JP2776899B2 - Transfer device using linear motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transport device that transports an object using a linear motor.

(Conventional technology) Recently, in a production line of a production factory, it is desired to quickly and quietly convey an object to be conveyed from the viewpoint of improving production efficiency or improving a working environment. Such a transfer device is disclosed in, for example,
As disclosed in Japanese Patent No. 61689, there is known an apparatus using a linear motor including a linear motor coil and a reaction member. As shown in FIG. 10, a transfer device using this linear motor has one of linear motor coils b, b,... And a reaction member c (in the figure, linear motor coils b, b, ..) As a stator along a roller conveyor e composed of a plurality of rollers d, d,..., And the other (reaction member c in the figure) as a mover via a mounting member g to a pallet f to be conveyed. And attach these linear motor coils b, b, ...
The pallet f and the articles placed thereon are conveyed via the mover (reaction member c) by the thrust F generated on the mover (reaction member c) by the electromagnetic action between the pallet f and the reaction member c. It is configured as follows.

Incidentally, the gap δ between the linear motor coil b and the reaction member c changes due to variations or differences in the weight of the pallet f and the articles placed thereon. Therefore, conventionally, the gap δ
Is detected by gap detecting means such as a laser length measuring instrument,
On the basis of the detection result, the excitation amount of the linear motor coil b is controlled when the object is transferred between the next work stations so that the thrust F is constant regardless of the variation of the gap δ. is there.

(Problems to be Solved by the Invention) However, since the gap detecting means such as the laser length measuring device is expensive, there has been a problem that versatility is lacking in cost.

The present invention has been made in view of such a point, and a purpose thereof is, in particular, a case in which a gap δ between a linear motor coil b and a reaction member c has a transfer state when a transferred object is transferred, Is related to the weight of the object to be transported and the transport speed preset according to the weight and the actual rise acceleration during transport, and all three elements are preset or simple. Focusing on the fact that it can be easily detected by the detection means, by estimating the gap δ from these three factors and using it for control, while keeping costs down, the thrust is kept constant regardless of the gap variation. Thus, the operation control of the linear motor can be appropriately performed.

(Means for Solving the Problems) In order to achieve the above object, a solution of the invention according to claim 1 is to sequentially feed a conveyed object to each work station using a linear motor including a linear motor coil and a reaction member. A transfer device, comprising: acceleration detection means for detecting a rising acceleration during the transfer of a transferred object; a rising acceleration detected by the detecting means; a weight of the transferred object; and a transfer speed set in accordance with the weight. And a gap calculating means for calculating a gap between the linear motor coil and the reaction member from the above, and based on the gap determined by the calculating means and the weight of the transferred object, the transferred object is transferred between the next work stations. And control means for controlling the amount of excitation of the linear motor coil so as to obtain a predetermined thrust when being conveyed.

Here, in the invention of claim 2, the gap calculating means according to claim 1 maps the relationship between the rising acceleration at the time of transporting the transported object, the weight of the transported object, and the transport speed and gap according to the weight. It is assumed that a gap is obtained from the map.

(Operation) With the above configuration, according to the first and second aspects of the invention, when the transported object is sequentially fed to each work station by the linear motor, a rising acceleration when the transported object is transported between certain work stations is detected. The gap calculating means calculates and estimates the gap between the linear motor coil and the reaction member from the detected rising acceleration, the weight of the transferred object, and the transfer speed set in advance according to the weight. You. Then, when transporting the transported object between the next work stations, by the control means,
The excitation amount of the linear motor coil is controlled to obtain a predetermined thrust based on the gap and the weight of the transferred object obtained by the calculation means, whereby the thrust is maintained constant regardless of the variation in the gap, Transport becomes stable.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 1 to 3 show a case in which a transfer device A using a linear motor is applied to a vehicle assembly line as one embodiment of the present invention. In a state where the body B is mounted on the work station, it is transported between adjacent work stations within a predetermined time.
The pallet P is supported by a roller conveyor 3 composed of a number of rollers 2, 2,... Rotatably mounted on support members 1, 1 on both sides of the conveying line, and is conveyed while sliding on the roller conveyor 3. It is supposed to be.

