JP3716591B2 - Hammer drill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hammer drill for drilling a work material such as concrete.
[0002]
[Prior art]
There is a hammer drill that makes it easy to drill a work material such as concrete by giving an axial blow to the drill bit at the same time as rotating.
An example is shown in FIG. A pinion 10 fixed to the output shaft of the motor 1 is engaged with an intermediate gear 12 provided at one end of the intermediate shaft 11, and a gear portion 13 provided at the other end of the intermediate shaft 11 is freely rotatable around the axis 14. A chuck portion 18 is provided on a spindle 17 that is engaged with an output gear 15 fixed by a key 19 and is connected to a cylinder 14 by a pin 16, and the bit 6 is held by the chuck portion 18. Bit 6 is transmitted.
[0003]
Further, the reciprocating bearing 2 is mounted on the outer periphery of the intermediate shaft 11 through a bearing 28, and a clutch plate 25 splined to the spline portion provided on the intermediate shaft 11 is provided with a meshing portion with the reciprocating bearing 2, A piston 4 provided at one end with a universal joint 3 through which a rod 20 protruded from an outer race of the reciprocating bearing 2 is inserted is slidably disposed in the cylinder 14, and an O-ring 41 is provided in the piston 4 on the outer peripheral surface. If the hammer 40 provided in the slidable housing is slidably housed and meshed with the clutch plate 25 and the reciprocating bearing 2 by urging by the spring 26, the rotation of the intermediate shaft 11 is transmitted to the reciprocating bearing 2 via the clutch plate 25. However, at this time, the rod 20 to which the movement direction is restricted by the piston 4 oscillates. The piston 4 receiving this performs reciprocating linear motion. At this time, the hammer 40 disposed inside the piston 4 is driven to reciprocate via an air spring, and at the time of advance, an impact impact in the axial direction is applied to the bit 6 via the striker 5 disposed inside the spindle 17. Add. In the drawing, reference numeral 27 denotes a switching member for moving the clutch plate 25 against the spring 26 to separate the reciprocating bearing 2 and the intermediate shaft 11 and to set the operation mode in which only the bit 2 is rotated.
[0004]
[Problems to be solved by the invention]
In such a hammer drill, the sliding portion between the rod 20 in the reciprocating bearing 2 and the universal joint 3 through which the rod 20 is inserted is supported by the piston 4 so as to be rotatable around the axis. Since a large load is applied and the posture is changed drastically as the rod 20 swings, the lubricant is scattered immediately if the lubricant is simply applied to the sliding portion. There is a fear. Of course, by using an oil-impregnated bearing or the like for the sliding portion, the risk of seizure can be greatly reduced, but in this case, a problem arises in terms of cost.
[0005]
The present invention has been made in view of these points, and an object of the present invention is to provide a hammer drill that can prevent seizure at low cost.
[0006]
[Means for Solving the Problems]
Therefore, the present invention relates to a hammer drill in which a swing-driven rod is inserted into a universal joint provided on a piston that is supported so as to be slidable, and the piston reciprocates. Rutotomoni provided a flow path for guiding the floating lubricant parts, by providing a recess comprising a lubricant reservoir and to the flow path, the cross-sectional of the universal joint outer side than the cross-sectional area of the sliding portion in the flow path It is characterized by a large area . Since the scattered or vaporized lubricant adheres to the sliding part through the flow path provided with the recess, the amount of floating lubricant guided to the sliding part can be increased without reducing the strength of the universal joint. It can be done and will not cause seizure.
[0007]
The flow path here is provided on the inner surface of the insertion hole through which the rod of the universal joint is inserted, even if it is provided as a hole connecting the inner surface of the insertion hole through which the rod of the universal joint is inserted and the outer surface of the universal joint. The both ends may be provided as grooves that open to the outer surface of the universal joint.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An example of the embodiment of the present invention will be described. Since the form as a hammer drill is the same as that shown in FIG. 5, the description is omitted, but the rod 20 protruding from the reciprocating bearing 2 is inserted. As shown in FIG. 1, the universal joint 3 provided with the insertion hole 30 is provided with a hole having one end connected to the insertion hole 30 and the other end opened to the axial end surface of the universal joint 3 as a lubricant channel 35. is there. In the figure, reference numeral 31 denotes chamfered portions provided at both ends of the insertion hole 30.
[0009]
When such a universal joint 3 is mounted on the piston 4 and the rod 20 is inserted into the insertion hole 30 and the rod 20 is swung by rotating the reciprocating bearing 2, the rod 20 slides in the insertion hole 30. The piston 4 is caused to reciprocate linearly through the universal joint 3 while moving. At this time, the lubricant is scattered in the gear box containing the drive mechanism of the hammer drill, and the heat is generated by the drive mechanism. The lubricant thus applied reaches the sliding portion between the rod 20 and the universal joint 3 through the lubricant channel 35 and adheres to the surface of the rod 20. For this reason, seizure does not occur in the sliding portion.
