JPS6362362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] This invention relates to a portable electric jigsaw.

[Background technology]

A jigsaw cuts wood by reciprocating the saw blade.
This is an electric tool for cutting metal, etc., but wood and metal have different hardnesses and the cutting methods are also different.

The conventional jigsaw has a main body 4 as shown in Fig. 1.
There is a grip portion 42 for operation approximately above the center of gravity of 1,
An ON/OFF switch 43 is arranged on the grip portion 42. This position is appropriate when cutting a hard material such as metal and the cutting speed is slow, and it is logical that the grip portion 42 is located substantially above the main body 41. However, when cutting relatively soft materials such as wood, the cutting speed is fast and the feeding speed is also fast, so if the grip part 42 is in the conventional position and you push in the feeding direction, the center of gravity will not match the feeding direction. Therefore, a moment is generated with the base 44 as the rotation axis. Therefore,
There are problems such as the main body 41 being twisted and the saw blade 45 breaking, or being unable to cut straight. Further, it is desirable to change the speed of the saw blade 45 depending on the material, but if the rotational speed of the motor is controlled by a switch, there are problems such as the switch operation is cumbersome and the speed switching operation may be made incorrectly.

[Purpose of the invention]

This invention has excellent operability not only when cutting metal etc. at a slow speed, but also when cutting relatively soft materials such as wood at a high speed, and also has an easy switch operation for selecting the motor rotation speed. The purpose is to provide jigsaw.

[Structure of the invention]

The jigsaw of this invention is provided with grip parts at an upper position of the jigsaw body and at a rear position in the direction of movement, and a motor switch is provided on both grip parts, and when the switch at the rear position is turned on, the switch at the upper position is turned on. A motor power supply circuit is provided that increases the rotational speed of the motor.

Embodiment An embodiment of the present invention is shown in FIGS. 2 to 5. In the figure, reference numeral 1 denotes a main body, and a handle 6 is provided, which has a grip portion 6a that can be gripped substantially above the center of gravity G, and a grip portion 6b that can be gripped diagonally above and behind the center of gravity G. Each grip portion 6a, 6b is provided with a switch 5a, 5b. Rear grip part 6b
The center of gravity G of the main body 1 and the portion of the saw blade 27 facing the material to be cut can be connected by a substantially straight line. The main body 1 is composed of a main housing 4 that holds the motor part, the handle 6, covers 2 and 3 that house the transmission part, etc., and a base 7 that abuts against the workpiece. A cord 8 connected to an AC commercial power source serving as a power source is led out from the rear surface of the main body 1. The inside of the main body 1 is constructed as follows. A gear 11 formed at the tip of an output shaft 10' of the motor 10 meshes with a gear 12. The gear 12 is a fixed support shaft 13
The gear 12 is supported by an eccentric cam 14 that is eccentric from the center of rotation. The eccentric cam 14 has a balance weight 15 having a horizontal elongated hole 15a.
are engaged and arranged. The balance weight 15 is provided with a long hole 15b in which a guide pin 16 fixedly protruding from the cover 2 is engaged so that the rotation of the gear 12 is restricted to only reciprocating motion without rotation. A weight holder 1 is attached to the gear 12 in contact with the side surface of the eccentric cam 14.
8 with screws, balance weight 15 to gear 1
It should be kept between 2 and 2. A pin 17 is provided on the weight holder 18 eccentrically with respect to the fixed support shaft 13. The eccentric direction of the pin 17 is the eccentric direction of the eccentric cam 14.
in the opposite direction to the eccentric direction. A roller 20 is rotatably fitted onto the pin 17, and a groove-shaped connector 21 is attached to the pin 17.
The connector 21 is disposed so that the roller 20 is rotatably engaged with the inner wall of the connector. Connector 21 is fixed to plunger 22. The plunger 22 is
The bearings 23 and 24 restrict movement only up and down. A saw blade holder 26 is disposed at the lower end of the plunger 22, and the saw blade holder 26 allows the saw blade 27 to
Install.

The power supply circuit for the motor 10 is connected to the rear switch 5b.
When the upper switch 5a is operated, the rotational speed of the motor 10 becomes faster than when the upper switch 5a is operated, and the circuit configuration is, for example, as shown in FIG. In the figure, 30 is a diode,
31 is a field winding, and 32 is a power source. switch 5
b has two interlocking contacts a and b.