Inside the two support members 1, 1, there are two stator rows 11, which are composed of a large number of linear motor coils 10, 10,... As a stator formed by winding an excitation coil around, for example, a comb-shaped iron core. 11
Are juxtaposed. On both sides of each stator row 11, two guide rails 12, 12 extending in the transport direction are arranged, and a plate member 13 is movably engaged with the guide rails 12, 12, and is arranged. In addition, a reaction member 14 as a mover formed by laminating, for example, iron and aluminum in a plate shape is integrally attached to the lower surface of the plate member 13. Therefore, the reaction member 14 is provided movably along the stator row 11 under the guide of the guide rail 12. In addition, guide rail 12
The engagement between the plate member 13 and the plate member 13 does not restrict the upward displacement of the plate member 13.

The plate member 13 is attached to the back surface of the pallet P via an attachment member 15. Thus, the reaction member 14 provided in each of the stator rows 11 has a thrust generated by the electromagnetic action between each of the stator rows 11 and each of the linear motor coils 10, so that each of the stator rows 11 has a thrust. Along the transport direction downstream (left side in FIG. 1),
Thereby, the pallet P on which the body B is placed is transported between adjacent work stations in a sequential manner within a predetermined time, and the linear motor coil 10 and the reaction member 14 A linear motor 23 is configured, and the linear motor 23 is provided at a ratio of one for each work station.

FIG. 4 shows a block configuration of a control unit for controlling the linear motor 23. In the figure, reference numeral 31 denotes a speed sensor comprising a pulse generator or the like for detecting the moving speed of the pallets P, that is, the transfer speed when the pallets P are transferred between adjacent work stations, and 32 denotes a linear motor for each work station. 23 is a station controller provided as a control means for controlling the operation of the linear motor 23 (specifically, the excitation of each linear motor coil 10).
A signal from a speed sensor 31 for detecting the moving speed of the pallet P between the corresponding work station and the work station on the downstream side (right side in the drawing) in the transport direction is input to the station controller 32. A line controller 33 controls the transfer of the pallets P over the entire transfer line. The line controller 33 and each station controller 32 are connected so that control / information signals can be transmitted and received.

Next, the calculation of the excitation amount serving as a database when the excitation control of the linear motor coil 10 is performed by each of the station controllers 33 will be described based on the control flow shown in FIG.

In FIG. 5, first, at step S1, the transport speed at the start of transport of the pallet P detected by the speed sensor 31 is differentiated to calculate the rising acceleration a of the let P. The step S1 and the speed sensor 31 constitute an acceleration detecting means 41 for detecting a rising acceleration a when the pallet P is transported.

Next, in step S2, a gap δ between the linear motor coil 10 and the reaction member 14 is calculated. The calculation of the gap δ uses a gap calculation map as shown in FIG. 6, and the rise acceleration a and the weight of the transferred object (the pallet P and the entire body B placed on the pallet P) are determined in step S1. Weight) W and the transport speed v are calculated as parameters. The map is created based on the results of an experiment on the correlation between the gap δ, the rising acceleration a, the weight W of the load, and the transfer speed v.
As can be seen from this map, the gap δ gradually decreases as the rising acceleration a increases when the weight W of the object to be transported and the transport speed v are equal, and as the weight W of the object to be transported decreases when the rising acceleration a is equal. (W1
<W2 <W3), and the higher the transport speed v (v11>v12> v1)
3, v21>v22>v23>,v31>v32> v33), and the gap δ has a large value. Note that the weight W of the transferred object is obtained from an information signal from the line controller 33, and the transfer speed v is set in advance according to the weight W. As described above, in step S2, the actual rise acceleration a, the weight W of the transferred object, and the transfer speed v during the transfer are determined.
Thus, a gap calculating means 42 for calculating the gap δ is configured.

