Control method and system for adjusting output power of reciprocating saw according to material hardness

Abstract

The present invention relates to a control method and system for adjusting the output power of a reciprocating saw according to the hardness of a material. The method detects the hardness of the material being cut and selects a suitable motor operating voltage to adjust the output power of the motor, thereby avoiding the reciprocating saw from wasting electric energy by using high power to cut low hardness materials, thereby improving the energy utilization rate of the reciprocating saw. For a reciprocating saw powered by a battery pack, the battery life of the battery pack can be effectively extended.

Description

Technical Field

[0001] The present invention relates to a cutting tool, and in particular to a control method and system for adjusting the output power of a reciprocating saw according to the hardness of a material. Background Art

[0002] Reciprocating saws are mainly operated by ordinary users and are mainly used for garden cutting or simple metal cutting. The operation of reciprocating saws is relatively simple. Users only need to press the switch to control the speed of the reciprocating saw motor through the travel of the switch, thereby controlling the cutting speed.

[0003] In the actual cutting process, the reciprocating saw will involve different types of materials, and the hardness of various materials is different. Users usually press the switch to the maximum stroke and use the maximum speed for cutting. However, for materials of different hardness, using the same speed for cutting will result in insufficient power or excess power, resulting in low energy utilization. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a control method for adjusting the output power of a reciprocating saw according to the hardness of the material, so as to solve the technical problem of low energy utilization rate caused by energy waste when the reciprocating saw cuts materials of different hardness.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a control method for adjusting the output power of a reciprocating saw according to the hardness of a material, comprising the following specific steps:

[0006] S1. Drive the motor to rotate with rated output voltage and PWM frequency to make the reciprocating saw work, cut a variety of materials with known hardness, detect the motor working current and obtain the current amplitude width;

[0007] S2. Based on a large amount of hardness and current amplitude width data, the functional relationship between hardness H and current amplitude width I is fitted, that is, I=f(H);

[0008] S3, driving the reciprocating saw to work at the rated output voltage and PWM frequency to cut the material to be cut, detecting the working current amplitude width of the reciprocating saw motor, and calculating the hardness of the material to be cut according to the functional relationship obtained in step S2;

[0009] S4, driving the reciprocating saw with the maximum output power to cut materials with different hardness, and measuring the maximum hardness Hmax of the material that the reciprocating saw can cut under the power;

[0010] S5. Select the material with hardness Hmid and saw it at the highest speed. At the same time, gradually reduce the motor voltage until the reciprocating saw stops sawing. Then gradually increase the motor voltage until the reciprocating saw can saw the material normally. Record the adapted voltage Vmid and hardness Hmid. <Hmax;

[0011] S6. Calculate the slope relationship between hardness and voltage V=f(H) according to the motor voltage value corresponding to the material with maximum hardness Hmax and the motor voltage value corresponding to the hardness Hmid;

[0012] S7, sawing the material of unknown hardness, detecting the amplitude width of the motor working current and calculating the material hardness according to the functional relationship in step S2;

[0013] S8. The controller obtains the adaptation voltage value according to the material hardness obtained in step S7 and the formula V=f(H) in step S6. The controller of the reciprocating saw adjusts the motor working voltage to match the output power of the motor with the material hardness.

[0014] The technical problem further to be solved by the present invention is to provide a control system for adjusting the output power of a reciprocating saw according to the hardness of the material, so as to solve the technical problem of low energy utilization rate caused by energy waste when the reciprocating saw cuts materials of different hardness.

[0015] In order to solve the above technical problems, the technical solution adopted by the present invention is: a control system for adjusting the output power of a reciprocating saw according to the hardness of a material, comprising a power supply, a drive circuit and a motor connected in series, the control end of the drive circuit is electrically connected to a controller and controlled by a PWM signal of the controller, a current detection circuit is connected between the negative pole of the motor and the controller, the controller detects the working current of the motor through the current detection circuit, and the power supply supplies power to the controller at the same time, characterized in that a transformer is connected in series between the power supply and the drive circuit, an on-load tap changer is connected to the output coil of the transformer, the controller is connected to the on-load tap changer, and the number of turns of the output coil connected to the circuit is changed by controlling the on-off of each transistor of the on-load tap changer, thereby adjusting the output voltage of the transformer.

