JPH0248179A - Nut runner controller - Google Patents

Abstract

PURPOSE:To greatly improve the tightening accuracy by providing a correction part which corrects the detection signal sent from a hole element detector and generates the stable correction output to control the turning of a brushless motor. CONSTITUTION:The output characteristics of a hole element detector 9 is stored in a memory for every brushless motor. Then based on the output characteristics of the hole element detector 9 for every brushless motor, the interval between turning pulses sent from the hole element detector 9 during operation of the a nut runner 1 is corrected by a correction part 20. And according to this correction output, the brushless motor 2 is controlled to turn, whereby properly executing the automatic bolt tightening operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a nut runner control device, and more particularly to a device for controlling automatic tightening of bolts by a simple nut runner having a Hall element detector.

[Conventional technology]

Nut runners used for automatically tightening bolts are generally equipped with a torque transducer that detects the tightening torque that occurs during operation of the nut runner. In this type of nut runner, when bolts are tightened, the nut runner is driven and controlled according to the bolt tightening mode based on a torque detection signal output from the torque transducer. However, the torque transducer is expensive, and therefore, when a nut runner having this torque transducer is used, there is a risk that the cost of a product in which bolts are tightened may be increased.

Therefore, in recent years, a simple nut runner that uses a relatively inexpensive Hall element detector instead of an expensive torque transducer has been gaining popularity. An example of the basic structure of this simple nut runner will be explained with reference to FIGS. 5 and 6. In the nut runner (1) shown in FIG.
) is a driving motor that generates force for tightening, and is a synchronous AC servo motor using a brushless motor with a Hall element detector. (3) is a reducer that decelerates the motor rotation and generates a large torque.
) is connected to the output shaft (2a) of the (4) is the reducer (3
) The bolt is fixed to the main shaft (3a) with an axotiment, which is inserted into the through-holes (5a) and (6a) of the two members (5) and (6) to be bolted, and is mated to the nand (7). the head of the bolt (8).

(9) is a Hall element detector provided in the brushless motor (2), and as shown in FIG.
) and Hall elements (lla) (11b) (11(11c)) fixedly arranged near the outer periphery of this rotary plate (10).
It consists of. The outer peripheral portion of the rotary plate (10) is magnetized with S and N poles in a predetermined arrangement relationship. (12
) is a control unit that controls the rotation of the brushless motor (2) of the nut runner (1) based on the detection output of the Hall element detector (9).

When tightening the bolt (8) with the nut runner (1), the detection signals Sa, Sb, Sc output from the Hall element detector (9) and the detection signal Sas sb
, Sc, the rotation of the brushless motor (2) is controlled by the motor control current 1o sent from the control unit (12). At this time, the seating point of the bolt (8) is detected by the detection signals Sa, Sb, and Sc from the Hall element detector (9), and the bolt (8) is tightened at high speed rotation until the bolt (8) is seated. To save time, the bolt (8) is tightened at low speed after the seating point to reduce variations in tightening torque.

[Problem to be solved by the invention]

By the way, in the nut runner (1) having the brushless motor (2) with a Hall element detector described above, the output characteristics of the Hall element detector (9) are linearly stabilized due to variations in the positioning accuracy of the Hall element detector (9). hard. That is, in the Hall element detector (9), the rotating plate (1o)
Hall elements (11a) (11b) (1
The mounting position of the rotating plate (1C) may vary, or the rotating plate (10
), the detection signals Sa, Sb, and Sc output from the Hall element detector (9) vary. If the output characteristics of the Hall element detector (9) are unstable in this way, the output characteristics of the Hall element detector (9) will be unstable even though the brushless motor (2) is rotating at a constant rate. Brushless motor based on (2)
Due to rotation control, bolt tightening sometimes causes speed fluctuations and torque fluctuations, making it impossible to accurately detect when the bolt (8) is seated, and the accuracy of tightening using the nut runner (1) is significantly reduced. was there. In addition, in order to reduce problems caused by variations in positioning accuracy of the Hall element detector (9) mentioned above, a second-order lag filter (not shown) is provided between the Hall element detector (9) and the control section (12). The detection signals Sa, Sb, and Sc of the element detector (9) are averaged to stabilize their output characteristics. However, the detection signal Sa from the Hall element detector (9),
Since Sb and 'Sc are delayed by a second-order lag filter, the responsiveness to motor control deteriorates, so this is not a preferable method.

