JPS6288525A - Monitoring apparatus for machine-screw fastening machine - Google Patents

Abstract

PURPOSE:To improve the state detection precision of a machine-screw fastening machine by installing a detecting tool which has a sensor, amplifying part, memory part for previously memorizing a standard vibration, and a comparison part for comparing the generated vibration with the memorized standard vibration, onto a machine-screw fastening machine. CONSTITUTION:In a machine screw fastening machine 2, a transfer board 23 is installed onto a supporting frame 22, and a twist-drill tool 5 is fixed onto an elevation board 24. A twist drill 3 and a sensor S are installed. Then, a detecting tool D, controlling tool 9, electric motors MD and ME, etc. are connected from the sensor S. The detecting tool D has the amplifying part for the sensor S, memory part for previously memorizing a standard vibration, and a comparison part for comparing the generated vibration and the standard vibration. The operation of the detecting tool D permits the output of the signals according to the normal and abnormal states of the twist drill 3. The control tool 9 operates the electric motors MD and ME, alarm, etc. Therefore, the detection precision is improved in comparison with that in monitoring by an operator in the conventional.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a monitoring device for a screw tightening machine that can accurately detect the state of the screw tightening machine by comparing the vibration generated by the screw tightening machine with a reference vibration.

[Background technology]

For example, in a production line for architectural panels used for walls, floors, etc. using the dry method, a screw tightening machine is used to screw the facing material to the frame. In addition, such a screw tightening machine is equipped with a screw tightening machine main body equipped with a screw supply pipe that automatically supplies screws, and a drill tool for drilling a pilot hole prior to screw tightening. When an overload is applied due to a defective drill such as, the drill breaks. If such breakage is left unnoticed, or if the drill reaches the end of its life, the pilot hole may not be drilled correctly.
The screw cannot fall down the screw supply pipe to a predetermined position correctly, which causes clogging of the screw supply pipe, as well as failure of the screw tightening machine body, reduction in screw tightening accuracy, and reduction in product quality.

Therefore, it is important to accurately grasp the operating state of such a screw tightening machine, especially the state of the drill tool, ie, the normal state, overload state, drill breakage state, drill lifespan state, etc.

However, conventionally, such conditions have been monitored by workers, which tends to be overlooked, resulting in the above-mentioned problems.

The present invention was completed by focusing on the fact that the sound emitted by a screw tightening machine changes depending on its condition, and by analyzing the spectrum of the vibration generated by the screw tightening machine, we found a correlation between the condition and the generated vibration. It is.

[Purpose of the invention]

An object of the present invention is to provide a monitoring device for a screw tightening machine that can accurately detect the state of the screw tightening machine by comparing generated vibrations generated depending on the state of the screw tightening machine with a reference vibration.

[Disclosure of the invention]

An embodiment of the present invention will be described below based on the drawings.

In Figs. 1 and 2, a monitoring device 1 for a screw tightening machine includes a sensor S attached to a screw tightening machine [2], an amplified part A, a memory part K that stores reference vibrations in advance, and a memory part K that stores generated vibrations and vibrations in the memory part. Screw tightening machine 2 having a comparison part C for comparing with reference vibration
The sensor is equipped with a detection device for detecting the state of the sensor.

As shown in FIG. 2, the screw tightening machine 2 includes a movable platform 2 that can slide in a direction transverse to the conveyance direction using a dovetail groove, for example, on a support frame 22 that straddles a workbench 21 made of a roller conveyor.
3 is attached so that its position can be adjusted, and the drill tool 5 is fixed to a lifting table 24 that is attached to the moving table 23 so as to be able to move up and down. Further, the drill tool 5 has the drill 3 attached to a chuck provided on the downward output shaft of the electric motor MD. Also, the lifting platform 2
4 can be lowered and raised by forward and reverse rotation of the electric motor MP by screwing together a screw shaft 25 connected to an electric motor ME with a speed reducer disposed above the moving table 23. Further, the screw tightening ff12 includes a screw tightening machine main body (not shown) that automatically supplies screws to the prepared hole 6 drilled by the drill tool 5 and tightens the screws on the downstream side of the drill tool 5. There is. In this example, the screw tightening machine 2 is used to screw a flat plate-shaped face material W2 made of wood to a framework W1 made of rectangularly joined channel steel, and the framework W1 and the face material W2 are A construction panel is formed by fixing with screws. Further, the screw tightening machine 2 is arranged on the production line of the construction panel.

