CN212600991U

CN212600991U - Safety protection device for handheld polishing machine and handheld polishing machine

Info

Publication number: CN212600991U
Application number: CN202020273763.4U
Authority: CN
Inventors: 甘世杰
Original assignee: Shenzhen Deep Combustion Gas Technology Research Institute; Shenzhen Gas Corp Ltd
Current assignee: Shenzhen Deep Combustion Gas Technology Research Institute; Shenzhen Gas Corp Ltd
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-02-26
Anticipated expiration: 2030-03-06

Abstract

The utility model discloses a safety protection device for a hand-held polishing machine and the hand-held polishing machine, which comprises an index finger pressure-sensitive element and a first analog-to-digital conversion module, wherein the index finger pressure-sensitive element is arranged on one side of a holding position of the hand-held polishing machine; the thumb pressure-sensitive element is arranged on the other side of the handheld position of the handheld polishing machine, and the second analog-to-digital conversion module is arranged on the other side of the handheld polishing machine; the holding posture operation relay is electrically connected with the misoperation statistical circuit and is used for counting the times of signals sent by the holding posture operation relay and turning off the motor after the times of the signals reach the preset times; the first analog-to-digital conversion module and the second analog-to-digital conversion module are connected with the holding posture operation relay in parallel, and a normally closed contact of the second analog-to-digital conversion module and a normally closed contact of the first analog-to-digital conversion module are sequentially connected in series on a parallel branch of the holding posture operation relay. Thereby detect the pressure of thumb and forefinger and shut off the motor through the number of times that detects to be less than the pressure standard, stop to polish, prevent like this to hold untight the polishing chance for a long time and lead to the operation in-process to appear unusually taking off the hand.

Description

Safety protection device for handheld polishing machine and handheld polishing machine

Technical Field

The utility model relates to a buffing machine part field especially relates to a safety arrangement and handheld buffing machine for handing buffing machine.

Background

At present, the existing hand-held polishing machines adopt manual mechanical switches to control the on-off of a power supply, so as to realize the starting or stopping of the hand-held polishing machines. When an operator operates the handheld polisher in the operation process due to the reasons of environment, personal factors and the like, the polisher is not operated according to the standard requirement, namely the polisher is not held tightly in the standard posture for operation, so that the handheld polisher is not held tightly, abnormal hand release occurs in the operation process due to the long-time holding and not-tight polishing, and unsafe risk exists.

Accordingly, the prior art is yet to be improved and developed.

SUMMERY OF THE UTILITY MODEL

In view of above-mentioned prior art not enough, the utility model aims to provide a safety arrangement and handheld buffing machine for handheld buffing machine, protect handheld polisher operating personnel, thumb pressure sensitive element through setting up the forefinger pressure sensitive element of one side and setting up opposite side on handheld position of handheld buffing machine, thereby fix a position handheld posture to the user on handheld position, in the time of the lack of standardization, thereby can detect the pressure of thumb and forefinger and close the motor through the number of times that detects to be less than the pressure standard, stop polishing, prevent like this to hold not tightly the polishing opportunity for a long time and lead to the operation in-process unusual the taking off the hand.

The technical scheme of the utility model as follows:

a safety guard for a hand sander including a main circuit for controlling a motor, the safety guard further comprising:

the first analog-to-digital conversion module is used for electrically connecting the index finger pressure-sensitive element and the index finger pressure-sensitive element arranged on one side of a handheld position of the handheld polishing machine;

the second analog-to-digital conversion module is electrically connected with the thumb pressure sensitive element;

the holding posture operation relay is electrically connected with the holding posture operation relay and is used for counting the misoperation counting circuit of the motor which is closed after the number of times of the signal sent by the holding posture operation relay reaches the preset number of times;

the first analog-to-digital conversion module and the second analog-to-digital conversion module are connected with the holding posture operation relay in parallel, and a normally closed contact of the second analog-to-digital conversion module and a normally closed contact of the first analog-to-digital conversion module are sequentially connected in series on a parallel branch of the holding posture operation relay.