Therefore, an object of the present invention is to stabilize the output characteristics of a Hall element detector without using a second-order lag filter.

[Means to solve the problem]

The present invention has been proposed in view of the above-mentioned problems, and is a device for driving and controlling a nut runner having a brushless motor with a Hall element detector, the output characteristics of the Hall element detector during constant speed rotation of the brushless motor. By having a correction section that stores and holds the information in the memory, performs arithmetic processing on the rotational pulse interval output from the Hall element detector during operation of the nut runner, and the output characteristics of the Hall element detector, and sends out a correction output. The above objective has been achieved.

[Effect]

According to the present invention, the output characteristics of the Hall element detector are stored and held in the memory for each brushless motor, and the Hall element is detected during operation of the NAND runner based on the output characteristics of the Hall element detector for each brushless motor. The correction unit corrects the rotation pulse interval output from the device, and the corrected output controls the rotation of the brushless motor to perform proper automatic bolt tightening.

〔Example〕

An embodiment of the nut runner control device according to the present invention will be described with reference to FIGS. 1 to 4. However, the same or corresponding parts as in FIGS. 5 and 6 are given the same reference numerals, and the explanation thereof will be omitted.

The feature of the present invention is as shown in FIG.
) is provided with a correction section (20) that corrects the outputs Sa, Sb, and Sc from the Hall element detector (9) attached to the brushless motor (2). This correction section (20)
The brushless motor (2) is controlled by the motor control current 11 sent from the control unit (12) based on the corrected output S
) to control the rotation.

FIG. 2 is a block diagram of a specific circuit configuration of the correction section (20), in which (21) is a Hall element detector (9).
) of each Hall element (11a)(11(11b)(1
1c) is an arithmetic processing circuit connected to E, which stores and holds the output characteristics of the Hall element detector (9).
It has a memory (22) such as EPRO1'1. (23
) represents each Hall element (11) of the Hall element detector (9).
a) <11 b) A combinational circuit of exclusive OR circuits connected to (11c) (hereinafter simply referred to as Ex-OR
(referred to as a circuit), whose output signal is a rotation pulse signal S
2, as described later (see Figure 4), is S 2 =Sa
XSc 10Sa XSb X5cS 2 -3a X
Sb 'X Sc + Sa X Sb X Sc +
Sa X Sb X Sc+5aXSbXSc15a
XSbXSc: Consists of a logical expression ERROR. (
24) is a one-shot multivibrator circuit (hereinafter simply referred to as one-shot circuit) connected to the output of the Ex-OR circuit (23), which detects the timing of the rise and fall of the pulse signal. (25) is a quanta circuit connected to the output of the one-shot circuit (24), which generates a pulse signal from the one-shot circuit (24) at the timing of the clock pulse signal CO output from the clock pulse generation circuit (26). The rising and falling edges of are counted and outputted to the arithmetic processing circuit (21). (
27) represents each Hall element (ll) of the Hall element detector (9).
a) A rotational direction discrimination circuit connected to (11b) (11c) discriminates the rotational direction of the brushless motor (2) and outputs it to the arithmetic processing circuit (21). (28) is a D/A conversion circuit connected to the output of the arithmetic processing circuit (21), and the control unit (12) is connected to the output of this D/A conversion circuit (28).
) are connected.

When tightening the bolt (8) with the nut runner (1), first the brushless motor (2) is tightened as shown in Figure 3.
) is rotated at high speed until the bolt (8) is seated at time t2.

and starting point t.

