JPH0446688B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drilling machine control device, and in particular, it has an electromagnetic base (electromagnet device) at the bottom as a means for fixing it to a workpiece, and has, for example, The present invention particularly relates to a portable drilling machine control device that includes an electric drill having an annular cutter and a motor for controlling the feed of the electric drill (hereinafter referred to as a feed motor).

(Prior Art) As is well known, when drilling using an electric drill equipped with an annular cutter, a larger torque can be obtained than when using a twist drill.
Although it has excellent cutting performance, on the other hand, there is a possibility that an abnormally large load is applied to the annular cutting tool, which may damage the annular cutting tool or burn out the electric drill.

Therefore, when working with an annular cutter attached to an electric drill, the operator must always be careful not to apply a large load to the annular cutter.

However, it takes extremely skilled people to recognize the magnitude of the load, in other words, to discern whether an appropriate load is being applied to the blade of the annular cutter, or whether an excessive or insufficient load is being applied. Possible only for work.

Therefore, if the drilling machine is operated by a beginner who is not familiar with its handling, it may cause damage to the annular cutter or burnout of the electric drill as described above.
In extreme cases, there is a high risk that the annular cutting tool of the electric drill may swing around as the center of rotation.

Furthermore, it is desirable to turn off the power of the drilling machine immediately after the drilling operation is completed, in order to save power consumption and to prevent breakage of the annular cutter. However, with conventional drilling machines, the operator has to turn off the power switch of the drilling machine after realizing that the drilling work has been completed, which is very tedious for the worker. Also, its workability is not very good.

In order to solve the above-mentioned drawbacks, the present inventors have conducted various research and development, and have already filed a patent application in 1983.
−186473 (JP-A No. 59-124507), No. 57-23741
The company has filed patent applications such as JP-A-58-143907 and JP-A-59-252697 (JP-A-61-131807).

The invention disclosed in Japanese Patent Application No. 57-23741 is equipped with a feed motor for advancing an electric drill toward a workpiece, and a control circuit of the electric drill is configured to control the magnitude of the load of the electric drill by controlling the current flowing therein. A detection unit is provided to detect based on the value, and when the detection output reaches the set level of the first stage, the feed of the electric drill is automatically stopped to reduce the load, and then the reduction in the load is detected. When this occurs, the feed of the electric drill is restarted, and when the second stage overload level is detected, both the rotation of the electric drill and the feed of the electric drill are automatically stopped, and the drilling is completed. At times, the rotation of the electric drill and the feeding of the electric drill are also automatically stopped.

Further, the invention of Japanese Patent Application No. 59-252697 includes a first detection circuit that stops the rotation of the feed motor when the load current flowing through the drill motor exceeds a first threshold; In addition to a second detection circuit that also stops the rotation of the drill motor when the second threshold is exceeded, the feed motor is intermittently activated when the load current is below the first threshold. We will take steps to stop the
The built-up cutting edge formed on the tool is easily removed and chips are discharged, and as a result, a large load is prevented from being applied to the electric drill.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

(1) If the feed motor is driven intermittently, the drilling efficiency will decrease accordingly.

(2) Conventionally, the rotational speed of the feed motor, and therefore the feed rate of the electric drill, was set to be almost constant, especially when the workpiece has a highly hard layer called "black scale" on its surface. In this case, the biting of the drill is poor at the initial stage of drilling, which may result in inaccurate or misaligned drilling positioning, and in severe cases, the drilling machine itself may be swung around.

The present invention has been made to solve the above-mentioned problems.

(Means and effects for solving the problem) In order to solve the above problem, the present invention provides a method in which the electric drill moves forward by a predetermined distance immediately after starting the electric drill, that is, in the initial stage of starting machining. During the interval or during the scheduled time from startup, the feed motor is driven by an AC half wave to bring it into a slow feed state, and after the initial stage has passed, the feed motor is driven by an AC full wave. On the other hand, the load current flowing through the drill motor is detected, and the drive current of the feed motor is controlled in feedback according to the magnitude of the detected load signal, so that the load signal increases and exceeds the second upper limit value. In this case, emergency stop both the feed motor and drill motor,
The present invention is characterized in that when drilling is finally completed, both the feed motor and the drill motor are stopped upon detecting that the drill motor is no-load and the load signal has suddenly decreased.