The pressure operation mode selection switch comprises a first selection switch arranged on a parallel branch of the holding posture operation relay and a second selection switch arranged on the main circuit, and the first selection switch and the second selection switch are linked switches;

the first selection switch is arranged on a branch circuit where the second analog-to-digital conversion module normally-closed contact, the first analog-to-digital conversion module normally-closed contact and the holding posture operation relay are located, and the second contact of the first selection switch is connected with the second analog-to-digital conversion module normally-closed contact;

a first contact of the first selector switch is connected with a normally open contact of a second analog-to-digital conversion module and a pressure operation relay in series, a lead is connected between the first contact of the first selector switch and the normally open contact of the second analog-to-digital conversion module, the other end of the lead is connected between the normally closed contact of the first analog-to-digital conversion module and the normally closed contact of the second analog-to-digital conversion module, and a branch where the normally open contact of the second analog-to-digital conversion module and the pressure operation relay are located is connected with a branch where the normally closed contact of the first analog-to-digital conversion;

a first contact of the second selector switch is connected in series with a normally open contact of a pressure operation relay, and the normally open contact of the pressure operation relay is connected to the main circuit; and a second contact of the second selector switch is connected to the main circuit, and a branch where the second contact of the second selector switch is located is connected in parallel with a branch where the first contact of the second selector switch is located.

Further, the malfunction statistic circuit includes:

the counter is electrically connected with the holding posture operation relay and is connected to the main circuit in parallel;

the single time relay is connected with the counter in parallel and is electrically connected with the counter;

the counting normally closed first contact is positioned between the single time relay and the motor and is connected with the motor in series, and the counting normally open second contact is connected with the single time relay in series;

the counter is disconnected with the counting normally closed first contact when reaching the preset times, the counting normally open second contact is opened, and the single time relay counts the time to the preset time and sends information to enable the counter to return to the original position.

Further, the main circuit comprises a power supply, and an accumulated time statistic circuit connected to the power supply; the cumulative time statistic circuit comprises:

the motor is connected with the power supply through a motor shaft, and the motor is connected with the power supply through a motor shaft;

and the accumulated time timer is switched off when reaching the set time, and the normally closed contact for timing the accumulated time is closed.

Further, a continuous operation time statistical circuit between the accumulated time statistical circuit and the motor is connected to the main circuit, and the continuous operation time statistical circuit comprises a continuous time timer arranged in parallel with the motor, a rest time timer arranged in parallel with the continuous time timer and electrically connected with the continuous time timer, a continuous time timing normally closed contact arranged in series with the motor, and a continuous time timing normally open contact arranged in series with the rest time timer;

and the continuous time timer is disconnected from the continuous time timing normally closed contact when reaching the preset time and is communicated with the continuous time timing normally open contact, and the rest time timer sends a signal to the continuous time timer to reset after reaching the preset time.

Furthermore, the polishing machine also comprises a brake module which is arranged at the polishing part of the polishing machine and used for stopping the motor.

Furthermore, the brake module comprises a brake switch and a brake component electrically connected with the brake switch; the brake switch is used for starting the brake assembly when the misoperation statistical circuit cuts off the power supply of the motor.

Furthermore, the brake assembly comprises a film fixedly connected to an output shaft of the motor and an electromagnetic push rod fixedly arranged on a shell of the hand-held polishing machine, and the electromagnetic push rod is controlled by a brake switch to press or release the film.

Furthermore, the brake module comprises a rotary disc fixedly connected to an output shaft of the motor, a brake disc fixedly arranged on the shell of the hand-held polishing machine, and an elastic sheet with one end fixed to the edge of the rotary disc and the other end abutted to the edge of the brake disc.

A hand sander including a safety shield as described above for a hand sander.

