JPS6259794A - Hammer drill - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hammer drill that performs drilling work in rocks, etc. while applying an impact to the tip of the drill tip using a pressure fluid such as compressed air.

(Background of the invention) A bit shank is attached to the tip side of an outer cylinder filled with bubbles to a support that supplies pressurized fluid such as compressed air, so that it can move forward and backward, and the bit shank is struck by a piston that reciprocates within the outer cylinder. Hammer drills have been known in the past (for example, Japanese Patent Publication No. 59-50837). In this case, pressure fluid is supplied to two pressure chambers defined by a piston at a predetermined timing, and pressure fluid is supplied at a predetermined timing. It is connected to the exhaust passage.

Conventional hammer drills of this type have a back head and
The distributor and the inner cylinder were formed separately, and the pressure fluid supplied from the support was configured to be guided by the distributor to the supply path formed between the inner and outer cylinders.

FIG. 5 is a sectional view of the vicinity of a distributor in a conventional device, and in this figure, reference numeral 100 is a back head, 102 is an outer cylinder, and 10
Reference numeral 4 designates an inner cylinder mounted within this outer cylinder 102, and 106 also represents a distributor. A check valve 108 is provided between the distributor 106 and the back rad 100, and the pressure fluid supplied from the support (not shown) is passed through the check valve 108.
, a supply path 110 formed in the axial direction of the distributor 106, a bow formed in the inner cylinder 104) 112°, and a supply path 110 formed in the inner cylinder 104 and the outer cylinder 102 through the supply path 114 formed between the inner cylinder 104 and the outer cylinder 102.
02. Further, a rod-shaped guide 116 is integrally provided on the distributor 106 and protrudes, and the guide 116 enters and exits the exhaust passage 120 as the piston 118 moves. The guide 116 and the piston 118 form an exhaust valve 122.

As described above, in the conventional device, the guide 116 constituting the exhaust valve 122 is formed integrally with the distributor 106, so it is necessary to separate the inner cylinder 104 from the distributor 106 for machining reasons, and the check valve Due to the provision of the distributor 108, the distributor 106 and the back head 100 had to be formed separately.

This has resulted in the disadvantage that the number of parts has increased and ease of assembly has been poor.

Furthermore, since the distributor 106 is formed with an axial supply path 110, the outer diameter of the distributor 106 becomes large, and the outer cylinder 102
It was difficult to reduce the outer diameter of the For this reason, there was a problem in that it was impossible to drill holes with small diameters.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and it aims to reduce the number of parts and improve assembly efficiency, and to reduce the outer diameter of the outer cylinder to enable drilling of small diameter holes. The purpose is to provide hammer drills.

(Structure of the Invention) According to the present invention, the purpose is to provide a back head connected to a support for supplying pressure liquid, an outer cylinder fixed to the back head, and a back head that can freely move forward and backward toward the tip side of the outer cylinder. A first pressure chamber is provided between the bit shank and the bit shank, and an inner cylinder that forms the pressure fluid supply path between the inner surface of the outer cylinder and the bit shank. a piston that forms two pressure chambers, respectively; an exhaust passage formed on the center axis of the piston and the bit shank, and an exhaust passage that is opened and closed by the movement of the bit shank and the piston and connects the first and second pressure chambers to the exhaust gas. In the hammer drill, the back head and the inner cylinder are integrally formed, and the back head and the inner cylinder are integrally formed, and the back head and the inner cylinder are integrally formed. This is accomplished by using a hammer drill, which is characterized by having a guide fixed thereto which penetrates in the axial direction and forms the second exhaust valve with its tip facing the exhaust passage of the piston.

(Flow side) Fig. 1 is a sectional view of one embodiment of the present invention, and Fig. 2 is a cross-sectional view of the first embodiment of the present invention.
An exploded view of the vicinity of the exhaust valve, Figures 3 and 4 are ■ in Figure 1.
They are a sectional view taken along the -m line and a sectional view taken along the ff-IV line.

In FIG. 1, reference numeral 10 is a back head. This backhead IO is fixed to a support (not shown) that supplies pressure fluid. 12 is an outer cylinder screwed onto the back head 10, and 14 is a drill chuck screwed onto the tip of the outer cylinder 12. This drill chuck 14 and outer cylinder 12
The bit shank 18 is held on the inner surface of the ring 16.
is held so as to be able to reciprocate, and a bitpode 22 having a tip 20 implanted therein is fixed to its tip.

