JPS6122858A - Drive control of gypsum cutter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field of invention The present invention relates to a drive control method for a cast cutting machine.

Technical Background of the Invention and Problems Therein Generally, in the treatment of a bone fracture, it is necessary to cover and fix the affected area with a plaster cast or the like, and then cut and remove the cast after the fracture has healed.

For this reason, conventionally, a circular saw cutter with a triangular cutting edge on the outer periphery is electrically vibrated reciprocatingly in the circumferential direction at an amplitude of 2 to 3 fields, and when it is pressed against a cast and cut, the lower cotton bandage can be cut. The hardened cast is cut by the touch of the needle. Therefore, the operator is required to cut the cast quickly while being extremely careful to prevent the cutting blade from touching the skin, which places a heavy burden on the operator. Particular attention should be paid to areas where bones protrude close to the skin, such as the bulge. Furthermore, since the treatment is performed based on the senses of the practitioner, it also gives the patient a significant sense of fear.

Purpose of the Invention The present invention has been made in view of the above-mentioned problems.The cutting blade of the vibrating cutter can be applied to the skin, without depending on the feeling of the practitioner.
Automatically reduces or stops the vibration when approaching
1 (Gibbs tW that can be used to ensure safety)
The object of the present invention is to provide a J-section drive control method.

Summary of the Invention The present invention uses the capacitance between the cutting blade and the skin as the oscillation frequency determining element of the oscillator, detects the change in the oscillation frequency when the cutting blade approaches the skin, and reduces the vibration of the cutter. By weakening or stopping the skin, it is possible to (M fft4).

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

First, the structure of a plaster cutting machine 1 used in this embodiment will be explained with reference to FIG. 2 is a step horn type ultrasonic vibrator, which is driven by an electrostrictive element or a magnetostrictive element. Here, regarding the imaging mode of the ultrasonic transducer 2, when it is driven by the drive power supply at the ultrasonic frequency (natural resonant frequency), the axial direction of the ultrasonic transducer 2 is λ/2' (λ is the wavelength of the resonant frequency).
At Il, vibration occurs and longitudinal vibration is produced. A cutter 4 having a cutting edge 3 is provided perpendicularly to the tip of the small diameter section 2a of the a sonic vibrator 2 to
5 and washer 6.

Therefore, when cutting the cast 7, hold the ultrasonic transducer 2 in your hand, apply the cutting blade 3 to the cast 7, and rotate it slightly in the direction of arrow A, as shown in Fig. 2, in the cutting direction indicated by the arrow. Proceed to. At this time, when the ultrasonic vibrator 2 is longitudinally vibrated in the axial direction at an ultrasonic frequency, the cutter 4 provided at the tip is ultrasonically vibrated in the thickness direction orthogonal to the cutting direction. Therefore, the cast 7 on the side surface of the groove cut by the cutting blade 3 is pulverized and cut open by vibration in the thickness direction, so that the cast 7 is easily cut and the vibration noise is reduced. Here, cast 7 to be cut
is wrapped on top of the lower cotton bandage 9 wrapped on the skin 8 and solidified.

The ultrasonic vibrator 2 is driven by the driver 10, but when the load energy exceeds the set 1 Noher (according to the driving voltage or current) This is to generate a load signal &L that increases U.

Furthermore, the self-excited oscillator 12 as the oscillator 1 uses the capacitance between the tip of the cutting blade 3 of the cutter 4 and the skin 8 as its oscillation frequency determining element.
3 is connected to the cutter 4, and the common lead 14 is connected to the skin 8.
It is connected to the. Due to this.

The oscillation frequency of the self-excited oscillator 12 is set to gradually decrease due to a change in the capacitance between the cutting blade 'I when it approaches the skin 8. Further, the cutter 4 and the ultrasonic vibrator 2 are electrically insulated by an insulator such as ceramic. The optical frequency signal So of this oscillator 12
Gz varies depending on the signal HIA15.
The gate circuit 16 or 1 of No.j which is manually input to the gate circuit 16゜ with G2 and selected by the changeover switch 18
7, and is manually inputted to the counter 19 and clicked 1-. The data counted by this counter 19 is stored in a memory 21 through a switch 20.

The data in the memory 21 is input to a comparator 24 through a signal line 22, and the count data from the counter 19 is input through a signal line 23 to a comparator 24 for comparison. When the data is larger than , a control signal Sc is sent to the driver 10 via the signal line 25 to control the vibration of the ultrasonic vibrator 2 and therefore the cutter 4. Here, the changeover switch 18 and switch 20 are controlled by the load signal SL, and are in the state shown when the load signal S+ is at O level (gate circuit 16 selection and switch 2
0 is ON), and it is switched when it is level (gate circuit 17 selected and switch 20 are OFF). Further, the gate time G+IGz is set as (jl<G2).

In such a configuration, operation control is performed in the following sequence, which will be explained with reference to the timing chart of FIG. First, a clock pulse CLK is generated every 7 fixed times, and each operation is performed in synchronization with this clock pulse CLK.

Now, consider a period T1 during which the tJ) blade 3 of the cutter 4 attached to the tip of the +tfJ i's wave transducer 2 does not touch the cast 7. In other words, it is a non-cutting time, the driving power from the driver 10 is small, and the load signal S1.
l: Eye 111 is at 0 level as shown in Figure (b).

Therefore, the 1'Jj conversion switch 18 selects the gate circuit 16, and the switch 20 is in the ON state. Therefore, the oscillation frequency signal SO of the oscillator 12 is inputted to the counter 19 through the gate circuit 16 with the gate time G1, and the count number is accumulated as shown in FIG.
When the gate circuit 16 closes, the count value is held.