Compared with the prior art, the utility model provides a safety arrangement and handheld buffing machine for handheld buffing machine, adopt the forefinger pressure sensitive element who sets up one side and set up the thumb pressure sensitive element of opposite side on the handheld position of handheld buffing machine in this scheme to fix a position the handheld posture of user on the handheld position, when using nonstandard, the pressure of thumb or forefinger can diminish, even the power that the user gripped the handheld position diminishes, when detecting that the pressure of thumb and forefinger is less than the setting value, second analog-to-digital conversion module normally closed contact and first analog-to-digital conversion module normally closed contact are closed, the signal number of times that holding posture operation relay sent arrives maloperation statistical circuit, the motor is closed after the maloperation statistical circuit reaches the preset number of times, stop polishing, prevent like this and hold untight polishing chance and lead to the operation in-process appearance unusual hands-off, protecting the user.

Drawings

Figure 1 is a functional block diagram of an embodiment of a safety shield for a hand sander according to the present invention;

fig. 2 is a schematic circuit diagram of a safety device for a hand sander according to the present invention;

fig. 3 is a schematic diagram of a main circuit of a safety protection device for a hand-held grinder according to the present invention;

figure 4 is a schematic diagram of a pressure control circuit for a safety guard of a hand sander according to the present invention;

fig. 5 is a schematic circuit diagram of a brake module of a safety device for a hand sander according to the present invention;

figure 6 is a side view of one form of a brake module for a safety shield of a hand sander according to the present invention;

figure 7 is a side view of another form of a brake module for a safety shield of a hand sander according to the present invention;

figure 8 is a front elevational view of another form of a brake module for a safety shield of a hand sander according to the present invention.

The reference numbers in the figures: 100. a motor; 200. an accumulated time statistic circuit; 210. an accumulated time timer; 220. normally closed contacts are timed according to accumulated time; 300. a malfunction statistics circuit; 310. a counter; 320. a single time relay; 330. counting the normally closed first contact; 340. counting the normally open second contact; 400. a pressure control circuit; 410. an index finger pressure sensitive element; 420. a first analog-to-digital conversion module; 421. a normally closed contact of the first analog-to-digital conversion module; 430. a thumb pressure sensitive element; 440. a second analog-to-digital conversion module; 441. a normally closed contact of the second analog-to-digital conversion module; 442. a normally open contact of the second analog-to-digital conversion module; 450. holding posture operation relay; 460. a first selection switch; 461. a first selector switch first contact; 462. a first selector switch second contact; 470. a second selection switch; 471. a second selector switch first contact; 472. a second selector switch second contact; 480. a pressure operated relay; 481. a normally open contact of a pressure operated relay; 500. a continuous run time statistics circuit; 510. a continuous time timer; 511. a continuous time timing normally closed contact; 512. a normally open contact is timed continuously; 520. a rest time timer; 600. a brake module; 610. a brake switch; 620. a brake assembly; 621. a film; 622. an electromagnetic push rod; 623. a spring; 630. An accumulative timing normally closed contact; 640. counting the normally closed second contact; 650. continuously timing a normally closed contact; 660. a turntable; 670. a brake disc; 680. a spring plate; 690. and (5) grinding.

Detailed Description

The utility model provides a safety arrangement and handheld buffing machine for handing buffing machine, for making the utility model discloses a purpose, technical scheme and effect are clearer, more clear and definite, and it is right that the following refers to the drawing and lifts the example the utility model discloses further detailed description. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The existing hand-held polisher only controls polishing by turning on or off a switch of a motor, and has the following problems in use. When the operator uses the hand-held polisher, the operator may not operate the polisher according to the specification or hold the polisher in the specified posture for operation due to the environment, personal factors, and the like, which may cause unsafe risks. The time of part of the polishing process is long, and the operators can easily neglect or pay attention to fatigue operation to cause accidents by holding the vibrating polishing machine for a long time.