After calculating the gap δ in the above step S2, the step
In S3, it is determined whether or not the gap δ is within the allowable range (G−ε <δ <G + ε). If the determination is YES, the process returns to step S1, and if the determination is NO, an alarm is issued in step S4.
Further, in parallel with the determination in step S3, the power P required for transporting the pallet P is calculated in step S5. The power P is calculated by using a power calculation map as shown in FIG. 7 and using the gap δ obtained in step S2 and the weight W of the transferred object as parameters. As can be seen from the above map, the power P increases as the gap δ increases and as the weight W of the transferred object increases (W3>W2> W1).

After calculating the power P in step S5, the power P is converted to a thrust F in step S6. This conversion is performed by the following equation.

F = P / (K · τ · p) = P / α where K is a coefficient, τ is the pole pitch (cm), p is the number of poles of the primary conductor, and α = (K · τ · p) is the transport time Is the rising acceleration. The units of the power P and the thrust F are N
(Newton) and Kw.

Subsequently, a current command value is calculated in step S7. 8th
The figure shows the electrical circuit that performs this operation. In the figure, 51
Is a speed control unit for controlling the transport speed. The speed control unit 51 receives the difference between the speed command vm 'and the actual transport speed vm detected by the speed sensor 31. Reference numeral 52 denotes an OR circuit that receives a pulse signal output from the speed control unit 51 and a pulse signal output from the speed sensor 31. 53 counts a loose signal output from the OR circuit 52, and measures timing. The signal of the arc angle θ0 is
These are counters that output to the A converters 54a, 54b, 54c, respectively. The three D / A converters 54a, 54b, 54c are for obtaining a current command value ia, ib, ic of three-phase alternating current from the firing angle θ0,
The current command values ia, ib, ic are obtained by the following equations. However, K = (2/3) ^1/2 .

ia = K · i · sin θ0 ib = K · i · sin (θ0−2π / 3) ic = K · i · sin (θ0 + 2π / 3) The current command signal from each of the D / A converters 54a to 54c is a transistor inverter. Output to the circuit 55. In the transistor inverter circuit 55, the excitation control of the linear motor coil 10 is performed based on the current command signal, and the actual current values ia ′, ib ′, ic ′ at that time and the current command values ia, ib, The feedback control is performed based on the difference from the IC. In FIG. 8, reference numeral 56 denotes an F / F interposed between the speed sensor 31 and the speed control unit 51.
The V converter 57 is a V / F converter interposed between the speed control unit 51 and the OR circuit 52.

Next, the operation of the above embodiment will be described. In the case where the pallet P on which the body B is placed is sequentially fed to each work station by the linear motor 23, the work is performed between one adjacent work station, for example, in FIG. Between the first work station ST1 and the second work station ST2,
Under the control of the station controllers 32, 32 corresponding to the work stations ST1, ST2, the linear motor coil 10 is excited, and the reaction member 14 is actuated by the electromagnetic action between the linear motor coil 32 and the reaction member 14.
Pallet P on which body B is placed
Is transported between the work stations at a predetermined speed v that changes with time as shown in FIG.
The control of the transfer of the pallet P between the adjacent work stations is performed by the station controller 32 corresponding to the work station on the upstream side in the transfer direction in the first half of the transfer, and the work on the downstream side in the transfer direction is performed in the second half of the transfer. This is performed by the station controller 32 corresponding to the station.

During this transfer, the station controller 32 controls the acceleration detecting means according to the control flow shown in FIG.
The rising acceleration a at the start of the conveyance is detected by 41, and the conveyance is performed based on the rising acceleration a detected by the gap calculation means 42, the weight W of the object to be conveyed, and the conveyance speed v preset according to the weight. The gap δ between the linear motor coil 10 and the reaction member 14 at the time is calculated / estimated. The power P required for conveyance and the current command value are calculated from the gap δ and the weight W of the transferred object.