The back head 10 has a valve chamber 2 that opens toward the support body.
4 and an inner cylinder 26 extending into the outer cylinder 12 are integrally formed, and a guide 28 is inserted into the inner cylinder 26 from the valve chamber 24 side. This guide 28 can be made of polyacetal resin such as Delrin (trade name of DuPont). 30
is a check valve loaded in the valve chamber 24, and the guide 2
A valve body 32 is slidably attached to the tip of the valve body 8, a valve seat 36 that an O-ring 34 provided on this valve body 32 comes into contact with, and a spring 38 that presses the valve body 32 toward this valve seat 36. Be prepared. The valve seat 36 is held within the valve chamber 24 by a support that is screwed into the back 10.

40 is a piston, one end of which faces the shank 18, and a first pressure chamber 42 is formed in a portion surrounded by these and the outer cylinder 12. The other end of the piston 40 is in sliding contact with the inner surface of the inner cylinder 26 to form a second pressure chamber 44 within the inner cylinder 26 . Four grooves 26a are formed in the axial direction on the outer peripheral surface of the inner cylinder 26, and these grooves 26a and the outer cylinder 12
A pressure fluid supply path 46 is formed between the two. One end of this supply path 46 communicates with the valve chamber 24 via a supply path 48 diagonally bored in the radial direction in the back hole IO, and the other end communicates with the outer cylinder 12 and the piston. It communicates with the first pressure chamber 42 via a supply path 50 formed between the first pressure chamber 40 and the first pressure chamber 40 . 52
is the exhaust passage formed along the center axis of the bit shank,
54 is an exhaust passage formed on the central axis of the piston 40. A blow tube 56 is attached to the bit shank 18 and can be inserted into and removed from the exhaust passage 54 of the piston 40.
The relative movement between the blow tube 56 and the piston 40 opens and closes the first exhaust valve 58, which connects and connects the first pressure chamber 42 and the exhaust passages 52, 54.

As shown in FIG. 2, the exhaust passage 5 of the bit shank 18
The annular groove 60 formed on the inner surface of the exhaust passage 5 has an inner diameter.
A set ring 62 as a locking member having a returning behavior is engaged so that the inner diameter of the exhaust passage 52 is slightly smaller than the inner diameter of the exhaust passage 52, and a coil spring 66 is locked to a stepped portion 64 on the inner surface of the exhaust passage 52. On the other hand, an annular groove 68 is formed in the blow tube 56, and the blow tube 56 is set by inserting the blow tube 56 into the exhaust passage 52, pressing the slope 56a of the end surface against the slope 62a of the set ring 62, and pushing the set ring 62 open. Ring 62 engages an annular groove 68 in blow tube 56 . At this time, the blow tube 56 is compressing the coil spring 66.

As a result, the blow tube 56 is always urged toward the piston 40, and the set ring 62 locks the blow tube 56 to the bit shank 18 against the urging force of the spring 66. Note that the outer diameter of the blow tube 56 is slightly smaller than the inner diameter of the exhaust passage 52, and the blow tube 56 is slightly movable in the radial direction. Further, 70 is an O-ring that maintains airtightness between the blow tube 56 and the exhaust passage 52.

A second exhaust valve 72 is formed by the guide 28 and the exhaust passage 54 of the piston 40 into which the tip of the guide 28 enters and exits. Note that the piston 40 and the inner cylinder 26 are formed with stepped portions 40a and 26b, respectively, and the screw l-
When 740 moves a predetermined amount toward the second pressure chamber 44, both step portions 40a and 26b overlap, and the pressure fluid supply path 46 becomes the second pressure chamber 44.
It communicates with the pressure chamber 44 of.

74 is a boat bored in the inner cylinder 26, and when the piston 40 moves to the right from the state shown in FIG.
is communicated with the pressure chamber 44.

Next, the operation of this embodiment will be explained. Now, when this hammer drill is inserted into a hole in a rock and its tip is raised above the bottom of the hole, that is, with the bit shank 18 free, the pressure fluid supplied from the support opens the check valve 30 and Through the passage 48.46.50 the first pressure chamber 42
guided by. If the hole in the rock is downward, the piston 4
0 follows the bit shank 18 and the piston 40 opens the boat 74 so that pressure fluid is directed from the bit pod 22 through the boat 74, the second pressure chamber 44, the exhaust passage 54.degree. 52 and to the bottom of the hole. Therefore, the crushed powder inside the hole is discharged together with the pressure fluid to the outside through a gap between the outer cylinder 12 and the hole.