(Example) The present invention will be described in detail below with reference to the drawings, but before that, an outline of a drilling machine device suitable for applying the present invention will be described. FIG. 3 is a schematic perspective view showing the overall structure of a mechanical part suitable for applying the present invention, and FIG. 4 is a right side view thereof.

In these figures, 1 is a frame, 2 is an electromagnetic base attached to the bottom of frame 1, 3 is an electric drill installed on the front of frame 1 so that it can be raised and lowered either manually or electrically, and FM is electric drill 3. The feed motor 5 is an annular cutting tool attached to the arbor of the electric drill 3.

Further, 39 is a manual lifting/lowering operation handle for manually feeding the electric drill 3, and 36 is a manual lifting/lowering operation handle for manually feeding the electric drill 3.
It is a sliding plate fixed to the

The switch operation plate 37 is fixed to the slide plate 36 with thumbscrews 38. The switch operating plate 37 moves as the electric drill 3 descends, and when it descends to a predetermined position, it operates a limit switch S1 (described later with reference to FIG. 1).

40 is an operation handle for operating the start switch PS, which moves in two steps and
contacts 0, 1, and 2 (see FIG. 1) are turned on in a predetermined order.

An operation control circuit constituting the main part of the present invention is built into the frame 1. Also, punch 4
When positioning the electric drill, the spring 42, which has stored energy in advance, instantaneously descends and sticks to the surface of the workpiece, and in combination with the adsorption force of the electromagnetic base 2, which will be described later, ensures positioning. Make it.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a timing chart for explaining its operation.

A. Half-wave feed control of the feed motor FM immediately after startup When the power switch PS is in the "0" position, all power supplies are cut off and the drilling machine control device shown in FIG. 1 is in a dormant state.

When the power switch PS is moved to the "1" position, the electromagnetic magnesium MG is excited, and the electromagnetic base 2 of the electric drill is attracted to the workpiece, and positioning is performed. At the same time, the light emitting diode LED4 lights up to indicate that positioning is complete.

When the power switch PS is moved to the "2" position, the AC power supply voltage is applied to the primary winding of the step-down transformer T, so that the rectifiers REF2 and
REF3 operates and generates DC voltage.

The DC output of rectifier REF2 is a constant voltage device.
It is adjusted to a constant voltage by the STB and becomes the control voltage Vcc. The control voltage Vcc is connected to a resistor R6.
3 and the transistor Tr11.

As will be described in detail later, at this time, the base potential of the transistor Tr11, that is, the output of the OR circuit 3 and the charging voltage of the capacitor C13 are at a low level, so the transistor Tr11
is in an off state, and its collector potential is approximately equal to the control voltage Vcc.

Therefore, the control voltage Vcc is applied to the relay SSR.
is applied to the light emitting diode LED6, and the light emitting diode LED6 emits light. The light emission is applied to the triac TRC2, and the relay SSR becomes conductive. This energizes the drill motor ED and starts rotating.

The secondary voltage of the step-down transformer T is also subjected to half-wave rectification by the diode D4, and is supplied to the base of the transistor Tr8 via the resistor R36.

Therefore, the transistor Tr8 conducts at a period of every AC half wave, and the collector has the second
A pulse signal synchronized with an AC half wave as shown by waveform 2 in the figure is generated and supplied to one input terminal of the OR circuit OR1.

Note that, at this time, the operational amplifier OP6 does not generate an output, as will be explained later. For this reason, the output of the OR circuit OR1 becomes a pulse signal synchronized with an AC half wave as shown by waveform 2 in FIG.

On the other hand, the secondary voltage of the step-down transformer T is
Full-wave rectification is performed by REF3, and the rectified output is resistor R3.
4 and the zener diode ZD are added to the series circuit. Therefore, a pulse voltage that clips the full-wave rectified waveform at a predetermined level is generated across the zener diode ZD, as shown by waveform 3 in FIG. supplied to the base.

Transistor Tr6 has AC waveform 1 in FIG.
Since it is conductive except near the zero crossing point, its collector potential is as shown in waveform 4 in Figure 2,
The level is high near the zero-crossing point, and the level is low elsewhere.

