torque-current relationship due to temperature, manufacturing error, and temporal change in air gap magnetic flux density is shown. The uncertainty band resulting from the torque decrease with respect to the armature current and the deviation from the conceptually constant air gap magnetic flux density characteristic is shown in FIG.
Is shown in The deviation from the ideal value of the armature current due to armature reaction, temperature, manufacturing error, and aging can be determined from knowledge of the magnetic flux density B of the air gap. The magnetic flux density of the air gap is set by the detection winding set in the iron core slot of the armature (sense winding).
set) or by other means such as a Hall effect detector mounted on the surface of the armature core at the interface of the air gap. For example, a number of small unloaded sensing windings wound in one or more armature phases-or even a single winding-the product of magnetic flux density and angular velocity. Generates an output voltage proportional to. Therefore, dividing the generated voltage output V by the angular velocity ω of the brake generator produces a value proportional to the magnetic flux density. When this value is multiplied by the measured armature current, a value proportional to the brake torque is obtained. Thus, even if the relationship between torque and current is typically non-linear or drifts, torque readings that do not have these drawbacks can be obtained inexpensively. For this reason, FIG. 8 shows the torque-to-current conversion block 100, and this torque-to-current conversion block 100 shows the angular velocity ω of the brake-generator.
And the output voltage V of the magnetic flux detection winding. Signal lines 102 and 104 in FIG. 7 represent these inputs. Magnetic Flux Density If the air gap magnetic flux density is obtained using a non-velocity detector such as a Hall effect detector that provides an analog voltage V ', block 10 shown in FIG.
0'is used and no angular velocity input is required. The calculation of the target braking torque τ _b begins with the determination of the target tension force T _T. This is an input from a normal user, as indicated by the explanation "tension" in FIG. However, in many cases the more favorable known parameter is tension per unit width rather than tension. Actually,
The input may take the form of a web material name rather than an explicit number, which is converted to a tension value per unit width based on a pre-populated database. Block 106 of FIG. 8 represents a method of calculating the target tension T _T from such parameters entered by the operator and the roll width W. Desired web tension T
_{From T} , in order to determine the target value of the roll torque τ _T that the web should exert on the roll and vice versa, block 1
The desired tension is simply multiplied by the roll radius R, as shown at 08. The roll radius is detected directly with ultrasonic waves, optical detectors or feeler rollers. (The roll radius R must be measured at the point where the web leaves the roll to avoid inaccuracies that could otherwise be caused by roll eccentricity.) However, what is needed is FIG. As shown, drive roll 110, web 1
It has a nip roll 112 driving 13 and a sensor of the type such as an angle-position encoder provided on one of these rolls, which sensor is already provided to provide a web speed indication for another purpose. There is something. Therefore, the radius value R is determined by simply dividing the resulting velocity value by the angular velocity of the brake, as shown in block 114. The roll may be somewhat eccentric. As a result, the change in the roll radius that occurs with each rotation is superimposed on the change in the long period of the roll radius that occurs due to the web rewinding. Since these fluctuations significantly affect the torque, it is important to measure the radius accurately.
The electronics used to calculate the radius are usually faster than necessary to calculate in real time, but measurements of web speed and roll angular velocity, for example due to web vibration and drive roll slippage. Has a small error. For this reason, some embodiments of the present invention record the eccentricity observed in previous rotations and provide it forward (with appropriate compensation for intervening web removal) in real time. Get a more accurate estimate of the radius. As a realization of this method, FIG. 7 shows the entry of the "web thickness" to be used for web removal compensation. However, FIG. 8 does not explicitly show the “feedforward” confirmation at block 114. Regardless of how the radius R is determined, the output τ _{T of the} operation represented by block 108