Operation The rotation of the motor output shaft 10' is transmitted from the gear 11 to the gear 12, and further rotates the weight holder 18 connected to the gear 12. Weight holder 1
The pin 17 protruding from and fixed to 8 similarly rotates while ensuring an eccentric position. The pin 17 is engaged with the connector 21 via the roller 20, and since the roller 20 on the pin 17 rolls on the inner wall of the connector 21, the rotational movement of the pin 17 is caused by the reciprocating movement of the connector 21, that is, the plunger 22. While being converted into a reciprocating motion, the eccentric shaft 14, which is eccentric from the central axis of the gear 12 to a position facing the pin 17 of the weight holder 18, also rotates in the same way as the gear 12. The balance weight 15 engaged with the outer periphery of the eccentric shaft 14 can only move vertically without rotating due to the elongated hole 15a of the engaging portion and the guide pin 16a. balance weight 1
5 moves in the opposite direction to move in opposition to the plunger 22. That is, the balance weight 15 moves to the bottom dead center position relative to the top dead center of the plunger 22. Therefore, balance weight 15
moves to eliminate the imbalance of the main body 1 and balance the main body 1.

Next, the operations of the handle 6 and switches 5a, 5b will be explained. When the cutting feed speed is slow, such as when cutting a hard material such as metal or a relatively soft material such as wood, the grip portion 6a is located approximately above the center of gravity G of the main body 1 as shown in FIG. , and operate the switch 5a. In this case, the operability is good like the conventional one, and cutting can be performed along the cutting line.

When cutting a relatively soft material such as wood in a straight line by increasing the cutting feed speed, grasp the grip 6b behind the center of gravity G in the feeding direction as shown in Fig. 4, and operate the switch 5b. let me body 1
push forward. At this time, the direction of the pushing force matches the cutting direction of the saw blade 27, and the center of gravity G of the main body 1 is located in the direction of the pushing force. Therefore, it has good operability and can cut straight at a high cutting speed. In addition, in this case, since the switch 5b is pressed, the motor 10 rotates faster and the saw blade 27
The reciprocating speed becomes faster. When cutting soft materials such as wood, increasing the reciprocating speed of the saw blade 27 will result in a more beautiful cut surface. The operation of the power supply circuit by operating the switches 5a and 5b is as follows. That is, when the switch 5a is operated, only a current half-wave rectified by the diode 30 flows, so that the rotational speed of the motor 10 is slower than that of the switch 5b, which operates to short-circuit the diode 30.

〔Effect of the invention〕

In the jigsaw of the present invention, the jigsaw main body is provided with grip portions at an upper position and a rear position in the direction of movement, motor switches are provided on both grip portions, and when the switch at the rear position is turned on, the switch at the upper position is turned on. Since it is equipped with a motor power supply circuit that increases the rotational speed of the motor, it has good operability for quickly cutting relatively soft materials such as wood, and also has good operability for cutting hard materials such as metal. I can do it. Moreover, when cutting in a straight line at a high cutting feed speed, it is easier to operate by holding the grip at the rear, and when cutting in a curve at a slow cutting feed speed, it is easier to operate by holding the grip at the top. When you use your hand to turn on a nearby switch, the motor rotates at the appropriate speed. Therefore, there is no need for a speed switching operation, and the switch operation is simple.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional example, Fig. 2 is a cutaway side view of an embodiment of the present invention, Fig. 3 is a perspective view showing its metal material cutting operation, and Fig. 4 similarly shows its wood cutting operation. The perspective view and FIG. 5 are also electrical circuit diagrams. 1...Main body, 5a, 5b...Switch, 6...
Handle, 6a, 6b...Grip portion, 7...Base, 10...Motor, 27...Saw blade.

Claims (1)

[Claims] 1. A jigsaw main body is provided with grips at an upper position and a rear position in the direction of movement, and motor switches are provided on both grips, and when the switch at the rear position is turned on, the motor speed is lower than when the switch at the upper position is turned on. A jigsaw equipped with a motor power circuit that increases rotation speed.