[0016] As a preferred solution, the current detection circuit includes a sampling resistor connected in series to the negative pole of the motor, the other end of the sampling resistor is grounded, and both ends of the sampling resistor are electrically connected to the controller respectively.

[0017] The beneficial effects of the present invention are as follows: the present invention detects the hardness of the material being cut and selects a suitable motor operating voltage, thereby adjusting the output power of the motor, avoiding the reciprocating saw from wasting electricity by using high power to cut low hardness materials, thereby improving the energy utilization rate of the reciprocating saw, and for a reciprocating saw powered by a battery pack, the battery life of the battery pack can be effectively extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0019] Figure 1 It is a working principle diagram of the control system of the present invention;

[0020] Figure 2 It is a circuit connection diagram of the transformer and the on-load tap changer of the present invention;

[0021] Figure 3 It is a specific circuit diagram of the current detection circuit of the present invention. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0023] like Figure 1 and Figure 2 The control system shown in the figure adjusts the output power of a reciprocating saw according to the hardness of the material, including a power supply, a drive circuit and a motor connected in series. The control end of the drive circuit is electrically connected to a controller and is controlled by a PWM signal of the controller. A current detection circuit is connected between the negative pole of the motor and the controller. The controller detects the working current of the motor through the current detection circuit. The power supply supplies power to the controller at the same time. A transformer is connected in series between the power supply and the drive circuit. The output coil L2 of the transformer is connected to a load tap changer. The controller is connected to the load tap changer. The number of turns of the output coil connected to the circuit is changed by controlling the on-off of each transistor of the load tap changer, thereby adjusting the output voltage of the transformer.

[0024] In this embodiment, the on-load tap changer is provided with six transistors, namely Q1 to Q6. The number of turns of the output coil L2 connected to each transistor is different. The controller can connect the output coil L2 with a certain number of turns to the circuit and output a specific voltage by controlling one of the transistors to conduct. Switching different transistors can switch the output voltage of the transformer.

[0025] In actual applications, the controller will switch the transistors in sequence according to the order of the number of coil turns, so that the voltage gradually changes to the target value.

[0026] like Figure 3 As shown, the current detection circuit described in this embodiment includes a sampling resistor R1 connected in series to the negative pole of the motor, the other end of the sampling resistor R1 is grounded, and both ends of the sampling resistor R1 are electrically connected to the controller respectively.

[0027] The control method for adjusting the output power of a reciprocating saw according to the hardness of a material based on the above control system includes the following specific steps:

[0028] S1. Drive the motor to rotate with rated output voltage and PWM frequency to make the reciprocating saw work, cut a variety of materials with known hardness, detect the motor working current and obtain the current amplitude width;

[0029] S2. Based on a large amount of hardness and current amplitude width data, the functional relationship between hardness H and current amplitude width I is fitted, that is, I=f(H);

[0030] S3, driving the reciprocating saw to work at the rated output voltage and PWM frequency to cut the material to be cut, detecting the working current amplitude width of the reciprocating saw motor, and calculating the hardness of the material to be cut according to the functional relationship obtained in step S2;

[0031] S4, driving the reciprocating saw with the maximum output power to cut materials with different hardness, and measuring the maximum hardness Hmax of the material that the reciprocating saw can cut under the power;

[0032] S5. Select the material with hardness Hmid and saw it at the highest speed. At the same time, gradually reduce the motor voltage until the reciprocating saw stops sawing. Then gradually increase the motor voltage until the reciprocating saw can saw the material normally. Record the adapted voltage Vmid and hardness Hmid. <Hmax;

