JP7153312B2 - Conveyor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conveyor suitable for conveying chips and the like produced by metal cutting.

As shown in Patent Document 1, Non-Patent Document 1, and FIG. By rotating the tray 2 at a low speed, the chips 5 put into the tray 2 are separated into solid and liquid, conveyed in a predetermined direction within the tray 2, and discharged to a discharge duct 6 connected to the outlet of the tray 2. The cutting fluid 7 introduced into the tray 2 together with the chips 5 drops from the tray 2 by gravity during transportation, is separated from the chips, and is collected in a cutting fluid tank 8 provided below.

Spiral conveyors with such a structure can smoothly convey chips of various shapes, sizes, and materials, from highly expanded long-chain continuous chips to needle-like fine chips, without entangling them. It is simple and can be manufactured and provided at low cost, it is possible to transport chips over a long distance in a machining system that connects many types of machine tools, and it is possible to efficiently separate and collect cutting fluid adhering to chips. It is used in many machine tools due to its capability.

Japanese Patent Application Laid-Open No. 2018-001400

http://www.to-hatsu.co.jp/products/sc_built.html

In conventional spiral conveyors , a motor is generally rotated at a constant speed to drive the conveying spiral (normal operation). As an example, a 1500 RPM (50 Hz) or 1800 RPM (60 Hz) motor is reduced to 50 RPM (50 Hz) or 60 RPM (60 Hz) by a reduction gear with a reduction ratio of 1/30 to drive the conveying spiral . However, since normal operation is performed even when no chips are input or when the amount of input is small, power consumption is wasted, and vibration and noise are always generated during normal operation.

In addition, although the spiral conveyor is structurally resistant to clogging, clogging may occur depending on the amount and shape of chips to be fed, or may occur due to the inclusion of foreign matter. Continuing normal operation even when such a transport abnormality occurs may damage the output shaft of the motor or the bearing.

As a solution to this problem, the current value flowing through the motor is measured using a thermal relay or shock relay, and when overcurrent (overload) is detected, an alarm is sounded and the motor is automatically stopped. However, thermal relays are used to prevent motor burnout, and are slow to react, and may damage the drive system before it stops. Although shock relays are quick to respond, they are extremely expensive and practically costly difficult to use in spiral conveyors. In addition, since the control to detect overcurrent and stop the motor does not work during normal operation, power consumption is wasted due to normal operation even when there is no chip input or when the input amount is small. The aforementioned problems of vibration and noise during normal operation cannot be resolved.

Chips discharged from machine tools, especially multifunction machines such as MC (machining center) and TC (tapping center), have various shapes, weights, and volumes.・Conveyance force (thrust force) required for the spiral conveyor, which plays the role of discharging, varies from 0 to infinity depending on the properties of chips, the amount of input, and whether the conveying path is flat or inclined. It varies greatly, and changes from moment to moment. Therefore, it is extremely difficult to directly detect the thrust force to be controlled (for example, by using an axial force detector installed between the conveying spiral 3 and the fixed part) to set the control target value. impractical.

Therefore, the inventor of the present invention has devised a method of detecting the motor power that changes according to the load during transportation, calculating the motor output torque and spiral torque from this change, and further calculating the transportation force based on the screw principle. In other words, by indirectly estimating the thrust force, which is the target of control, it is possible to accurately and in real time control even when the load varies in various ways, and has completed the present invention.

That is, in view of the above background, the problem to be solved by the present invention is that it is possible to improve the power saving of the conveyor and the vibration damping / noise reduction effect, and when clogging of chips and contamination of foreign matter occurs To provide an improved conveyor capable of smoothly coping with even

In order to solve this problem, the present invention according to claim 1 has a motor, a conveying body that is driven by the motor to convey an object to be conveyed in a predetermined direction, and a control device that controls the rotation of the motor. In the conveyor, the control device includes a frequency inverter connected to a motor, a power value computing means for determining a current effective power value based on the power value output from the frequency inverter to the motor, and a power value computing means. power value comparing means for comparing the effective power value obtained with the target power value with a predetermined target power value; a control signal transmission means for outputting a deceleration control signal to the frequency inverter, and outputting an acceleration control signal for increasing the motor rotation speed to the frequency inverter when the effective power value is lower than the target power value. Characterized by

According to a second aspect of the present invention, there is provided the conveyor according to the first aspect, wherein the control device further comprises the current motor torque or Torque computing means for computing spiral torque; Torque comparing means for comparing the motor torque or spiral torque determined by the torque computing means with a predetermined maximum torque value; A stop control signal for stopping rotation of the motor is output to the frequency inverter when it is determined that the motor torque or spiral torque exceeds the maximum torque.