Contrary to the transistor Tr6, the transistor Tr7 conducts near the zero-crossing point of the AC waveform 1 in FIG. becomes low level.

During the time when the collector of transistor Tr7 is at high level, capacitor C8 is connected to C8, R4.
It is charged with a time constant of 2, and when the transistor Tr7 becomes conductive, it is discharged through it with a very short time constant.

Therefore, the charging voltage of the capacitor C8, that is, the input voltage at the non-inverting input terminal of the operational amplifier OP7 changes in a sawtooth pattern as shown by the solid line of waveform 5 in FIG.

The load current flowing through the drill motor ED is detected by the current transformer CT and the rectifier and smoother RSC, and a load signal Eed is generated.

When the drill motor ED is first started, there is no load on the drill motor ED, so the load signal
Eed is small enough. Therefore, the op amp
The non-inverting input terminal of OP7 is larger than the inverting input terminal, and its high level output is connected to the AND circuit.
Supplied to AND1.

Therefore, the AND circuit AND1 is an OR circuit
The output of OR1, in other words, the same output as the collector potential of transistor Tr8 shown in waveform 2 in FIG. 2 is produced, and this is supplied to the gate of triac TRC1.

In this way, the feed motor FM is driven by a half-wave of the AC waveform, so that the electric drill is fed at a relatively slow speed. As a result, the electric drill's blade eventually reaches the surface of the workpiece, and drilling begins from the hard part, the so-called black crust.

When this drilling starts, the load current of the drill motor ED gradually increases, and the load signal Eed rises.

Therefore, operational amplifier OP7 produces a low level output during times when the level of the sawtooth signal applied to its non-inverting input terminal is low, and produces a high level output when the sawtooth signal exceeds the load signal Eed. I come to do it.

As is clear, the lower the load signal Eed, the earlier the high-level output occurs.
The higher the load signal Eed is, the slower it becomes.

For this purpose, the timing when the AND circuit AND1 is opened by the high level output of the operational amplifier OP7, in other words, the timing when the AND circuit AND1 is opened by the high level output of the operational amplifier OP7,
The phase in which AC voltage is applied to the feed motor FM after being triggered is earlier as the load signal Eed is lower, and slower as the load signal Eed is higher.

Therefore, the feed speed of the electric drill becomes faster as the load applied to the drill motor ED is lower, and conversely, as the load is higher, the feed speed becomes slower.

The load signal Eed is also the operational amplifier OP4
It is also supplied to the non-inverting input terminal of the resistor R16,
It is compared with a reference value divided by R17.

At the beginning of the start-up of the drill motor ED, the load is light, so the load signal Eed is small, the output of the operational amplifier OP4 is at a low level, the transistor Tr4 is conductive, and its collector is at a low level.

Therefore, capacitor C7 is not charged. That is, the terminal voltage of the capacitor C7 is at a low level, and the output of the inverter circuit IN2 is at a high level. The output of inverter circuit IN2 is connected to inverter circuit IN3 and AND circuit.
It is fed to the first input of AND2.

The low level signal inverted by the inverter circuit IN3 is sent to the second AND circuit AND2.
Since it is supplied as an input, the AND circuit AND
The output of 2 becomes low level. OR circuit OR
2. Since the output of OR3 maintains a low level and does not make transistor Tr11 conductive,
Relay SSR continues to operate. In this way, drill motor ED and feed motor FM continue to be driven.

B Transition of the feed motor FM from slow-speed feed to full-wave feed control Since the low-level charging voltage of capacitor C7 is also supplied to one terminal of NAND circuit NAN at the same time, its output is set to high level and transistor Tr5 is made non-conductive. Make it. At this time, the potential of the collector of transistor Tr5 is high level,
Capacitor C13 is charged via diode D2. Therefore, the output of the operational amplifier OP6 is at a low level, and does not affect the output of the OR circuit OR1.