Then, when the pallet P is transported between the second work station ST2 and the third work station ST3 between the next adjacent work stations, the linear motor coil 10 is excited based on the current command value, The pallet P is transported between the work stations ST2 and ST3 with a predetermined thrust.

As described above, when the pallet P is transported, the linear motor coil 10 is excited with the excitation amount corresponding to the gap δ at the time of the previous transport. The pallet P can be accurately conveyed with a constant thrust for a predetermined time without being affected by the fluctuation of the pallet, and the conveyance can be stabilized.

Moreover, the measurement of the gap δ does not directly measure the gap δ as in a laser length measuring device, but detects the rising acceleration a at the start of conveyance by the acceleration detecting means 41,
The gap δ is determined based on the detected rising acceleration a and the like.
Is indirectly measured and calculated, and the mechanism for the measurement is composed of a speed sensor, etc., and is simple and inexpensive compared to a laser length measuring instrument. It is.

The present invention is not limited to the above embodiment,
Other various modifications are included. For example, in the above embodiment, the present invention is applied to the case where the linear motor coil 10 is used as the stator and the linear motor 23 is used as the reaction member 14 as the mover. The present invention can be similarly applied to a case where the linear motor 23 is formed by providing the reaction member 14 along the transport line and forming the stator while the movable member is provided on the plate member 13 side.

Further, in the above-described embodiment, the case where the transport device A is applied to the vehicle assembly line has been described. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to the case where another transported object is transported.

(Effect of the Invention) As described above, according to the transfer apparatus using the linear motor of the first and second aspects of the present invention, it is set in advance according to the rising acceleration at the time of easy transfer, the weight of the transferred object, and the weight thereof. A gap between the linear motor coil and the reaction member is calculated from the calculated transfer speed, and based on the calculated gap and the weight of the transferred object, a predetermined value is set when the transferred object is transferred between the next work stations. By controlling the amount of excitation of the linear motor coil to obtain the thrust, the thrust can be made constant regardless of the variation in the gap, and the conveyance can be stabilized. In addition, since the detection means has a simple configuration and is relatively inexpensive, it can be easily implemented in terms of cost, and is excellent in versatility.

[Brief description of the drawings]

1 to 9 show an embodiment of the present invention. FIG. 1 is a side view of a transport device, FIG. 2 is a plan view of the same, and FIG. 3 is a cross section taken along line III-III of FIG. FIG. 4, FIG. 4 is a block diagram of a control unit for controlling the linear motor, FIG. 5 is a flowchart showing a control flow for calculating an excitation amount of the linear motor coil, FIG. 6 is a diagram showing a gap calculation map, FIG. 7 is a diagram showing a power calculation map, FIG. 8 is an electric circuit diagram for calculating a current command value, and FIG. 9 is a characteristic diagram showing a speed change during pallet conveyance. FIG. 10 is a diagram corresponding to FIG. 1 showing a conventional example. A: Transport device P: Pallet (transported object) 10: Linear motor coil 14: Reaction member 23: Linear motor 32: Station controller (control means) 41: Acceleration detecting means 42: Gap calculation means

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B65G 54/02 B60L 13/00-13/10 B62D 65/00

Claims (2)

(57) [Claims] 1. A transfer device for sequentially feeding an object to each work station using a linear motor including a linear motor coil and a reaction member, wherein acceleration detecting means detects a rising acceleration when the object is conveyed. And gap calculation means for calculating a gap between the linear motor coil and the reaction member from the rising acceleration detected by the detection means, the weight of the transferred object, and a transfer speed set according to the weight, Control means for controlling the amount of excitation of the linear motor coil so as to obtain a predetermined thrust when transferring the transferred object between the next work stations based on the gap determined by the calculating means and the weight of the transferred object; And a transfer device using a linear motor. 2. A gap calculating means maps a relationship between a rising acceleration at the time of transporting an object to be transported, a weight of the object to be transported, and a transport speed and a gap according to the weight, and obtains a gap from the map. A transfer device using the linear motor according to claim 1.