Displays the roll torque that produces the desired web tension. In some applications, the roll torque-the product of web tension and roll radius-may not be the same value as the brake torque. In particular, the roll torque is the sum of the brake torque and the inertia torque, and is τ _T = τ _b + Jα, where J is the roll inertia moment and α is the angular acceleration. Angular acceleration is the result of an increase in roll angular velocity as the roll radius increases, as long as the web velocity remains constant and large, but this angular acceleration is usually negligible. However, for example, the influence on the inertia torque caused by the eccentricity of the roll is significant. Assuming the web velocity is exactly constant, the roll should undergo angular acceleration and deceleration if there is some eccentricity. Without proper control this is not a problem, the accelerations and decelerations are less than the accelerations and decelerations that the roll eccentricity produces in the absence of large roll inertia, and web tension and possibly web speed is a problem. The result is a periodic vibration. Therefore, if it is necessary to maintain a constant value despite the tensioned eccentricity, it must be compensated, which is why the operation represented by block 115 is provided. The operation of this block subtracts the inertia torque Jα from the target roll torque τ _T to give the target brake torque τ _b . The inertia torque J is calculated by differentiating the angular velocity ω immediately in front of it.
The angular acceleration α required to calculate α is obtained. The moment of inertia J is a function of R, and J (R) = (1/2) πρW (R ⁴ −Rc ⁴ ), where ρ is mass density, W is roll width, and Rc is roll core rod. Is the radius of. The operator usually inputs the roll width W clearly and also inputs the initial mass Mg, the initial diameter Di, the half initial radius Ri and the core rod diameter Dc, and the half radius Rc of the core rod. To input the density ρ. The initial mass Mg is given by Mg = πρW (Ri ² −Rc ² ), From this equation, the mass density is easily determined, Becomes Blocks 117 and 118 perform these calculations. In practice, omitting Rc in the previous equation causes a small error, and this practical equation is adopted to eliminate the need for the operator to input the diameter of the core rod. This completes the description of the response operation to the operation command. The response to other commands is almost the same. The main difference is
The use of a numerical value of the target tension T _T , which has a time-varying characteristic, as opposed to the tension explicitly entered by the operator. However, during a stop or emergency stop operation, the regenerative braking torque obtained at roll angular velocities below the minimum operating speed is less than the torque required to stop completely without excessive coasting or curving of the web material. . In generator mode operation, the brake output decays non-uniformly with speed, and the roll speed decays exponentially in the absence of web tension that can occur in the event of an emergency stop due to web breakage. Will be seen. For example, the illustrated roll of 80 inches (about 203.2 cm) wide and 60 inches (about 152.4 cm) diameter will reach zero speed in a web break emergency stop, usually in about 10 seconds, without web tension. In the worst case where a stop command is issued when is at operating speed and the roll diameter is perfect,
The web material will bend about 58 feet. However, some installations require stronger braking in response to a stop or emergency stop command. The mode selector switch 118 (FIG. 7) and the power supply 120 are “plug brakes”.
g) ”. In this plug brake, the brake acts as a motor against the rotation of the roll, and the rectifier acts as an inverter in synchronism with the brake to generate a brake torque even at an extremely low roll speed. In the example described above, when applying the plug brake torque, the exponential end of the roll velocity decay curve was truncated and only 14 feet of material was bent, resulting in only a small amount of bending. It can be stopped in 2.7 seconds. From the above, it is clear that the use of the device of the present invention increases the possibility of taking advantage of the dynamic braking over a wide area around the roll stand. Moreover, by using current feedback to control the brake, it is possible to obtain an accurate and responsive tension control without using the expensive method of measuring web tension directly. Therefore, it is obvious that the present invention brings about remarkable effects.