The utility model provides a safety protection device for a hand-held polishing machine, as shown in figure 1, an accumulated time statistical circuit 200, a misoperation statistical circuit 300 and a continuous operation time statistical circuit 500 are connected between the power supply of a main circuit and a motor 100 in sequence; the cumulative time counting circuit 200 is used for cutting off a downstream circuit of the cumulative time counting circuit 200 when the preset time is timed out, so that the motor 100 stops, and a user is forced to rest for a period of time. The misoperation statistical circuit 300 is connected with a pressure control circuit 400, the pressure control circuit 400 detects the grip strength of a user, when the grip strength of the user does not reach the preset grip strength, the pressure control circuit 400 sends a signal to the misoperation statistical circuit 300, when the misoperation statistical circuit 300 reaches the preset times, the subsequent circuit of the misoperation statistical circuit 300 on the main circuit is cut off to stop the motor 100, so that abnormal hand drop in the operation process caused by the fact that the user does not hold the polisher tightly for a long time is prevented, and the user is protected. The continuous run time statistics circuit 500 is used to suspend the motor 100 for a period of time after it is turned on, which allows the user to be highly concentrated on working during the period of time that the motor 100 is turned on, and avoids safety problems caused by the user's lack of concentration during the operation of the hand sander.

As shown in fig. 2 and fig. 3, the specific circuit principle of the present invention is: the main circuit comprises a power supply, and a cumulative time statistic circuit 200 connected to the power supply, wherein the cumulative time statistic circuit 200 comprises: an accumulated time timer 210 connected in parallel with the motor 100, and an accumulated time timing normally closed contact 220 located between the accumulated time timer 210 and the motor 100 and connected in series with the motor 100; the cumulative time timer 210 opens the cumulative time timer normally closed contact 220 after reaching the set time. The general mental working time of an adult is about 60 minutes, when the power switch of the hand-held polishing machine is closed, the accumulated time timer 210 counts 60 minutes, the normally closed contact 220 for counting the accumulated time is cut off after the counted time is over 60 minutes, the power of the motor 100 is cut off until the power switch is turned on again, and the accumulated time timer 210 is reset, so that the operator is forced to rest. The preset time of the accumulation time timer 210 may be set according to a demand.

As shown in fig. 3 and 4, the malfunction statistics circuit 300 includes: a counter 310 connected downstream of the cumulative time statistic circuit 200 and arranged in parallel with the motor 100, the counter 310 being electrically connected to the pressure control circuit 400 and receiving the signal of the pressure control circuit 400, a single time relay 320 arranged in parallel with the counter 310, the single time relay 320 being electrically connected to the counter 310; a counting normally closed first contact 330 which is positioned between the single time relay and the motor 100 and is connected with the motor 100 in series, and a counting normally open second contact 340 which is connected with the single time relay in series; the counter 310 counts the signals sent by the pressure control circuit 400, and when the preset counting times are reached, the counter is controlled to be turned off to normally close the first contact 330, so that the downstream power is cut off, the power supply of the motor 100 is cut off, and the motor 100 stops; meanwhile, the counter 310 starts to count the normally open second contact 340, the single time relay 320 is electrified, and the single time relay 320 counts the preset time to send a signal to reset the counter 310. Thus, when the pressure control circuit 400 sends a signal for 3 times due to small hand-held pressure, and accumulates and counts the signal with small hand-held pressure for three times, the motor 100 stops, the single time relay 320 runs for 3 minutes, the counter 310 resets after 3 minutes, and the motor 100 starts.

As shown in fig. 4, the pressure control circuit 400 includes: the first analog-to-digital conversion module 420 is electrically connected with the index finger pressure sensitive element 410; the thumb pressure sensitive element 430 is arranged on the other side of the handheld position of the handheld polishing machine, and the second analog-to-digital conversion module 440 is electrically connected with the thumb pressure sensitive element 430; the thumb pressure sensitive element 430 and the index pressure sensitive element 410 can be non-contact or contact type switch elements such as light-sensitive, capacitance, inductance and the like. The holding posture operation relay 450 is connected in parallel with the first analog-to-digital conversion module 420 and the second analog-to-digital conversion module 440, the holding posture operation relay 450 is electrically connected with the misoperation statistical circuit 300, and the holding posture operation relay 450 is used for sending a signal to the misoperation statistical circuit 300. A second analog-to-digital conversion module normally-closed contact 441 and a first analog-to-digital conversion module normally-closed contact 421 are sequentially connected in series on a parallel branch of the holding posture operation relay 450.

