JP3657802B2 - Housing connection structure for power tools - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connecting structure for connecting a barrel and a cylindrical housing such as a tool holder in an electric tool such as an electric hammer or a hammer drill.
[0002]
[Prior art]
FIG. 6 is a cross-sectional explanatory view of the tip portion of the electric hammer 1, and a cylindrical tool holder 6 into which a bit 18 is inserted is coaxially connected to a cylindrical barrel 4 incorporating a striking mechanism. The barrel 4 and the tool holder 6 are connected to the female screw portion 13 formed on the inner periphery of the barrel 4 and the male screw portion 15 formed on the outer periphery of the tool holder 6 as a butt end portion of the barrel 4. The front end 14 is screwed in until it comes into contact with the seat 16 that is the butted end of the tool holder 6, and is tightened with a constant torque. Reference numeral 21 denotes an O-ring that seals between the tip portion 14 and the seat portion 16.
[0003]
[Problems to be solved by the invention]
On the other hand, the insertion portion 19 of the bit 18 in the tool holder 6 has a regular hexagonal cross section and is fitted to the insertion hole 7 of the same shape on the tool holder 6 side. If the angle in the rotational direction is not properly adjusted with respect to the barrel 4, the angle at the end of tightening will shift as shown in FIG. Therefore, not only the bit 18 but also the direction of the tool retainer 11 mounted integrally with the tool holder 6 is shifted in the rotation direction, and the usability is deteriorated when the bit 18 has a directionality such as a chisel. Therefore, conventionally, the tool holder 6 is positioned with respect to the barrel 4 by setting the cutting start position of the female screw portion 13 and the male screw portion 15 so that the tool holder 6 has an appropriate angle at the end of tightening. However, since the accuracy of threading is required and an error may occur, the possibility that the positioning may be inappropriate after all cannot be completely eliminated.
[0004]
Therefore, the invention described in claim 1 has a simple configuration, and the barrel and the tool holder can always be connected at an appropriate angle in the rotational direction regardless of the threading accuracy, so that the usability is not impaired and the manufacturing process is simplified. An object of the present invention is to provide a housing connection structure in an electric tool that can be realized.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is made of brass or aluminum , which is softer than the barrel and the tool holder between the two butted ends and is plastically deformed by pressing the both butted ends when tightened . An intermediate is arranged.
In addition to the object of the first aspect, the invention described in claim 2 applies the intermediate body over the entire circumference of both butted ends in order to rationalize the configuration by using the intermediate body also as a sealing member. It is a ring body that can be contacted.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The electric hammer 1 shown in FIG. 1 has the same basic configuration as the conventional one described in FIG. Reference numeral 2 denotes a motor housing having a built-in motor. A crank housing 3 having a built-in crank mechanism for converting the rotation of the motor into a reciprocating motion of the piston is connected in an L shape. A barrel 4 as one cylindrical housing for holding a cylinder with a built-in striking mechanism is fixed to the front of the crank housing 3 by bolts 5, 5. The tool holder 6 as the other cylindrical housing into which the bit 18 is inserted is connected coaxially. Reference numeral 8 denotes a handle provided continuously behind the motor housing 2, 9 denotes a grip attached to the barrel 4, and 10 denotes a barrel cover mounted on the barrel 4. Further, as shown in FIGS. 2 and 3, the insertion hole 7 of the bit 18 formed in the tool holder 6 has the same regular hexagonal cross section as the insertion part 19 of the bit 18, and is inserted into the tool holder 6. Although the worn bit 18 is restricted in rotation and can only move back and forth, a tool retainer 11 having a notch 12 through which the circular portion 20 of the bit 18 passes is attached to the tool holder 6. Is restricted from popping out.
[0007]
The connection between the barrel 4 and the tool holder 6 is made by screwing a female screw portion 13 formed on the inner periphery of the front end of the barrel 4 and a male screw portion 15 formed on the outer periphery of the rear end of the tool holder 6. The front end of the barrel 4 and the front of the male screw part 15 in the tool holder 6 are respectively provided with a tip part 14 and a seat part 16 as a butt end part, and the male screw part 15 is connected to the female screw part 13. When screwed, the tip portion 14 and the seat portion 16 can come into contact with each other. Reference numeral 17 denotes a brass ring interposed between the front end portion 14 and the seat portion 16. Since the barrel 4 and the tool holder 6 are made of steel, the ring 17 sandwiched between the two is softer. .
[0008]
In the electric hammer 1 configured as described above, when the barrel 4 and the tool holder 6 are connected, the male screw portion 15 of the tool holder 6 is provided with the ring 17 and the male screw portion 15 is attached to the barrel 4 in this state. Screwed into the female screw portion 13. Then, since the tip end portion 14 of the barrel 4 and the seat portion 16 of the tool holder 6 stop with the ring 17 interposed therebetween, if the bolts are tightened to a predetermined tightening torque as they are, they are pressed between the barrel 4 and the tool holder 6. The ring 17 is plastically deformed. If the rotational angle of the insertion hole 7 of the tool holder 6 is shifted as shown in FIG. 4 when the tightening torque is reached, if the tightening is continued as it is, the tool is deformed by the plastic deformation of the ring 17. In order to allow further rotation of the holder 6, the tool holder 6 can be screwed in until a proper pair of sides of the regular hexagonal insertion hole 7 are vertically positioned as shown in FIGS. Become.