The present invention according to claim 3 is the conveyor according to claim 1 or 2, wherein the power value comparison means further compares the effective power value obtained by the power value calculation means with a predetermined power upper limit value. and, when the effective power value exceeds the power upper limit value, the control signal transmitting means outputs a stop control signal for stopping the rotation of the motor to the frequency inverter based on the determination result .

According to the first aspect of the present invention, the current effective power value obtained based on the power value output from the frequency inverter to the motor is compared with the target power value calculated based on the current motor rotation speed. , the number of revolutions of the motor is controlled based on the judgment result, so when there is no chips or only a small amount of chips, the motor is decelerated to eliminate wasteful power consumption and improve vibration damping and noise reduction effects. Also, when a large amount of chips are temporarily thrown in, the speed of the motor can be increased to enable smooth conveyance.

According to the second aspect of the present invention, control is performed to stop the motor when the current transfer torque exceeds a predetermined maximum value. As a result, damage to the motor output shaft and bearings can be prevented.

According to the third aspect of the present invention, control is performed to stop the motor when the current effective power value exceeds the predetermined power upper limit value . By stopping, damage to the motor output shaft and bearings can be prevented.

It is a front view which shows the basic structure of a spiral conveyor. 1 is a top view of essential parts of a spiral conveyor according to an embodiment of the present invention; FIG. It is a flow for controlling the operation of this spiral conveyor. FIG. 4 is a specific control explanatory diagram in this spiral conveyor;

A spiral conveyor according to one embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG. This spiral conveyor 10 has the same basic structure as the spiral conveyor 1 of FIG. 4) is provided with a frequency inverter 17 and a controller 18 for automatic control of the rotation speed and rotation/stop.

More specifically, an output shaft 13 of a motor 12 equipped with a speed reducer 11 is welded to a drive sleeve 16 via a knuckle 14 to the starting end of a conveying spiral 15 (indicated by reference numeral 3 in FIG. 1). , and rotates the conveying spiral 15 at a speed that is substantially the same as the rotational speed (after deceleration) of the motor output shaft 13 to remove chips (not shown in FIG. 2, indicated by reference numeral 5 in FIG. 1) in the tray 2 ) is conveyed to the right in the figure.

When the chips 5 are conveyed by the spiral conveyor 10, the magnitude of the load torque acting on the motor 12 or the conveying spiral 15 varies depending on the weight and size of the thrown chips, the state of use (horizontal conveying, inclined conveying), etc. It changes moment by moment. Therefore, it is not practical to set a uniform target torque value (or thrust value).

Therefore, in the spiral conveyor 10, attention is paid to the effective power value Wa calculated based on the power value (detected power value Wm) output from the frequency inverter 17 connected to the motor 12. Wa is compared with the target power value Wp, and based on the result, the output frequency to the motor 12 is controlled to increase/decrease or stop. As is well known, the frequency inverter 17 includes phase current detectors 171 that detect the three-phase motor currents U, V, and W flowing through the motor 12. Based on the detection results, etc., the frequency converter circuit 172 detects appropriate currents. A frequency is determined and output to the motor 12 . 3, an arithmetic circuit 182 for executing S3, S5 to S7 in the flow of FIG. 3, and S8, S8 in the flow of FIG. Control for executing S10, S12 to S15 in the flow of FIG. and a signal output circuit 184 .

Hereinafter, description will be made with reference to the control flow of FIG. The detected power value Wm (W) output from the frequency inverter 17 includes a power value (idling power value Wl) that is required even when there are no chips 5 (during idling). The effective power value Wa is obtained in S3 from the power value Wl during idle rotation stored in , and the detected power value Wm obtained in S2 (Wa=Wm-Wl).

Also, from the predetermined frequency data f (generally 50 Hz or 60 Hz) stored in S4, in S5, the motor rotation speed Nm (rpm) is calculated by the arithmetic expression: Nm = 120 x f / p (p is the number of poles of the motor). is obtained, and based on the effective power value Wa obtained in S3 and the motor rotation speed Nm obtained in S5, in S6, the motor torque Tm ( kgf·cm), and based on the motor torque Tm obtained in S6, the spiral torque Ts is obtained in S7 by the arithmetic expression: Ts=β×Tm (reduction ratio: 1/β). Then, in S8, the spiral torque Ts acquired in S7 is compared with a preset spiral torque maximum value Tsmax to determine whether Ts>Tsmax.