When the holding posture operation relay 450, the first analog-to-digital conversion module 420 and the second analog-to-digital conversion module 440 are connected in parallel to form a loop, when a user holds the handheld sander to operate, the thumb pressure sensitive element 430 and the index pressure sensitive element 410 sense pressure, the first analog-to-digital conversion module 420 converts an analog signal of the index pressure sensitive element 410 into an electric signal, when the pressure of the index pressure sensitive element 410 is sensed to be greater than a set value, namely 2kg, the first analog-to-digital conversion module 420 is in a power-on starting state, the normally closed contact 421 of the first analog-to-digital conversion module is disconnected, the holding posture operation relay 450 is not powered, and a frequency signal is not sent; when the pressure of the index finger pressure-sensitive element 410 is sensed to be less than 2kg, the first analog-to-digital conversion module 420 is in a power-off state, and the normally-closed contact 421 of the first analog-to-digital conversion module is closed; the second analog-to-digital conversion module 440 and the first analog-to-digital conversion module 420 have the same control principle, so that when the user does not operate according to the C-type grip posture or the grip strength is insufficient, the thumb pressure-sensitive element 430 and the index pressure-sensitive element 410 sense that the pressure is less than the set value, namely 2kg, the first analog-to-digital conversion module normally closed contact 421 and the second analog-to-digital conversion module normally closed contact 441 are closed and communicated, the grip posture operation relay 450 is powered on to send a one-time non-grip signal, and the grip posture operation relay 450 is electrically connected with the counter 310 in the misoperation statistical circuit 300; when a user grips the hand-held grinder, the first analog-to-digital conversion module 420 and the second analog-to-digital conversion module 440 are in an energized state, the first analog-to-digital conversion module normally-closed contact 421 and the second analog-to-digital conversion module normally-closed contact 441 are in an open state, and the grip posture operation relay 450 is de-energized and does not send a signal. After three signals are sent, indicating that the user has not gripped the hand sander three times, the malfunction statistics circuit 300 is enabled and the motor 100 is disabled.

Adopt in this scheme to set up forefinger pressure-sensitive element 410 of one side and set up thumb pressure-sensitive element 430 of opposite side on the handheld position of handheld buffing machine, thereby fix a position user's handheld posture on the handheld position, when using the nonstandard, the pressure of thumb or forefinger can diminish, namely the power that the user gripped the handheld position diminishes, when the pressure that detects thumb and forefinger is less than the setting value, second analog-to-digital conversion module normally closed contact 441 and first analog-to-digital conversion module normally closed contact 421 close, the signal number of times of holding posture operation relay 450 transmission is to maloperation statistical circuit 300, maloperation statistical circuit 300 closes motor 100 after reaching preset number of times, stop polishing, prevent like this to hold untight polishing chance and lead to the unusual release of hand in the operation process for a long time, protect the user.

In this embodiment, mode selection can be realized, specifically, the pressure control circuit 400 further includes a pressure operation mode selection switch, where the pressure operation mode selection switch includes a first selection switch 460 disposed on a parallel branch of the holding posture operation relay 450, and a second selection switch 470 disposed on the main circuit, and the first selection switch 460 and the second selection switch 470 are linked switches; that is, when the first selection switch 460 is connected to the first selection switch first contact 461, the second selection switch 470 is connected to the second selection switch first contact 471; when the first selection switch 460 is connected to the first selection switch second contact 462, the second selection switch 470 is connected to the second selection switch second contact 472.

The first selection switch 460 is arranged on a branch where the second analog-to-digital conversion module normally-closed contact 441, the first analog-to-digital conversion module normally-closed contact 421 and the holding posture operation relay 450 are located, and the first selection switch second contact 462 is connected with the second analog-to-digital conversion module normally-closed contact 441; the first contact 461 of the first selector switch is connected in series with a second analog-to-digital conversion module normally-open contact 442 and a pressure-operated relay 480, a lead is connected between the first contact 461 of the first selector switch and the second analog-to-digital conversion module normally-open contact 442, the other end of the lead is connected between the first analog-to-digital conversion module normally-closed contact 421 and the second analog-to-digital conversion module normally-closed contact 421, and a branch where the second analog-to-digital conversion module normally-open contact 442 and the pressure-operated relay 480 are located is connected in parallel with a branch where the first analog-to-digital conversion module normally-closed contact 421 and the holding-.