The load on the drill motor ED increases and the load signal
When Eed further increases, the output of the operational amplifier OP4 is inverted and becomes a high level, and the transistor Tr4 is cut off. The collector of transistor Tr4 becomes high level, capacitor C7 is charged via resistors R20 and R22, and its terminal voltage increases. As a result, the inverter circuit
Since the output of IN2 falls to low level and the output of inverter circuit IN3 becomes high level,
Capacitor C12 begins to charge through resistor R60. However, in this case, the inverter circuit
Since the output of IN2 is low level, the output of the AND circuit AND2 does not change and the output of the OR circuit OR2
The subsequent state of the circuit remains unchanged.

On the other hand, the terminal voltage of the capacitor C7, which gradually increases as described above, is supplied to one input terminal of the NAND circuit NAN. At this stage, as described later, the output of operational amplifier OP5 does not change.
Since the high level is maintained, when the terminal voltage rises to a certain value (SH1) [see waveform 14 in FIG. 2], the output of the NAND circuit NAN is inverted and becomes low level. As a result, the transistor Tr5 becomes conductive, so the capacitor C1
The charging charge of 3 is diode D3, resistor R30,
and is discharged via transistor Tr5.
Note that the discharge time constant at this time is selected to be considerably large.

The non-inverting input terminal of the operational amplifier OP6 is supplied with the sawtooth wave voltage (points of waveform 5 and waveform 11 in Figure 2) generated at the terminal of the capacitor C8, while its inverting input terminal is supplied with the terminal of the capacitor C13. Voltage [solid line of waveform 11 in Figure 2]
is supplied.

Therefore, as shown by waveform 9 in FIG. 2, the output of the operational amplifier OP6 becomes high level only during the time when the terminal voltage of the capacitor C13 becomes larger than the sawtooth wave voltage of the capacitor C8.

Therefore, the output of the operational amplifier OP6 has a pulse waveform whose rise timing advances as the terminal voltage of the capacitor C13 decreases. This high-level output is supplied to the OR circuit OR1 and superimposed on the half-wave output from the transistor Tr8.

The superimposed waveform is applied to the triac TRC1 via the AND circuit AND1, making it conductive. Therefore, the feed motor FM gradually shifts from the initial half-wave drive to normal rapid feed, and the capacitor C
When the potential of the operational amplifier OP6 becomes sufficiently low, the output of the operational amplifier OP6 is almost always at a high level, so that a full-wave drive state is achieved.

In addition, in Fig. 1, rectifier REF3, Zener diode ZD, transistors Tr6, Tr
7, capacitor C8, and their associated resistors constitute a sawtooth voltage generation circuit, but those skilled in the art will recognize that they may be substituted with other suitable circuit elements and configurations.

Furthermore, the same sawtooth wave signal that is supplied to the non-inverting input terminal of operational amplifier OP7 is supplied to the non-inverting input terminal of operational amplifier OP6, but this is an AC half-wave signal generated at the collector of transistor Tr8. It may be an intermittent sawtooth wave signal that occurs only during the low level time of the pulse wave signal corresponding to .

C. Automatic control during full-wave drive sending A divided voltage by resistors R24 and R25 is supplied as the first overload reference voltage L1 to the non-inverting input terminal of the operational amplifier OP5. This first
The overload reference voltage L1 is set to a value smaller by a predetermined value than a second overload reference voltage L2 for completely stopping overload, which will be described later.

During drilling work on a workpiece, a large load is applied to the drill motor ED for some reason.
When the load signal Eed exceeds the first overload reference voltage L1, the output of the operational amplifier OP5 is inverted to low level, and the output of the NAND circuit NAN becomes high level.

Transistor Tr5 is cut off, and capacitor C13 is charged with an extremely short time constant. As the terminal voltage of capacitor C13 increases, the time during which operational amplifier OP6 generates a high level output decreases, as can be seen from the above description.

In other words, the duty ratio of the pulse generated from the operational amplifier OP6 decreases, its rising edge phase is delayed, and ultimately pulse generation disappears, so the drive current of the feed motor FM approaches half-wave, and the electric drill Feed speed decreases.

In this way, during the time when the feed motor FM is full-wave driven, the higher the load, the faster the trial drive will be performed depending on the load on the drill motor ED.
Since the trigger phase of TRC1 is delayed, the feed rate is small, and at the slowest speed, it is a slow feed by half-wave drive, and conversely, the smaller the load is, the more the trigger phase of triax TRC1 is advanced, so the feed rate is controlled to be large. Ru.