When Ts>Tsmax (S8: Yes), there is a possibility that the feeding spiral 15 is clogged with the chips 5 because the amount of chips 5 input is excessive or long chips 5 are entangled in the conveying spiral 15. Therefore, in S10, the control device 18 sends a control signal to the frequency inverter 17 to make the output frequency zero, and the motor 12 is forcibly stopped.

Also, in S9, the effective power value Wa acquired in S3 is compared with a power upper limit Wmax, which will be described later with reference to FIG. 4, to determine whether Wa>Wmax. When Wa>Wmax (S9: Yes), similarly to the case of Ts>Tsmax, the amount of chips 5 input is excessive, or long chips 5 are entangled in the conveying spiral 15, causing the conveying spiral 15 to become entangled. Since chips 5 may be clogged, in S10, the control device 18 sends a control signal to the frequency inverter 17 to set the output frequency to zero, and the motor 12 is forcibly stopped.

When Ts≤Tsmax (S8: No) and Wa≤Wmax (S9: No), the process proceeds to S11, where the effective power value Wa is compared with a preset target power value (Wp). When Wa>Wp, it means that the current spiral torque Ts is insufficient in relation to the amount of chips 5 and the conveying speed. The spiral torque Ts is calculated, and in S13, a control signal is sent to the frequency inverter 17 to reduce the frequency so that the appropriate spiral torque Ts is obtained, and the motor 12 is controlled to decelerate. When Wa<Wp, it means that the current spiral torque Ts is excessive in relation to the amount of chips 5 and the conveying speed. A torque Ts is calculated, and in S15, a control signal for decreasing the frequency is output to the frequency inverter 17 so as to obtain the proper spiral torque Ts, and the motor 12 is speed-up controlled.

Although not shown, when Wa=Wp, it means that an appropriate spiral torque Ts is obtained at the current motor rotation speed Nm. to maintain

The control performed in S8 to S15 will be described more specifically with reference to FIG. FIG. 4 shows a power value line that changes in correlation with spiral torque Ts (kgf·cm) and spiral rotation speed Ns. Since the spiral rotation speed Ns is proportional to the motor rotation speed Nm (rpm) (Ns=Nm×1/β)), the target power value Wp line shown in FIG. The proper value of the spiral torque Ts is specified by and. As described above, the effective power value Wa can be obtained by subtracting the idling power value Wl from the power value Wm detected by the frequency inverter 17 as Wa=Wm−Wl (Wl=100 W in this example).

FIG. 4 shows proper values of the spiral torque Ts with respect to the spiral rotational speed Ns when the effective power values Wa=300W and 400W. The larger the amount of chips thrown into the spiral conveyor 10, the larger the effective power value Wa. However, in order to avoid overloading the motor 12, here, Wa=400 W is set as the power upper limit value Wmax, and this power upper limit value A power value of 300 W (target power value Wp) corresponding to 75% of Wmax=400 W was set as a control target. The spiral rotation speed Ns is controlled within the range of 32 to 60 rpm, and the spiral torque maximum value Tsmax is 913 kgf·cm indicated by the target power value Wp line when the spiral rotation speed Ns=32 rpm.

For example, the detected power value Wm=450W (therefore, the effective power value Wa=450−100=350W) when the spiral rotation speed Ns=50 rpm, and the spiral torque Ts obtained in S7 of the control flow shown in FIG. =682 kgf·cm (point P1). This spiral torque Ts=682 kgf·cm is larger than the target power value Wp at the spiral rotation speed Ns=50 rpm shown in FIG. It turns out that That is, in this case, the spiral rotation speed Ns is larger than necessary with respect to the amount of chips to be thrown, etc., and the effective power value Wa exceeds the target power value Wp (Wa>Wp).

Therefore, in this case, the control device 18 determines Wa>Wp in S11 of the control flow of FIG. 3, and refers to the target power value Wp line in FIG. The spiral rotation speed Ns at the point (P2) matching the Wp line is found to be Ns=42 rpm, and in S13, the output frequency of the frequency inverter 17 is reduced so that the spiral rotation speed Ns=42 rpm is obtained. A control signal is transmitted to perform deceleration control so as to reduce the spiral rotation speed Ns (therefore, the motor rotation speed Nm).

As another example, for example, when the spiral rotation speed Ns=50 rpm, the detected power value Wm=350 W (therefore, the effective power value Wa=350-100=250 W), and in S7 of the control flow shown in FIG. Suppose that the obtained spiral torque Ts is Ts=505 kgf·cm (point Q1). This spiral torque Ts=505 kgf·cm is smaller than the target power value Wp at the spiral rotation speed Ns=50 rpm shown in FIG. It turns out that That is, in this case, the spiral rotation speed Ns is insufficient for the amount of the chips 5 thrown in, and the effective power value Wa is lower than the target power value Wp (Wa<Wp).

