JPH11156649A - Screwing tester and screwing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screwing tester which can perform screwing test of a self drilling tapping screw with accuracy. SOLUTION: A screwing tester and screwing method in this case has followings. A driver bit 8 has a leading end engageable with a screw head. An AC servo motor 5 rotationally drives the driver bit 8. An air cylinder 9 provides the driver bit 8 with thrust. An encoder can sense screwing depth of the screw which is inserted by the driver bit 8. A control means 14 changes over driving of the air cylinder 9 and the motor 5 upon reception of sensing by the encoder 13 the screwing of the screw up to specified depth. A torque sensing means 6 senses a load torque which is received by the driver bit 8 at the time of screw fastening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screwing tester and a screwing method for screwing a screw into a work and testing the screwing characteristics of the screw.

[0002]

2. Description of the Related Art Conventionally, various types of automatic screw tightening machines have been used to fasten screws to a work. For the screws to be tightened, a screw-in test is performed in advance, and necessary data is collected. A screw tester used in the screw test generally includes a driver bit that rotates by being driven by a rotary drive source,
A torque detecting means for detecting a load torque acting on the driver bit is provided. The screw is screwed into a female screw-formed work, and a change in screwing torque during the screwing can be measured.

[0003]

However, the above-mentioned conventional screw test machine drives a rotary drive source until a set time by a timer or a screw torque reaches a predetermined value, and measures a change in torque during the drive. Just because
There are problems such as self-drilling tapping screws, which are not simply screwed into the work, but cannot cope with the test of screws that perform preparation and tapping of the work in the process of being screwed in. It has occurred. That is, since such a screw has different screwing conditions in each processing step such as pilot hole processing and tapping processing, accurate data in each processing step cannot be collected by the conventional screw test machine.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in order to attain this object, the present invention provides:

[0005] The present invention also relates to a screw tightening method for forming a pilot hole in a work and then forming a female screw in the pilot hole when the work is fastened to the work. A pilot hole is formed in the work by applying a thrust to the screw engaged with the bit and driving the rotary drive source at high speed to rotate the screw at high speed, and when the screw reaches the predetermined position, the screw is The method is characterized in that a female screw is formed on a work by weakening the thrust acting on the workpiece and switching the rotation drive source to a low speed to rotate the screw at a low speed.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes a screw tester, which has a base member 2a attached to a frame 2 and a work table 2b. A guide 3 is fixed to the base member 2a, and a driver base 4 is slidably guided by the guide 3. The driver base includes a sliding shaft 4a slidable along the guide 3, and an upper plate 4 disposed at an end of the sliding shaft 4a.
b, a lower plate 4c, and a tool unit T is installed on the lower plate 4c.

The tool unit T includes an AC servo motor 5 (hereinafter simply referred to as a motor 5), which is an example of a rotary drive source, and a torque detecting means 6 connected to the motor 5.
And a driver bit 8 connected to the torque detecting means 6 via a connection mechanism 7. The driver bit 8 is configured to rotate upon receiving the drive of the motor 5. The torque detecting means 6 has a reaction force type torque sensor (not shown) therein, and is configured to detect a rotational load torque acting on the driver bit 8.

The base member 2a is provided with an air cylinder 9 as an example of a thrust applying means. The rod 9a of the air cylinder 9 is attached to the upper plate 4 of the driver base 4.
b. A rotary shaft 10 is rotatably disposed on the base member 2 behind the driver table 4. The rotary shaft 10 has a pinion gear that meshes with a rack 11 fixed to the rear surface of the driver table 4. 12 are mounted so as to rotate together. Also, the rotating shaft 1
A rotary encoder 13 (hereinafter, simply referred to as an encoder 13), which is an example of a depth detecting unit, is connected to one end of the rotation shaft 0. The rotation shaft 10 rotates by a predetermined angle as the driver base 4 moves. And a detection signal such as a pulse signal.

On the other hand, a control means 14 for controlling the driving of the air cylinder 9 and the motor 5 is arranged above the frame 2. The control means 14 is configured to count the detection signal of the encoder 13 and control the motor 5 and the air cylinder 9 when the detection signal reaches a preset value. The control unit counts various data that can be obtained during the screwing test, such as the torque data detected by the torque detecting unit 6 or the data of the screwing depth detected by the encoder 13, for a certain period of time by a timer. A storage device (not shown) such as a memory that stores the data every time
It is configured such that torque characteristics with respect to the screwing depth and the like can be obtained based on the stored data.

On the other hand, the screws fastened to the workpiece by the screw test machine 1 are shown in FIGS.
As will be described with reference to FIG.
A self-drilling tapping screw configured to form a female thread in the prepared hole after machining the prepared hole when it is fastened to the hole, and a drill portion 21 is formed at the tip for forming a prepared hole. I have. The screw 20 is used for fastening a work made of a soft material and a hard material, for example, a work obtained by polymerizing a wood and an iron plate. In order to be able to form a hole, the drill portion is provided with two reamers 22, 22 at the upper part. In the following description, a work 30 obtained by superimposing a wood 31 and an iron plate 32 will be described as an example.