[Brief description of drawings]

FIG. 1 is a side view of a roll stand provided with a brake according to the present invention.

FIG. 2 is a front view showing the roll shown in FIG. 1 with a stand base and an actuator removed.

FIG. 3 is a sectional view of the brake positioned on the core rod of the roll stand according to the embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of the brake taken along line 4-4 of FIG.

FIG. 5 is a sectional view showing another embodiment of the present invention similar to FIG.

FIG. 6 is a schematic diagram of a load circuit of a generator.

7 is a block diagram of a controller used to control the brake shown in FIGS.

FIG. 8 is a block diagram showing a calculation performed by a processing circuit of the control device.

FIG. 9 is a graph showing the relationship between generator torque and armature current.

FIG. 10 is a graph showing the relationship between the magnetic flux density in the generator air gap and the armature current.

FIG. 11 is a diagram showing another embodiment of the operation for determining the target generator current shown in FIG.

[Explanation of symbols]

10 Roll Stand 11 Base 12 Roll Stand Arm 14 Actuator 16 Core Rod 18 Core Chuck 22 Roll 24 Floor 26 Brake 28 Projection 30 Anti-rotation Arm 32
Pin 36 Rotor 38 Hollow shaft 40 Disc 44 Permanent magnet 52 Stator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H02P 15/00 H02P 15/00 H (71) Applicant 595154568 359 North Road, Bedford, Massachusetts 01730, United States of America

Claims (25)