The first contact 471 of the second selector switch is connected in series with a normally open contact 481 of the pressure-operated relay, and the normally open contact 481 of the pressure-operated relay is connected to the main circuit; the second selection switch second contact 472 is connected to the main circuit, and the branch where the second selection switch second contact 472 is located is arranged in parallel with the branch where the second selection switch first contact 471 is located.

Thus, two functions are realized through the linkage arrangement of the first selection switch 460 and the second selection switch 470: when the first selection switch 460 is connected to the first selection switch first contact 461, the second selection switch 470 is connected to the second selection switch first contact 471, the motor 100 is operated by the pressure of the thumb pressure sensitive element in the pressure operation mode, and the index finger pressure sensitive element detects the fatigue times. Taking the grip strength as an example for illustration, when the pressure of the index finger pressure sensitive element 410 and the thumb pressure sensitive element 430 is insufficient, the first analog-to-digital conversion module 420 and the second analog-to-digital conversion module 440 are in a power-off state, the normally closed contact 421 of the first analog-to-digital conversion module is closed and communicated, the grip posture operation relay 450 sends a pressure deficiency signal for counting, and the normally open contact 442 of the second analog-to-digital conversion module is opened, so that the pressure operation relay 480 is powered off, the normally open contact 481 of the pressure operation relay is opened, the motor 100 is powered off and stops rotating, so that the pressure operation motor 100 of the big thumb is started or suspended, the pressure sensitive element of the index finger detects the fatigue times, and when the hand-held sander is out of hand, the thumb is separated from the thumb.

In another form, when the first selection switch 460 is in communication with the first selection switch second contact 462, the second selection switch 470 is in communication with the second selection switch second contact 472, and both the thumb pressure sensitive element and the index pressure sensitive element detect the fatigue count; taking the grip strength as an example for illustration, when the pressure of the index finger pressure sensitive element 410 and the pressure of the thumb pressure sensitive element 430 are insufficient, the first analog-to-digital conversion module 420 and the second analog-to-digital conversion module 440 are both in a power-off state, so that the normally closed contact 421 of the first analog-to-digital conversion module and the normally closed contact 441 of the second analog-to-digital conversion module are both communicated, and the grip posture operation relay 450 sends a pressure insufficiency signal for counting after being powered on. Thereby realizing that the thumb pressure sensitive element and the forefinger pressure sensitive element both detect the fatigue times.

The working voltage of the pressure control circuit 400 is direct current 5V, which meets the safety requirements of the hand-held electric tool.

As shown in fig. 2 and 3, a continuous operation time statistic circuit 500 is connected to the main circuit and located between the cumulative time statistic circuit 200 and the motor 100, and specifically, the continuous operation time statistic circuit 500 is located downstream of the malfunction statistic circuit 300, and the continuous operation time statistic circuit 500 includes a continuous time timer 510 connected in parallel with the motor 100, a rest time timer 520 connected in parallel with the continuous time timer 510 and electrically connected to the continuous time timer 510, a continuous time counting normally closed contact 511 connected in series with the motor 100, and a continuous time counting normally open contact 512 connected in series with the rest time timer 520; the continuous time timer 510 is disconnected from the continuous time normally closed contact 511 when reaching a preset time, and is connected to the continuous time normally open contact 512, and the rest time timer 520 sends a signal to the continuous time timer 510 to reset when reaching the preset time. The typical adult high concentration continuous time is about 10 minutes, so the hand sander pauses for 15 seconds when running continuously for 10 minutes; that is, the preset time of the continuous time timer 510 may be 10 minutes, the preset time of the rest time timer 520 may be 15 seconds, when the operating time of the motor 100 reaches 10 minutes, the continuous time timer 510 is started, the continuous time timing normally closed contact 511 is powered off to power off the motor 100, and the continuous time timing normally open contact 512 is connected to power on the rest time timer 520, and the rest time timer 520 is reset by sending a signal to the continuous time timer 510 for 15 seconds.