[0033] S6. Calculate the slope relationship between hardness and voltage V=f(H) according to the motor voltage value corresponding to the material with maximum hardness Hmax and the motor voltage value corresponding to the hardness Hmid;

[0034] S7, sawing the material of unknown hardness, detecting the amplitude width of the motor working current and calculating the material hardness according to the functional relationship in step S2;

[0035] S8. The controller obtains the adaptation voltage value according to the material hardness obtained in step S7 and the formula V=f(H) in step S6. The controller of the reciprocating saw adjusts the motor working voltage to match the output power of the motor with the material hardness. In practical applications, the adjustable motor working voltage is divided into multiple gears, and the motor working voltage is adjusted to a gear voltage slightly larger than the adaptation voltage value. For example, the obtained adaptation voltage value is 15.4V, and the adjustable working voltages are ... 12V, 14V, 16V, 18V..., then the motor working voltage is gradually adjusted to 16V.

[0036] Through the above control system and control method, the reciprocating saw can adjust the output power by adjusting the voltage according to the hardness of the material being cut, avoiding energy waste caused by high-power cutting of low-hardness materials and improving energy utilization.

[0037] The above embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A control method for adjusting the output power of a reciprocating saw according to the hardness of a material, characterized in that: The specific steps include: S1. Drive the motor to rotate with rated output voltage and PWM frequency to make the reciprocating saw work, cut a variety of materials with known hardness, detect the motor working current and obtain the current amplitude width; S2. Based on a large amount of hardness and current amplitude width data, the functional relationship between hardness H and current amplitude width I is fitted, that is, I=f(H); S3, driving the reciprocating saw to work at the rated output voltage and PWM frequency to cut the material to be cut, detecting the working current amplitude width of the reciprocating saw motor, and calculating the hardness of the material to be cut according to the functional relationship obtained in step S2; S4, driving the reciprocating saw with the maximum output power to cut materials with different hardness, and measuring the maximum hardness Hmax of the material that the reciprocating saw can cut under the power; S5. Select the material with hardness Hmid and saw it at the highest speed. At the same time, gradually reduce the motor voltage until the reciprocating saw stops sawing. Then gradually increase the motor voltage until the reciprocating saw can saw the material normally. Record the adapted voltage Vmid and hardness Hmid. <Hmax; S6. Calculate the slope relationship between hardness and voltage V=f(H) according to the motor voltage value corresponding to the material with maximum hardness Hmax and the motor voltage value corresponding to the hardness Hmid; S7, sawing the material of unknown hardness, detecting the amplitude width of the motor working current and calculating the material hardness according to the functional relationship in step S2; S8. The controller obtains the adaptation voltage value according to the material hardness obtained in step S7 and the formula V=f(H) in step S6. The controller of the reciprocating saw adjusts the motor working voltage to match the output power of the motor with the material hardness.

2. A control system for adjusting the output power of a reciprocating saw according to the hardness of a material, used to implement the control method of claim 1, characterized in that: It includes a power supply, a drive circuit and a motor connected in series. The control end of the drive circuit is electrically connected to a controller and is controlled by a PWM signal of the controller. A current detection circuit is connected between the negative pole of the motor and the controller. The controller detects the working current of the motor through the current detection circuit. The power supply supplies power to the controller at the same time. It is characterized in that a transformer is connected in series between the power supply and the drive circuit, an on-load tap changer is connected to the output coil of the transformer, and the controller is connected to the on-load tap changer. The number of turns of the output coil connected to the circuit is changed by controlling the on-off of each transistor of the on-load tap changer, thereby adjusting the output voltage of the transformer.

3. The control system for adjusting the output power of a reciprocating saw according to material hardness according to claim 2, characterized in that: The current detection circuit includes a sampling resistor connected in series to the negative pole of the motor, the other end of the sampling resistor is grounded, and both ends of the sampling resistor are electrically connected to the controller respectively.

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