[Claims] 1. A roll stand for holding rolls, a base, a roll stand arm mounted on the base and having a bearing block for the arm, and a roll stand arm terminating in a core connector of the roll and comprising: A core rod supported by a roll stand arm in the bearing block; and a permanent magnet-type generator, wherein the permanent magnet-type generator includes a stator having a generator bearing block, and a permanent magnet-type generator in the generator bearing block. It has a supported hollow rotor shaft, supports the stator with the rotor shaft, receives the core rod, is fixed to the core rod, and extends in the axial direction to support the generator with the core rod. A roll stand comprising a rotor forming a recess. 2. The roll stand according to claim 1, wherein the rotor has a permanent magnet that generates a time-varying magnetic field in the stator as the rotor rotates, and the stator rotates the rotor. A stand for a roll having an armature winding arranged in a time-varying magnetic field generated by. 3. The roll stand according to claim 2, wherein the permanent magnets are arranged radially outside the armature winding. 4. The roll stand according to claim 1, wherein the core connector of the roll includes a core chuck. 5. A roll stand for holding rolls, comprising: a base; a roll stand arm mounted on the base and having a bearing block for the arm; A core rod supported by the roll stand arm in a bearing block; and a permanent magnet generator axially arranged apart from the bearing block of the arm, wherein the permanent magnet generator is attached to the roll stand arm. A roll stand comprising: a stator that is mounted and supported; and a rotor having a rotor shaft that is rigidly fixed to the core rod in the axial direction so as to be supported by the core rod. 6. The roll stand according to claim 5, wherein the rotor has a permanent magnet that generates a time-varying magnetic field in the stator as the rotor rotates, and the stator rotates the rotor. A stand for a roll having an armature winding arranged in a time-varying magnetic field generated by. 7. The roll stand according to claim 6, wherein the permanent magnets are arranged radially outside the armature winding. 8. The roll stand according to claim 5, wherein the core connecting member of the roll includes a core chuck. 9. A roll stand according to claim 5, wherein said rotor shaft receives said core rod and is fixed to said core rod in an axial direction to provide a connector having axial rigidity. A roll stand characterized by forming an extending recess. 10. A roll stand used in a roll stand for rotatably supporting a roll of web material and mounted on a roll stand in the form of a generator driven by rotation of a roll rotatably mounted on said roll stand. A control device for controlling a brake, which is connected so as to be driven by a generator and which is variable by applying a load control signal, and a current which the generator transmits to the load is detected and displayed. Current-a detector that produces a detector output, a combination of the angular velocity of the generator and the radius of the roll, a combination of the angular velocity of the generator and the web speed, and another that displays the web velocity, the roll radius and the roll radius. A detector circuit for detecting at least one of the combinations with the detector outputs of the An error amount determination circuit that determines the target brake torque from the output of the generator and calculates an error value proportional to the difference between the target brake torque and the brake torque displayed by the output of the current detector, and a response to the error value. And a load control device that controls the load in a direction to reduce the error value. 11. The control device according to claim 10, wherein the generator has an armature winding through which a load current flows, and the detector circuit has a magnetic flux density detector. The magnetic flux density affected by the child winding is measured, and the error determination circuit obtains a value proportional to the current detector output by dividing the target brake torque by the magnetic flux density measured by the magnetic flux density detector. A controller that calculates an error numerical value by comparing it with a numerical value that is proportional to the calculated numerical value. 12. The control device according to claim 10, wherein the generator has an armature winding through which a load current flows, and the another detector measures a magnetic flux density generated by the armature winding. And a value proportional to the target brake torque, and a value proportional to the result of multiplying the magnetic flux density measured by the magnetic flux density detector by the current detector output. A control device characterized by calculating the error numerical value by comparing with. 13. The control device according to claim 10, wherein the error determination circuit determines a roll radius value from the other detector and is a target proportional to a product of a target tension and a roll radius value. A control device characterized in that a target brake torque is determined by calculating a torque value. 14. The control device according to claim 13, wherein the another detector detects a web speed and a generator angular velocity, and the error quantifying circuit detects the detected angular velocity with respect to the detected angular velocity. A controller for determining a roll radius value by calculating a numerical value proportional to a ratio of web speeds. 15. The control device according to claim 10, wherein the error amount determining circuit determines an inertia torque of a roll from an output of the another detector, and calculates a difference between the target roll torque and the inertia torque. A control device characterized in that a target brake torque is determined by calculation. 16. The control device according to claim 10, wherein the other detector detects a web speed and a generator angular speed,
Then, the error determination circuit determines the roll radius value by performing a numerical calculation proportional to the detected web speed with respect to the detected generator angular velocity, and determines the angular radius of the acceleration by differentiating the detected generator angular velocity. Decide the number,
Then, the control device is characterized in that the inertial torque of the roll is determined from the roll radius and the value of the determined angular acceleration. 17. A bearing cartridge for mounting on a roll stand for mounting on a roll stand arm body to form an arm bearing block, and a bearing cartridge terminating in a roll core connector. A core rod that is supported inside and that is supported by the roll stand arm when the bearing cartridge is mounted on the roll stand arm; and a permanent magnet generator that is axially spaced from the arm bearing block. When the bearing cartridge is mounted on a roll stand arm, the permanent magnet generator includes a stator mounted on the bearing cartridge by the roll stand arm, and a core rod supported by the core rod. A rotor having a rotor shaft that is rigidly fixed in the axial direction. Brake assembly to be attached to the Le stand. 18. A brake assembly to be mounted on a roll stand according to claim 17, wherein the rotor has a permanent magnet that generates a time-varying field in the stator as the rotor rotates, Has a armature winding arranged in a time-varying field generated by the rotation of the rotor, and is mounted on a roll stand. 19. A brake assembly to be mounted on the roll stand according to claim 18, wherein the permanent magnet is arranged axially outward of the armature winding. Brake assembly to install. 20. A brake assembly for mounting to a roll stand according to claim 17, wherein the core connecting member of the roll comprises a core chuck. 21. A brake assembly to be mounted on a roll stand according to claim 17, wherein said rotor shaft is formed with a recess extending in the axial direction for receiving said core rod, and fixed to said recess. A brake assembly to be attached to a roll stand, wherein the brake assembly is provided with a rigid connector. 22. A generator used in a form extended from a shaft, the stator having a bearing block of a permanent magnet type generator, and a hollow rotor shaft supported by the bearing block of the permanent magnet type generator. And a rotor forming an axially extending recess formed to receive a shaft supported by the rotor shaft and fixed to support the generator. 23. The generator according to claim 22, wherein the rotor includes a permanent magnet that generates a time-varying magnetic field in the stator as the rotor rotates, and the stator includes a permanent magnet of the rotor. A generator having armature windings arranged in a time-varying field generated by rotation. 24. The generator according to claim 23, wherein the permanent magnet is arranged axially outward of the armature winding. 25. A method of achieving a target torque of a generator or a motor comprising an armature winding that conducts an armature current, the method comprising: measuring a magnetic flux density generated by the armature winding; Measuring the current, calculating an error value proportional to the difference between the target torque and a numerical value proportional to the product of the measured magnetic flux density and the measured armature current, and reducing the error value. Controlling the armature current in the method.