In the screw-in tester 1, the work 30 is arranged on the work table 2b and the work 3
The screw 20 is arranged at the tightening position of 0, and the tip of the driver bit 6 is engaged with the head of the screw 20. And
When a start switch (not shown) is pressed, the driver base 4 is firstly pulled down by the operation of the air cylinder 9, whereby a corresponding thrust is applied to the screw 20. 6 is rotated at a high speed, and the screw 20 is screwed into the work 30. As a result, a hole having a diameter through which the thread of the screw 20 can pass is efficiently formed in the wood 31 by the reamers 22 and 22 of the screw 20, and the iron plate 32 has a diameter below the diameter which can be tapped by the drill portion 21 of the screw 20. Holes are formed efficiently. The reamers 22, 22 of the screw 20 are set to have strength so as to be separated from the screw 20 by contact with the surface of the iron plate 32, and the iron plate 32 is formed with only a pilot hole for tapping.

As described above, when the screw reaches the position where the drill portion 21 penetrates the iron plate 32 as shown in FIG. 4, the number of detection signals of the encoder 13 reaches the first set value. The operation of the air cylinder 9 stops, the thrust acting on the screw 20 is reduced, and the driving of the motor 5 is switched from high speed to low speed. As a result, an extra force acts on the screw thread of the screw 20 or the female screw to be formed by tapping, thereby performing smooth tapping while preventing breakage and deformation thereof. Data can be accurately collected.

Thereafter, when the number of detection signals of the encoder 13 reaches the second set value or when a predetermined tightening torque is generated by the seating of the screw 20, the driving of the motor 5 is stopped, and Complete the screwing operation. During the screwing operation of the screw, the load torque accompanying the screwing of the screw is continuously measured and acquired by the torque detecting means 6 and the control means 14, and this is supplied to the encoder 13.
By comparing the amount of movement of the driver bit 8 measured by the above, that is, the screwing depth, a torque characteristic corresponding to the screwing depth of the screw can be obtained. Also,
Since the AC servomotor 5 used as the rotation drive source has an encoder for detecting the rotation angle, if the encoder is used, the torque characteristic according to the rotation angle of the driver bit 8, that is, the screwing angle of the screw, is obtained. It is also possible to get. Therefore, from these torque characteristics, it is possible to determine a torque value at the time of preparing a hole, tapping, sitting, or the like, or a clear drive switching position of the motor 5 and the air cylinder 9. By setting the screw tightening machine, it is possible to accurately tighten screws such as self-drilling tapping screws.

In the embodiment of the present invention, an encoder is used as the depth detecting means. Alternatively, a sensor unit such as a proximity sensor may be used to detect the amount of movement of the driver bit. Or you may comprise combining these and an encoder.

[0015]

As described above, according to the present invention, the thrust applied to the screw can be changed or the drive of the motor can be switched according to the screwing depth. Thus, it is possible to cope with screwing tests of various kinds of screws such as self-drilling tapping screws that require changing screwing conditions, and in each case, extremely accurate test data can be collected.
Therefore, there is an advantage that the data and know-how obtained in this test can be fed back to contribute to the development of an automatic screw tightening machine or the improvement of screws such as self-drilling tapping screws.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a screw tester according to the present invention.

FIG. 2 is an enlarged partial cutaway sectional view of a main part of the screwing tester according to the present invention.

FIG. 3 (a) is an enlarged front view of a screw tightened by the screw tester according to the present invention, and FIG. 3 (b) is an enlarged plan view thereof.

FIG. 4 is a cross-sectional view showing a state in which a screw is screwed in until a screw is formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw-in tester 4 Driver stand 5 AC servomotor 6 Torque detecting means 8 Driver bit 9 Air cylinder 13 Rotary encoder 14 Control means 20 Self-drilling tapping screw

Claims (4)

[Claims] A driver bit having a tip end engageable with a head of a screw; a rotary drive source for rotating the driver bit; a thrust applying means for applying a thrust to the driver bit; Depth detecting means for detecting the screwing depth of the screw as the screw is screwed in, torque detecting means for detecting a load torque received when the driver bit is screwed in the screw, and wherein the depth detecting means is a driver bit And a control means for switching the operation of the thrust applying means in response to detecting that the screw has been screwed to a predetermined position. 2. The screw tester according to claim 1, wherein the control means is configured to switch the drive of the rotary drive source. 3. The control device according to claim 1, wherein the control device is configured to store the screwing depth data detected by the depth detecting device and the torque data detected by the torque detecting device. The screw-in tester according to 1. 4. A method of screwing a screw into a female screw after forming a pilot hole in a work, wherein a thrust is applied to a screw engaged with the driver bit by a thrust applying means and the screw is rotated. By driving the drive source at high speed and rotating the screw at high speed, a pilot hole is formed in the work, and when the screw reaches a predetermined position, the thrust acting on the screw is reduced and the rotary drive source is switched to low speed A method for screwing a screw, wherein a female screw is formed on a workpiece by rotating the screw at a low speed.