D Full stop control during overload The divided voltage by resistors R55 and R56 is supplied as the second overload reference voltage L2 to the inverting input terminal of the operational amplifier OP8. When the load on the drill motor ED becomes larger than the limit and the load signal Eed exceeds the second overload reference voltage L2, the output of the operational amplifier OP8 is inverted and becomes a high level.

This high level signal is sent to the AND circuit AND3.
Transistor via OR circuit OR2, OR3
When applied to the base of Tr11, transistor Tr11 becomes conductive and its collector potential drops to a low level. This de-energizes relay SSR, which de-energizes drill motor ED and feed motor.
FM will be stopped together.

Generally, a large rush current flows when the motor is started, and there is a risk that the load signal Eed at this time exceeds the second overload reference voltage L2, so the above-mentioned full stop control operation must be prohibited at the time of starting.

For this purpose, resistor R58 and capacitor C
A time constant (integration) circuit consisting of 11 and an AND circuit AND3 are attached to the output side of the operational amplifier OP8.

At the same time that the power switch PS is set to the "2" position and the motor is started, the capacitor C11 is charged by the control voltage Vcc via the resistor R58. However, since the terminal voltage of the capacitor C11 is less than the scheduled value during the scheduled time after activation, the AND circuit AND3 is closed.

Therefore, even if the load signal Eed at startup becomes excessive and the operational amplifier OP8 produces an output, this output will pass through the AND circuit AND3 and the OR circuits OR2 and OR3 to the transistor Tr1.
It will no longer affect the state of 1.

When the scheduled time elapses, the capacitor C1
1 terminal voltage increases, AND circuit AND3
is opened, the output of operational amplifier OP8 is no longer blocked, and the drill motor operates normally.
ED overload protection is provided.

In addition, the switch S1, which is connected to short-circuit the resistor R56 on the inverting input terminal side of the operational amplifier OP8, is independent of whether the drilling operation is completed or not when the electric drill moves forward toward the workpiece to the maximum limit. It is a limit switch that is closed when the

When switch S1 is closed, the operational amplifier
The output of OP8 operates in the same way as in the case of overload described above, and the output of drill motor ED and feed motor FM
A total cessation of the total is achieved.

E Full stop control when drilling is completed When drilling of the workpiece is completed, the drill motor
Since the ED is almost in a no-load state, the load signal
Eed decreases rapidly.

As a result, the output of operational amplifier OP4 becomes low level, transistor Tr4 becomes conductive, and
Capacitor C7 is diode D1, resistor R21
and is discharged via transistor Tr4.
The output of the inverter circuit IN2 is inverted to a high level, and this is transmitted to one input of the AND circuit AND2.

At this time, as described above, the capacitor C
12 is charged and its terminal voltage is at a high level, so the output of the AND circuit AND2 becomes a high level, and this signal is sent to the OR circuit OR.
2, applied to the base of the transistor Tr11 via OR3, making it conductive.

Therefore, the collector of transistor Tr11 falls to low level, and the light emitting diode
LED6 is turned off, relay SSR is disconnected,
Drill motor ED and feed motor FM both stop.

Since the output of OR circuit OR3 is fed back to its input, OR circuit OR3 is self-maintained,
Its output maintains a high level.

In addition, the light emitting diode LED connected to the collector-emitter circuit of transistor Tr13
Reference numeral 5 denotes an indicator light indicating a non-operating state of the relay SSR, that is, a stopped state of the drill motor ED and the feed motor FM, and lights up when the drill motor ED and the feed motor FM are stopped.

Note that the completion of drilling can also be detected by monitoring the differential value of the load signal Eed and when it exceeds the negative predetermined value, so this detection output can be used instead of the output of the AND circuit AND2. It is clear that it may be used for

F Load status display Load signal Eed is also operational amplifier OP1~OP
It is also supplied to each of the three non-inverting input terminals. Each inverting input terminal of the operational amplifiers OP1 to OP3 has a
Reference voltage E divided by resistors R4 to R9
1 to E3 are applied.

Now, assuming that there is a relationship of E1<E2<E3 between the reference voltages E1 to E3, the drill motor ED
When the load is at its lightest, the operational amplifier OP1 produces an output, the corresponding transistor Tr1 becomes conductive, and the light emitting diode LED1 lights up.