The sensor S is attached to the drill tool 5 of the screw tightening machine 2, and detects vibrations generated depending on the state of the drill tool 5 of the screw tightening machine 2. Further, the sensor S is composed of a microphone in this example. Here, the generated vibration will be explained based on FIG.

FIG. 4 shows a spectrum analysis of the output of the sensor S, with the horizontal axis representing the frequency f, the vertical axis representing the intensity P, and both axes representing the decibel scale. As a result, the pilot hole 6 was successfully drilled. As shown by the curve G1, when the frequency is lower than rt, the distribution is biased toward low frequencies, and the intensity is constant and low at frequencies above the shoulder frequency rt. Also, when the drill 3 breaks, the shoulder frequency f3 as shown by curve G3
As the value increased, so did its intensity. In addition, in an overload state, the load is distributed in the area surrounded by the curve G1 and the curve G3, and as the overload increases, the shoulder moves from the shoulder of the curve G1 to the shoulder of the curve G3. The situation changed rapidly and the drill broke. Furthermore, when the cutting edge of the drill 3 is worn out and has reached the end of its service life, as shown by the curve G4, the above-mentioned significant shoulder does not appear, and the intensity distribution remains almost constant up to a high frequency exceeding the frequency f3. Therefore, there was a high-intensity portion exceeding the curve G3 at a position exceeding the frequency f3.

Therefore, the detection output of the sensor S is, for example, frequency fl, f
A normal state, an overload state, and a broken state can be detected by filtering in the frequency band B1 between 3 and the frequency band B2 located above the frequency f3 as described above, and comparing the levels.

The detection device includes an amplification part A that amplifies the detection output of the sensor S, and an output to the amplification part that is set in the predetermined frequency band B1.
, B2, and a memory section that stores in advance reference vibrations generated according to each state of the screw tightening machine 2, which are represented by the curves G1, G3, and G4, and the width increasing section. A and filter parts F1 and F
The comparison section C compares the generated vibration filtered in step 2 with the reference vibration. Moreover, the filter parts F1 and F2 are the width-enhancing part A.
The sensor is connected in parallel to the output terminal of the sensor, and has a detection circuit whose output is a DC output proportional to the input. Also comparison part C
consists of a comparator, as illustrated in Figure 3,
When the voltage at the plus input terminal is greater than the voltage at the minus input terminal, the output becomes "1", and the comparator C has a comparator CL that connects the plus input terminal to the filter section F1.
C2, and a comparison section C3 which is also connected to the filter section F2. In addition, in this example, as shown in FIG. 3, the storage section includes a variable resistor VR connected between the positive and negative power supplies +E and -E, and its slider is connected to the negative input terminal of the comparison section C. 1, K2, and K3 are provided in storage units connected to each comparison unit CL C2 and C3, respectively.

By adjusting the slider, the storage section Kl can be connected to the comparison section C.
1, the frequency band 81 of the curve G3 is connected to the negative input terminal of
A reference voltage L1 corresponding to the portion is applied. Therefore, the storage unit 1 stores the reference vibration of the state immediately before the drill 3 breaks.

Further, in the storage section 2, a reference voltage L2 corresponding to the frequency band 81 portion of the curve G1 is similarly applied to the minus input terminal of the comparison section C2, and the reference vibration in the normal state immediately before the overload is stored.

Further, in the storage section 3, a reference voltage L3 corresponding to the frequency band 82 portion of the curve G4 is applied to the minus input terminal of the comparison section c3, and the reference vibration of the life state of the drill 3 is stored.

Next, the operation of the detection device configured as described above will be explained.

When the drill 3 has reached the end of its service life, the output voltage VF2 of the filter section F2 is equal to the reference voltage L, as shown in FIG.
3, the output V3 of the comparator c3 becomes "1". At that time, the outputs VI V2 of the comparators C1 and C2 are "0".
, becomes "1".

In addition, when the drill 3 is broken, the output voltage VFI of the filter section F1 exceeds the reference voltage L1 as shown in FIG. They become "1" and "0".

Further, in an overload state, as shown in FIG. 7, the output voltage VFI exceeds the reference voltage L2, the output ■2 becomes "1", and the outputs ■1 and v3 both become "0".