[0009]
Incidentally, FIG. 5 is a graph showing an angle at which the tool holder 6 is allowed to rotate with respect to the tightening torque. When the graph a is the thickness of the ring 17, the graph b is the thickness 5 of the ring 17. 0.0 mm and the case where the graph c does not use the ring 17 respectively. When the tightening torque is in the range of 2200 kgfcm to 2800 kgfcm, in graph c without the ring 17, the allowable angle is only about 6 to 7 °, and even if the tightening torque is increased, it remains as small as about 10 °. However, in the graphs a and b provided with the ring 17, it can be corrected up to about 20 ° even with the same tightening torque, and it can be seen that this correctable angle increases as the tightening torque increases ( If the tightening torque exceeds 4000kgfcm, it will be 40 ° or more).
[0010]
Thus, the electric hammer 1 has a simple configuration in which the soft ring 17 is interposed between the barrel 4 and the tool holder 6, and even if the angle of the insertion hole 7 of the tool holder 6 is shifted in the rotational direction. By allowing the rotation accompanying the plastic deformation of the ring 17, the insertion hole 7 of the tool holder 6 can be positioned so as to have an appropriate angle. Therefore, it is not necessary to set the threading of the female screw portion 13 and the male screw portion 15 in consideration of the angle of the insertion hole 7 at the end of tightening, and the manufacturing process is simplified. Further, the positioning of the insertion hole 7 makes it possible to always insert the bit 18 at an appropriate angle, so that the usability of the electric hammer 1 is not impaired.
Further, here, since the plastically deforming ring 17 is in close contact with the entire circumference of the tip portion 14 and the seat portion 16 facing each other, a sealing property between the barrel 4 and the tool holder 6 can be secured, as shown in FIG. The seal member such as the O-ring 21 is omitted and the ring 17 can be used as a rational configuration.
[0011]
The intermediate body is not limited to the ring body such as the ring 17, but may be a C-shape or a discontinuous body with overlapping ends, and only one intermediate body such as the ring 17 is disposed. Alternatively, a plurality of sheets can be stacked and connected. In addition to brass, the material can be made of aluminum or the like as long as it is softer than the cylindrical housings positioned at the front and back and plastically deforms when tightened.
And in the said form, although the barrel 4 becomes a female screw and the tool holder 6 becomes a male screw, it does not interfere with this, The position which provides an intermediate body is contrary to the said form which carries out exterior to the male screw side, It can also be arranged between butted ends formed by a step provided on the inner periphery on the female screw side and a male screw tip.
[0012]
【The invention's effect】
According to the first aspect of the present invention, the barrel and the tool holder rotate with the plastic deformation of the intermediate body with a simple configuration in which the intermediate body made of brass or aluminum is interposed between the barrel and the tool holder. Positioning can be performed so as to have an appropriate angle in the direction. Therefore, it is not necessary to set the threading of the female screw portion and the male screw portion in consideration of the final angle, and the manufacturing process is simplified. Further, since the barrel and the tool holder can always be connected at an appropriate angle, the usability is not impaired by the angle of the inserted bit.
According to the second aspect of the invention, in addition to the effect of the first aspect, the intermediate body is a ring body that can abut over the entire circumference of the abutting end portion. Since it closely adheres to the entire circumference of the butting ends facing each other, the sealing property between the barrel and the tool holder can be secured, and the ring body can be a rational configuration that can also be used as a sealing member such as an O-ring.
[Brief description of the drawings]
FIG. 1 is an overall view of an electric hammer.
FIG. 2 is a cross-sectional explanatory view of a tip portion of an electric hammer.
FIG. 3 is an explanatory view of the electric hammer as viewed from the front.
FIG. 4 is an explanatory diagram of an electric hammer with an inappropriate tool holder angle as viewed from the front.
FIG. 5 is a graph showing a relationship between a tightening torque and a correctable angle.
FIG. 6 is a cross-sectional explanatory view of a tip portion of a conventional electric hammer.
[Explanation of symbols]
1 .... Electric hammer, 4 .... Barrel, 6 .... Tool holder, 7 .... Insert hole, 11 .... Tool retainer, 13 .... Female thread part, 14 .... Tip part, 15 .... Male thread part, 16 ··· Seat, 17 · · Ring, 18 · · Bit.

Claims (2)

A cylindrical tool holder into which a bit is inserted is coaxially screwed into a cylindrical barrel, and abutting ends formed so as to face each other are brought into contact with each other and tightened with a predetermined torque. A housing connection structure in a power tool,
In the electric tool characterized in that an intermediate body made of brass or aluminum that is softer than the barrel and the tool holder and is plastically deformed by pressing of the both butting ends during the tightening is disposed between the both butting ends. Housing connection structure. The connection structure of the housing in the electric tool according to claim 1, wherein the intermediate body is a ring body capable of contacting the entire circumference of both butted ends.

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