If the hole in the rock faces upward, the bit shank 18 will be pushed upward by the pressure in the first pressure chamber 42, while the piston 40 will move toward the second pressure chamber 44, and the first exhaust valve 58 will open. open. Therefore, the pressure fluid is discharged from the first pressure chamber 42 from the tip of the bit holder 22 through the blow tube 56 and the exhaust passage 52.

When the hammer drill is pressed into the hole in the rock, the bit shank 18 is forced into the barrel 12, the blow tube 56 enters the exhaust passage 54, and the first exhaust valve 58 is closed. Therefore, the internal pressure of the first pressure chamber 42 increases, and the piston 40 is pushed toward the second pressure chamber 44. piston 4
When the guide 28 enters the exhaust passage 54 of the piston 44 and the second exhaust valve 72 closes, the second pressure chamber 44
It is pressurized by And the piston 40 and the inner cylinder 26
When the step portions 40a and 26b overlap, pressure fluid flows from the first pressure chamber 42 to the second pressure chamber 44. At this time, the tube 56 escapes from the piston 40 and the second exhaust valve 58
is opened, and the pressure fluid is discharged from the first pressure chamber 42 to the exhaust passage 52.
is discharged. Therefore, the pressure in the first pressure chamber 42 suddenly decreases, and the pressure fluid in the second pressure chamber 44 expands, causing the piston 4
0 rapidly moves to the bit shank 18 side and hits the bit shank 18. This impact causes the tip 20 to crush the rock. The crushed powder is discharged from between the inner wall of the hole and the outer wall of the outer cylinder 12 together with the discharged pressure fluid.

When assembling this hammer drill, after assembling the blow tube 56 to the bit shank 18 in advance, the drill chuck 14 and the ring 16 are attached to the bit shank 18.
, insert the drill chuck 14 from the tip side of the outer cylinder 12, and tighten it.

Note that the ring 16 has a cut at one place and is enlarged in diameter and attached to the bit shank 18. Guide 2 for back head 10
8, one end of the piston 40 is inserted into the inner cylinder 26, the piston 40 and the inner cylinder 26 are inserted from the other end side of the outer cylinder 12, and the back head 10 is tightened to the outer cylinder 12. Finally, the check valve 30 is assembled and the valve seat 36 is pressed down with a support to complete the assembly.

(Effects of the Invention) As described above, the present invention integrates the members corresponding to the distributor and the inner cylinder in the conventional device with the back head, thereby reducing the number of parts and improving ease of assembly. Further, since a distributor is not required, it is possible to reduce the diameters of the inner cylinder and the outer cylinder, and it is possible to obtain a drill head suitable for drilling small-diameter holes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a cross-sectional view of the first embodiment.
An exploded view of the vicinity of the exhaust valve, Figures 3 and 4 are m in Figure 1.
Figure 5 is a sectional view of the first exhaust valve in the conventional device. 12... Outer cylinder, 18... Bit shank, 26...
-Inner cylinder, 40...piston, 42...wSl pressure chamber. 44...Second pressure chamber, 46.48...Supply passage, 52.54...Exhaust passage, 58...First exhaust valve, 72...Second exhaust valve. Procedure Neyama Seisho (self-motivated) October 98, 1985

Claims (1)

[Claims] A back head connected to a support that supplies pressure liquid, an outer cylinder fixed to the back head, a bit shank attached to the tip side of the outer cylinder so as to be movable forward and backward; A first pressure chamber is formed between the bit shank and an inner cylinder that forms the pressure fluid supply path between the inner surface of the outer cylinder and a second pressure chamber is formed within the inner cylinder. a piston, an exhaust passage formed on the central axes of the piston and the bit shank, and a second pressure chamber that is opened and closed by movement of the bit shank and the piston and connects the first and second pressure chambers and the exhaust passage. 1 and a second exhaust valve, the hammer drill hits the bit shank by reciprocating movement of the piston, wherein the back head and the inner cylinder are integrally formed, and the back head has an axially penetrating A hammer drill characterized in that a guide is fixed, the tip of which forms the second exhaust valve so as to face the exhaust passage of the piston.