At time t1, when the brushless motor (2) starts to rotate at a constant speed in the initial period in the no-load region Dl from the time of seating to the time of seating t2, the output characteristics of the Hall element detector (9) are adjusted by the correction unit (20). Memory (22) in the calculation processing circuit (21)
to be stored in memory. For example, as shown in FIGS. 4(a) to (C), each Hall element (11a) (11b) (
11c) outputs detection signals Sa, Sb, Sc having 6 pulses per rotation of the rotary plate (10), then each of the Hall elements (11a) (11b) (1
Based on the detection signals Sa, Sb, and Sc from 1c), a rotation pulse signal S2 as shown in FIG. 4(d) is output from the Ex-OR circuit (23). The one-shot circuit (24) detects the rise and fall of each pulse train of this rotation pulse signal S2 and converts it into the rotation pulse signal s3 shown in FIG. 4(e). Then, in the counter circuit (25), the rotation pulse interval [dt,
d2... is counted based on the clock signal Co from the clock pulse generation circuit (26), and the arithmetic processing circuit (21
). The arithmetic processing circuit (21) converts the rotation pulse intervals d1, d2, . . . into reciprocal numbers and stores them in the memory (22).

The point in time when the output characteristic of the Hall element detector (9) is stored and held in the memory (22) of the arithmetic processing circuit (21), that is, the point in time when the brushless motor (2) starts to rotate at a constant speed (11). 3) until reaching the seating time t2 of the bolt (8), each Hall element (lla) (l
Detection signals Sa, Sb output from lb) (IIC)
, Ex/OR circuit (23) using Sc as described above.
, one-shot circuit (24) and counter circuit (25)
), and the above detection signals Sa, Sb, S
The rotation pulse intervals d1, d2, . . . corresponding to c are sent to the arithmetic processing circuit (21). This arithmetic processing circuit (21)
Now, the above rotation pulse intervals d1, d2,... and memory
(22) The Hall element detector (9
) are the output characteristics of rotation pulse intervals d1, d2,...
Rotating pulse interval d1 sequentially output from the Hall element detector (9) by multiplying by the reciprocal value crown of , treasure c, etc.
, d2, . . . are corrected. The correction output S1 from the arithmetic processing circuit (21) of the correction section (20) is converted into analog by the D/A conversion circuit (28) and sent to the control section (12). In this way, the controller (12) corrects variations in the rotational pulse intervals d1, d2, . Brushless motor (2)
) can be rotated at high speed based on the correction output S1 obtained by stabilizing the detection signals Sa, Sb, and Sc from the Hall element detector (9) in the correction section (20).

The stable correction section (20
) Brushless motor (2) based on the corrected output S1 from
When the bolt (8) is seated after high-speed rotation, the ball element detector (9) outputs detection signals Sa, Sb,
The seating time t2 can be accurately detected by changes in the rotation pulse intervals d1, d2, . . . of the Sc. Based on this, an output signal from the arithmetic processing circuit (21) causes the brushless motor (2
), rotate it at low speed and tighten the bolt (8).

〔Effect of the invention〕

According to the present invention, the detection signal output from the Hall element detector is corrected by the correction section, and the rotation of the brushless motor is controlled using this stable correction output, so there is no variation in the positioning accuracy of the Hall element detector. Rotation control without speed and torque fluctuations can be realized even when the nut runner is fastened, greatly improving the accuracy of tightening, and since there is no need for a second-order lag filter or the like as in the past, a nut runner with good responsiveness can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the nut runner control device according to the present invention, FIG. 2 is a circuit configuration block diagram showing a correction section of the device shown in FIG. Tightening is a characteristic diagram showing the relationship between time and rotational speed, 4th
Figures (a) to (e) are waveform diagrams showing output signals at each section in Figure 2. FIG. 5 is a schematic configuration diagram showing a conventional example of a nut runner control device, and FIG. 6 is a plan view showing a Hall element detector of the device shown in FIG. (1) - Natsu runner, (9) - Hall element detector, (20) - 11 correction section, (22) Sa, Sb
, Sc-output characteristic, Sl-corrected output. Memory, patent Applicant: Sanyo Kiko Co., Ltd. Representative: Jiangwon Province Let's go!

Claims (1)

[Claims] (1) A device for driving and controlling a nutrunner having a brushless motor with a Hall element detector, which stores and holds in memory the output characteristics of the Hall element detector when the brushless motor is rotating at a constant speed, and when the nutrunner is operating. A nutrunner control device comprising: a correction section that performs arithmetic processing on a rotational pulse interval output from a Hall element detector and an output characteristic of the Hall element detector, and sends out a correction output.