At the same time as this gate circuit 16 closes, the data of the counter 19 is transferred to the memory 2 via the ON switch 20.
Sent to 1.

The data is stored as shown in (I) of the same figure. That is, this stored data becomes the reference frequency data.

However, let's talk about the period T2 during which the 1J blade 3 is applied to the cast 7 and the cast 7 is cut. At this time, cut
11 (due to the pile, the power supplied from the driver "10" increases and the load signal SL becomes rubertonal. As a result, the selector switch 18 switches to the gate time (selects the gate circuit 17 side of 32), and at the same time the switch 20 OF
F. Therefore, the oscillation frequency signal So of the oscillator 12 is inputted to the counter 19 through the gate circuit 17, which is the gate tie A G 2, and is inputted to the counter 19 as shown in FIG.
1-number is accumulated, and when the gate circuit 17 closes, the value is held in the counter 1. Since the switch 20 is OFF, the new count number by the counter 19 is input to the comparator 24, and the new count number is inputted to the comparator 24 as shown in the figure.
It is compared with the reference frequency data in the memory 21 based on the comparison command pulse shown in f). However, in this T2 period, gate time G2. Since GL is set as G2>GL, even if the cutting blade 3 slightly approaches the skin s8 side, the new count number by the counter 19 is larger than the reference frequency data in the memory 21, so the control signal S
C does not occur, and the cutting operation of the cast 7 continues.

In this way, the cutting of the cast 7 progresses, and the cutting edge 3 or the skin 8
When the oscillation frequency of the self-excited oscillator 12 decreases and the new count number by the counter 19 becomes smaller than the basic frequency data in the memory 21 as shown by period T3 in FIG. 24 outputs a control signal SC for controlling the driver 10 (for this reason, the cutting blade 3
The gate times Gl and Gz of the gate circuits 16 and 17 are set so that this output condition is satisfied when the cutting edge 3 approaches the lower cotton bandage 9. When it approaches the set interval, G2>0
Even if the gate time G2 is set to be 1, the oscillation frequency of the self-excited oscillator 2 will decrease until the new count number becomes lower than the reference frequency data in the memory 21, and the oscillation frequency will be output from the comparator 24. The driver 10 is controlled by the control signal Sc to weaken or stop the ultrasonic vibration of the cutting blade 3, thereby protecting the skin 8 from the cutting blade 3.

By the way, when the cutting blade 3 is moved slightly away from the skin 8, the I drive becomes stronger again, but since the cutting blade 3 is still loaded with the cast 7, the switch state remains unchanged and the gate time remains at G2. In addition, since the memory 21 also holds the reference frequency data before starting cutting for the first time, the operation of detecting the approach between the cutting blade 3 and the skin R8 is continued as described above.

On the other hand, when the cutting blade 3 is separated from the cast 7, the load on the cutting blade 3 decreases and the load signal SL becomes 0 level, so the gate circuit 16 is selected again and the switch 20 is turned on. Therefore, the data in the memory 21 is updated and reset to the oscillation frequency signal SO of the self-excited oscillator 12 at this time. In other words, a cast.

The cutting resistance during cutting is detected by changes in the vibration driving voltage or current, and by utilizing the fact that the cutting resistance decreases when not cutting, the 1llli reaction of the cutting blade 3 from the cast 7 is detected, and the self-excited oscillator 12 is activated. It updates and resets at the reference frequency. This corrects frequency instability and allows accurate detection of the distance between the cutting blade 3 and the skin 8 to control vibration.

In this way, the oscillation frequency of the oscillator 12 is compared every time the cutting blade 3 separates from the cast 7 after starting to cut the cast 7.
<I+Dana memory 21 data will be updated, so
It is sufficient if it is stable within that period, and a self-excited oscillator in the cylinder can be used.In this embodiment, the cast cutting machine 1 is used to reduce the vibration noise to reduce the cutting effect. In order to increase the height of vibration, the cutter 4 using ultrasonic vibration r2 is vibrated in the thickness direction1↓・C cast 7 is cut. The same can be applied to the type of cutting method. Alternatively, the cutter may be vibrated back and forth in the circumferential direction by an ultrasonic vibrator.

Effects of the Invention In the present invention, as described above, the change in capacitance between the cutting blade of the cutter and the skin is detected as a change in the oscillation frequency to control the vibration of the cutting blade. The cast cutter can be operated with confidence without damaging the skin, significantly alleviating the patient's fear.Furthermore, each time the cutting blade leaves the cast, the base 7 (+4) value of the frequency is updated. By resetting, even if a simple self-excited oscillator is used, more reliable vibration control can be performed.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an external perspective view, FIG. 2 is a block diagram, and FIG. 3 is a timing chart.

Claims (1)

[Claims] 1. The capacitance between the cutting edge of a vibrating cutter and the skin is used as the oscillation frequency determining element of an oscillator, and the change in the oscillation frequency of this oscillator is detected to control the vibration of the cutter. A drive control method for a plaster cutting machine, characterized in that: 2. The capacitance between the cutting blade of the vibrating cutter and the skin is used as the oscillation frequency determining element of the oscillator, and the change in the oscillation frequency of this oscillator is detected to control the vibration of the cutter, and the vibration to the cutter is controlled. A drive control method for a cast cutting machine, comprising: detecting that the cutting blade has separated from the cast due to a change in drive voltage or current, and updating and resetting reference frequency data for detecting a change in oscillation frequency.