The safety protection device also comprises a brake module 600 which is arranged at the grinding part of the polishing machine and used for stopping the motor 100. When the motor 100 is powered off, the grinding sheet 690 can continue to rotate due to inertia, and thus certain potential safety hazards exist, and the braking module 600 can be adopted to enable the grinding sheet 690 to stop rotating quickly after the power is off.

The brake module 600 in this embodiment includes two types, and in actual use, the two types may be used separately or simultaneously. As shown in fig. 5, one form is: the brake module 600 includes a brake switch 610, a brake component 620 electrically connected to the brake switch 610; the brake switch 610 is used for activating the brake assembly 620 when the malfunction statistic circuit 300 disconnects the power supply of the motor 100. Specifically, a branch is connected to the main circuit, a brake switch 610 is arranged on the branch, and the brake switch 610 comprises an accumulative timing normally-closed contact 630, a counting normally-closed second contact 640 and a continuous timing normally-closed contact 650 which are sequentially connected in series; the accumulation time normally closed contact 630 opens the circuit when the accumulation time timer 210 reaches a preset time, the counting normally closed second contact 640 opens the circuit when the counter 310 reaches a preset counting number, and the continuous time normally closed contact 650 opens the circuit when the continuous time timer 510 reaches a preset time. When one of the misoperation statistical circuit 300, the accumulated time statistical circuit 200 or the continuous operation time statistical circuit 500 cuts off the power supply of the motor 100, the brake switch 610 works and cuts off the power supply of the brake assembly 620, and the brake assembly 620 abuts against the grinding sheet 690 after no electric energy exists, so that the grinding sheet 690 brakes.

As shown in fig. 6, the brake assembly 620 includes a film 621 fixedly connected to the output shaft of the motor 100, and an electromagnetic push rod 622 fixedly disposed on the housing of the hand-held grinder, wherein the electromagnetic push rod 622 is controlled by the brake circuit to press or release the film 621. The device also comprises a spring 623, when the electromagnetic push rod 622 is electrified, the push rod compresses the spring 623 and is far away from the film 621, when the electromagnetic push rod 622 is not electrified, the spring 623 pushes the push rod to contact the film 621, so that the push rod is pressed against the film 621, and the brake is realized.

As shown in fig. 7 and 8, another form is: the brake module 600 includes a turntable 660 fixedly connected to the output shaft of the motor 100, a brake disc 670 fixedly disposed on the housing of the hand-held polishing machine, and a resilient plate 680 having one end fixed to the edge of the turntable 660 and the other end abutting against the edge of the brake disc 670. The motor 100 is because of centrifugal power when rotatory, and the shell fragment 680 is close to the outside expansion of one end of brake disc 670, and the shell fragment 680 descends because of the rotational speed during the outage, and the inward shrink of shell fragment 680 contacts the brake disc 670, forms the increase-up circulation that the braking is accelerated, realizes the quick braking of abrasive disc 690 and stops. The kinetic energy of the idle running of the hand sander after power off is reduced by the brake module 600 and the brake is applied within 3-8 seconds, which is faster than a 10-60 second natural stop without this function.