Also, when the drill tool 5 is properly drilling the pilot hole 6,
The output voltage VFI is below the reference voltage L2, and each output V1
, v2, and v3 are all rOJ.

The outputs 1, v2, and v3 in each state are summarized in a table and shown in FIG.

In this way, the detection tool can output output signals that correspond one-to-one according to each state of the screw tightening machine 2, and can detect the state of the screw tightening machine 2.

Further, in this example, the detection device is connected to the control device 9, and the detection device is connected to the control device 9.
is the electric motor MD, M by the outputs ■1, v2, ■3.
E, controls the irises, etc.

Next, the operation of the screw tightening machine 2 will be explained based on FIG. 9.

The electric I31MD is rotated and the workpiece W consisting of the framework W1 and the face material W2 is carried in. After positioning the workpiece W using a positioning tool (not shown), the electric motor ME is rotated in the normal direction, and the drill tool 5 is lowered. At the same time, the screw tightening machine monitoring device 1 is activated to detect the state of the screw tightening machine 2. When the life of the drill 3 is reached, the control device 9 flashes the alarm and the drill replacement lamp to prompt the worker to replace the drill 3.
The worker stops the line and replaces the drill 3.

Also, when the drill 3 breaks, the control device 9 activates a loud alarm and stops the line.

In an overloaded state, the electric motor ME is once rotated in reverse to raise the drill tool 5, performing a so-called step-back, and then the electric motor ME is rotated in the normal direction again.

In addition, in a normal state, the lowering limit of the drill tool 5 is detected by, for example, a limit switch, and the electric motor ME is reversed to raise the drill tool 5. After similarly detecting the upper limit of the drill tool 5, the electric motor ME is stopped and the workpiece W is transported to the main body of the screw tightening machine. Also, the screw tightening machine body has pilot hole 6.
Insert the screw into and tighten the screw.

In addition, in the screw tightening machine monitoring device 1 of the present invention, the sensor S may be a microphone or a piezoelectric acceleration sensor, for example, as long as it can convert vibrations into electrical changes. In addition to an analog circuit comprising a comparison section C consisting of a filter section and a comparator, the detection device also includes a comparison section consisting of a microprocessor, which performs, for example, fast Fourier transform on the generated vibrations, and stores them in advance in a storage section consisting of RAM, ROM, etc. It is also possible to employ a digital circuit that calculates and compares the stored reference vibration and its vicinity. In addition, the detection device includes a display device that visually indicates each status, for example, by lighting, or a chime.
The screw tightening machine monitoring device of the present invention can be modified in various ways, such as by adding a sounding device such as a buzzer or a bell.

〔Effect of the invention〕

Like a savior, the screw tightening machine monitoring device of the present invention includes a sensor that detects the vibration generated by the screw tightening machine, and a detector that detects the state of the screw tightening machine by comparing the generated vibration with a reference vibration. Compared to conventional methods that rely on worker monitoring, this method significantly improves the accuracy of detecting conditions and prevents oversights, for example, preventing problems such as screw clogging in the screw tightening machine body due to oversight. It can prevent breakdowns, poor screw tightening, etc., and can have many effects, such as improving quality and improving the operating rate of production lines.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a sectional view schematically showing the screw tightening machine, and Fig. 3 is a diagram showing the comparison section and storage section thereof. , Fig. 4 is a spectrum diagram showing the vibration generated in each state of the screw tightening machine, Figs. 5 to 7 are explanatory diagrams explaining the action of the detection tool, and Fig. 8 is a status table showing the output of the detection tool.
FIG. 9 is a flowchart showing the operation of the screw tightening machine. 2... Screw tightening machine, A... Width increase part, B1, B2...
・Frequency band, c, ci~C3-comparison section, D・-detector, Fl, F2
-・Filter section, K, Kl~, 3-・Storage section, S-・Sensor.

Claims (2)

[Claims] (1) A sensor that is attached to a screw tightening machine to detect the vibration generated by the screw tightening machine, an amplifying part that amplifies the detection output of the sensor, and a reference vibration that occurs depending on the state of the screw tightening machine is stored in advance. A screw tightening machine comprising: a memory section for detecting the state of the screw tightening machine; Monitoring equipment. (2) A patent characterized in that the detection tool includes a filter section that passes generated vibrations in a predetermined frequency band, and the comparison section compares the generated vibrations filtered by the filter section with a reference vibration. A monitoring device for a screw tightening machine according to claim 1.