Therefore, in this case, the control device 18 determines Wa<Wp in S11 of the control flow of FIG. The spiral rotation speed Ns at the point (Q2) matching the Wp line is found to be Ns=58 rpm, and in S15, the output frequency of the frequency inverter 17 is increased so that the spiral rotation speed Ns=58 rpm is obtained. A control signal is transmitted to perform speed-up control to increase the spiral rotation speed Ns (therefore, the motor rotation speed Nm).

As described above, when the spiral torque Ts acquired in S7 of the control flow shown in FIG. ), or when the effective power value Wa obtained in S2 exceeds the power upper limit value Wmax shown in FIG. , S10, a control signal is given to the frequency inverter 17 so as to set the output frequency to zero, and the motor 12 is forcibly stopped.

Although the present invention has been described in detail above based on the illustrated embodiments, the present invention is not limited to these, and various modifications and variations can be made within the scope of the invention determined based on the description of the claims. It can be changed and implemented.

For example, in the illustrated embodiment, the power upper limit value Wmax line and the target power value Wp line in FIG. However, the spiral rotation speed Ns and the spiral torque Ts are proportional to the motor rotation speed Nm and the motor torque Tm, respectively. In addition to setting the power upper limit value Wmax line and the target power value Wp line in FIG. 4, the motor torque upper limit value Tmmax may be set and used for control.

Further, the spiral conveyor 10 of the illustrated embodiment is of a type having a hollow conveying spiral 15 without a central axis, but the present invention is also applicable to a spiral conveyer of a type having a conveying spiral 16 with a central axis. It is possible, and it is also applicable to conveyors other than spiral conveyors (so-called chip conveyors, etc.). In the spiral conveyor 1 shown in FIG. 1, a discharge duct 6 is connected to the outlet of the tray 2 to transport chips obliquely upward. The present invention is applicable.

In the illustrated embodiment, one spiral conveyor 10 is targeted for control. The present invention can also be applied to a case in which one or more conveyors for carrying out and one or more conveyors for conveying chips and cutting fluid while separating them are installed. In this case, since the specifications (power value, reduction ratio, etc.) of the motor 12 used for each conveyor are different, the frequency inverter 17 needs to be installed as a set for each motor 12. It is preferable to collectively control a plurality of frequency inverters 17 by accumulating data of control results (S10, S13, S15 in the flow of FIG. 3) in 18 and analyzing this as big data.

1 Spiral Conveyor 2 Tray 3 Conveying Spiral 4 Motor with Reduction Gear 5 Chips 6 Discharge Duct 7 Cutting Fluid 8 Cutting Fluid Tank 10 Spiral Conveyor 11 Reduction Gear 12 Motor 13 Motor Output Shaft 14 Knuckle 15 Conveying Spiral (Conveyor)
16 drive sleeve 17 frequency inverter 171 phase current detector 172 frequency conversion circuit 18 control device 181 input circuit 182 arithmetic circuit (power value arithmetic means, torque arithmetic means)
183 decision circuit (power value comparison means, torque comparison means)
184 control signal output circuit (control signal transmission means)

Claims (3)

A conveyor having a motor, a transport body that is driven by the motor to transport objects to be transported in a predetermined direction, and a control device that controls the rotation of the motor, wherein the control device is a frequency inverter connected to the motor. a power value computing means for determining the current effective power value based on the power value output from the frequency inverter to the motor; and a power value for comparing the effective power value determined by the power value computing means with a predetermined target power value. When the effective power value exceeds the target power value based on the comparison means and the determination result by the power value comparison means, a deceleration control signal for decreasing the motor rotation speed is output to the frequency inverter so that the effective power value reaches the target value. and control signal transmission means for outputting an acceleration control signal to the frequency inverter for increasing the motor rotation speed when the power value falls below the power value. The control device further includes a torque calculation means for calculating a current transfer torque based on the effective power value obtained by the power value calculation means and the current motor rotation speed, and a transfer torque calculated by the torque calculation means in advance. a torque comparison means for comparing with a predetermined maximum torque value, and the control signal transmission means performs stop control for stopping rotation of the motor when the torque comparison means determines that the transfer torque exceeds the maximum torque. 2. Conveyor according to claim 1, characterized in that it outputs the signal to a frequency inverter. The power value comparing means further compares the effective power value obtained by the power value computing means with a predetermined power upper limit value, and if the effective power value exceeds the power upper limit value, the determination result is 3. The conveyor according to claim 1 , wherein said control signal transmitting means outputs a stop control signal for stopping rotation of said motor to said frequency inverter.

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