The scheme also provides a polishing machine, wherein the polishing machine comprises the safety protection device for the handheld polishing machine. The housing of the hand-held polisher with the pressure-sensitive element is manufactured and comprises a housing designed to be suitable for the holding posture of the left hand or the right hand. Two pressure sensitive elements are no less than to set up on the shell, and small-size handheld buffing machine sets up forefinger position and big finger position, and the middle finger position is add to large-scale handheld buffing machine, and more pressure sensitive elements are add to the handheld buffing machine of both hands operation. The installation position of the pressure sensitive element accords with the ergonomic design and can be held for a long time. The C-grip position covers more than one-half of the handle of the hand sander while ensuring that the hand sander is gripped with a force sufficient to meet ergonomic design for long-term holding. According to the control principle, the pause and the start of the hand-held polisher can be controlled by the grip force of one finger, so that the polisher can be controlled more conveniently, for example, a large mother finger is shifted from a grip point. The current commonly used hand-held polishing machine is 100 type (i.e. the diameter of the grinding sheet 690 is 100mm), and 2kg of holding force is measured to be proper and can be held for a long time. The higher grip force can be adjusted in working environments with falling risks such as high-altitude operation and the like so as to ensure the safety of operation; the single or continuous operation time and the pause time can be adjusted in limited space environments such as underground operation and the like to prevent the risk of poisoning or oxygen deficiency; the number of times of preventing counting can be properly enlarged under the creative (namely intermittent grinding) condition, and the balance between the fatigue preventing operation and the intermittent grinding is achieved.

Compared with the prior art, the utility model provides a safety arrangement and handheld buffing machine for handheld buffing machine, forefinger pressure sensitive element through setting up one side in this scheme and the thumb pressure sensitive element of opposite side is gone up in the handheld position of setting up handheld buffing machine to fix a position handheld posture to the user on handheld position, when not standardizing, thereby can detect the pressure of thumb and forefinger and close the motor through the number of times that the detection is less than the pressure standard, stop polishing, prevent like this to hold not tightly the opportunity of polishing for a long time and lead to the operation in-process unusual the taking off the hand. The total working time is controlled through the accumulated time statistical circuit, so that the phenomenon that the polishing causes human body injury due to negligence caused by long-time fatigue working is prevented. Make the user highly concentrate mental work after a period of time through continuous operation duration statistical circuit, have a rest a period to make the during operation more concentrate on, be difficult for the distraction injury.

It is to be understood that the invention is not limited to the above-described embodiments, and that modifications and variations may be made by those skilled in the art in light of the above teachings, and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.

Claims

1. A safety guard for a hand sander including a main circuit for controlling a motor, the safety guard further comprising:

2. The safety protection device for a hand-held polishing machine according to claim 1, further comprising a pressure operation mode selection switch, wherein the pressure operation mode selection switch comprises a first selection switch arranged on a parallel branch of the holding posture operation relay and a second selection switch arranged on the main circuit, and the first selection switch and the second selection switch are mutually linked switches;

3. The safety shield for a hand sander of claim 2, wherein the malfunction statistic circuit comprises:

4. The safety protection device for a hand sander of claim 3, wherein said main circuit includes a power source, a cumulative time statistic circuit connected to said power source; the cumulative time statistic circuit comprises:

5. The safety protection device for a hand sander of claim 4, wherein a continuous run time statistic circuit is connected to said main circuit between said cumulative time statistic circuit and said motor, said continuous run time statistic circuit comprising a continuous time timer disposed in parallel with said motor, a rest time timer disposed in parallel with said continuous time timer and electrically connected to said continuous time timer, a continuous time timer normally closed contact disposed in series with said motor, and a continuous time timer normally open contact disposed in series with said rest time timer;

6. The safety shield for a hand sander of claim 1 further comprising a brake module disposed in the sanding section of the sander for stopping the motor.

7. The safety shield for a hand sander of claim 6, wherein the brake module comprises a brake switch, a brake assembly electrically connected to the brake switch; the brake switch is used for starting the brake assembly when the misoperation statistical circuit cuts off the power supply of the motor.

8. The safety protection device for a hand sander of claim 7, wherein the brake assembly comprises a film fixedly connected to the output shaft of the motor, and an electromagnetic push rod fixedly disposed on the housing of the hand sander, wherein the electromagnetic push rod is controlled by the brake switch to press or release the film.

9. The safety device for a hand sander as set forth in claim 6, wherein said brake module comprises a turntable fixedly connected to the output shaft of said motor, a brake disc fixedly disposed on the housing of the hand sander, and a resilient tab having one end fixed to the edge of said turntable and the other end abutting against the edge of said brake disc.

10. A hand sander comprising the safety shield of any one of claims 1 to 9 for a hand sander.