[0010]
The other end of the lubricant channel 35 whose one end is connected to the insertion hole 30 may be opened on the outer peripheral surface as shown in FIG. 2 instead of the end surface of the universal joint 3.
In addition, as shown in FIG. 3, the lubricant flow path 35 preferably has a larger cross-sectional area on the other end side than the one end side connected to the insertion hole 30. Since the amount of lubricant that adheres to the rod 20 through the lubricant channel 35 is larger than that in which the cross-sectional area of the lubricant channel 35 is constant over the entire length, seizure can be more reliably prevented. In particular, when the cross-sectional area on the other end side is increased by providing the recess 36 that functions as a lubricant reservoir as in the illustrated example, lubrication can be performed more effectively. In addition, although it is preferable in terms of lubrication that the cross-sectional area on one end side of the lubricant channel 35 is also increased, in this case, it is required for the universal joint 3 that receives the oscillating rod 20 and performs linear reciprocation. In addition to making it difficult to ensure the strength, the contact area between the rod 20 and the universal joint 3 is reduced, and the surface pressure is increased, which may cause seizure.
[0011]
The lubricant channel 35 may be provided as a groove provided on the inner surface of the insertion hole 30 as shown in FIG. The lubricant flow path 35 formed as a groove opened at both ends of the insertion hole 30 allows the lubricant that is scattered or vaporized when the oscillating rod 20 slides in the insertion hole 30. Since it is rolled up and taken into the lubricant channel 35, seizure between the universal joint 3 and the rod 20 can be prevented also in this case.
[0012]
In addition, although what provided the lubricant flow path 35 in the universal joint 3 side was shown, you may provide in the rod 20 side.
[0013]
【The invention's effect】
As described above, in the present invention, in a hammer drill in which a swing-driven rod is inserted into a universal joint provided on a piston that is slidably supported, and the piston reciprocates, the universal joint, the rod, Since the flow path for guiding the floating lubricant is provided in the sliding portion, the floating lubricant that has been scattered or vaporized can be attached to the sliding portion through the flow path. It is possible to prevent seizure at a lower cost than when using an oil-impregnated bearing without causing seizure with the rod.
[0014]
In the present invention, by providing a recess as a lubricant reservoir in the flow path, the cross-sectional area on the outer surface of the universal joint is made larger than the cross-sectional area on the sliding portion side in the flow path , and the flow is scattered. Since the vaporized lubricant adheres to the sliding part through the flow path provided with the recess, the amount of the floating lubricant guided to the sliding part is increased without reducing the strength of the universal joint. It is possible to prevent burn-in more reliably.
[Brief description of the drawings]
FIG. 1 shows an example of an embodiment of the present invention, where (a) is a sectional view of a universal joint, (b) is a plan view of the universal joint, and (c) is a sectional view of the universal joint and a rod. .
FIG. 2 shows another example of the above, in which (a) is a cross-sectional view of a universal joint, (b) is a plan view of the universal joint, and (c) is a cross-sectional view of the universal joint and a rod.
FIG. 3 shows still another example of the above, in which (a) is a sectional view of the universal joint, (b) is a plan view of the universal joint, and (c) is a sectional view of the universal joint and the rod.
4A and 4B show another example of the above, wherein FIG. 4A is a cross-sectional view of a universal joint, FIG. 4B is a plan view of the universal joint, and FIG. 4C is a cross-sectional view of the universal joint and a rod.
FIG. 5 is a partial cross-sectional view of a hammer drill.
[Explanation of symbols]
3 Universal joint 20 Rod 30 Insertion hole 35 Lubricant flow path
36 recess

Claims (3)

In a hammer drill in which a swinging rod is inserted into a universal joint provided on a piston that is slidably supported to cause the piston to reciprocate, floating lubricant is applied to the sliding portion between the universal joint and the rod. Rutotomoni provided a flow path for guiding, by providing the recess as a lubricant reservoir in the flow path, that is a large cross-sectional area of the universal joint outer side than the cross-sectional area of the sliding portion in the flow path Hammer drill characterized by   The hammer drill according to claim 1, wherein a hole connecting the inner surface of the insertion hole through which the rod of the universal joint is inserted and the outer surface of the universal joint is provided as a flow path.   2. The hammer drill according to claim 1, wherein a groove is provided in an inner surface of an insertion hole into which a rod in the universal joint is inserted and both ends open to the outer surface of the universal joint.

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