As the load increases step by step, the op amp
OP2 and OP3 sequentially generate outputs, and the light emitting diodes LED2 and LED3 are sequentially lit. In this way, the light emitting diodes LED1 to LED3
You can tell whether the drill motor ED is under light load, normal load, or heavy load by looking at the lighting state of .

The above describes an example in which the present invention is implemented using hard logic by combining individual logic elements, but as is clear to those skilled in the art, the present invention can also be implemented using soft logic (software) using a computer. You can also do it.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) At the start of drilling, the feed motor is driven in half-wave,
Since the feed speed of the electric drill is extremely low,
It ensures that it penetrates into the hard part (black scale) of the workpiece surface, and performs highly accurate drilling.
There is no risk of the drilling machine swinging around due to overload.

(2) After drilling the black skin, the drive of the feed motor is gradually switched from half-wave to full-wave and the feed speed increases, so drilling should be performed at the highest efficiency that matches the performance of the electric drill. I can do it.

(3) Optimal feed rate control is achieved according to the load of the drill motor, so the size (diameter) of the annular cutter
can be selected from a wide range.

(4) In all processes of drilling work, the drill motor
Since the optimum and highest feed rate control is achieved according to the load of the ED, the highest work efficiency is achieved without causing the drilling machine to swing around. Therefore, a relatively small drill motor can be used to perform high-load, in other words, large-diameter drilling.
It can be done safely and with high efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a time chart for explaining its operation, and Fig. 3 is a schematic diagram showing the overall configuration of mechanical parts suitable for applying the present invention. The perspective view and FIG. 4 are the right side drawings. ED...Drill motor, FM...Feed motor,
MG...electromagnetic magnet, PS...power switch,
RSC... Rectifier and smoothing device, SSR... Relay, STB
... Constant voltage device, TRC ... Triack.

Claims (1)

[Scope of Claims] 1. A control device for a drilling machine, comprising: an electric drill separately having a drill motor connected to an alternating current and a feed control motor; and an electromagnetic base fixing the electric drill to a workpiece. , switching means for controlling power supply to the feed control motor; means for detecting a load signal representing a load current of the drill motor; and means for generating a sawtooth wave signal having a frequency twice the frequency of the AC power supply. , means for generating a first pulse corresponding to a half wave of the AC power supply; means for generating a second pulse that is synchronized with the sawtooth wave signal and whose duty ratio increases as the load signal decreases; A control device for a drilling machine that can be fixed to a workpiece on an electromagnetic basis, comprising means for controlling the timing of applying an alternating current voltage to a feed control motor according to the logical product of the first and second pulses. . 2. A control device for a drilling machine comprising an electric drill separately having a drill motor connected to an alternating current and a feed control motor, and an electromagnetic base for fixing the electric drill to a workpiece, the control device comprising: a drill motor connected to an alternating current and a feed control motor; switching means for controlling power supply to the drill motor; means for detecting a load signal representative of the load current of the drill motor; means for generating a sawtooth wave signal having a frequency twice the frequency of the AC power supply; means for generating a first pulse corresponding to a wave; means for generating a second pulse that is synchronized with the sawtooth wave signal and whose duty ratio increases as the load signal decreases; During the half-wave period,
means for generating a third pulse whose duty ratio increases as time elapses from the start of the drill motor; an OR circuit for calculating the logical sum of the first and third pulses; and the logical sum and the second pulse. means for controlling the timing of applying an alternating current voltage to the feed control motor according to the logical product of 1. A control device for a drilling machine that can be fixed to a workpiece using an electromagnetic base, and comprising means for controlling the duty ratio to be small. 3. A control device for a drilling machine that can be fixed to a workpiece using an electromagnetic base according to claim 2, wherein the first pulse and the third pulse are synchronized with the voltage waveform of an AC power source. 4. Control of a drilling machine that can be fixed to a workpiece using an electromagnetic base according to claim 2 or 3, wherein the duty ratio of the third pulse varies between 0 and 1. Device. 5. The duty ratio of the third pulse is controlled by advancing or delaying the rising timing of the leading edge of the third pulse. Drilling machine control device.