JP4539606B2 - Impact rotary tool that prevents steel balls from falling off - Google Patents

Description

  The present invention relates to an impact rotary tool, and more particularly to a technique for preventing a steel ball incorporated in a cam groove provided in a drive shaft and a hammer groove provided in a hammer from falling off.

The impact rotary tool is a rotary tool used when tightening or loosening screws, and generates a stronger torque by hitting when a load exceeding a certain level is applied. The structure used in the rotating tool to give the above functions, also because the same configuration as those conventional in the present invention, the following configuration will be described for a blow with reference to FIGS.

  As shown in FIG. 2, an annular hammer 2 is arranged inside the housing 9 so as to be fitted with the drive shaft 4, and the drive shaft 4 is provided with a cam groove 4 a in a substantially V shape. A hammer groove 2a is provided in the axial direction. Via the steel ball 1 inserted into the cam groove 4a and the hammer groove 2a, the rotational motion of the drive shaft 4 is transmitted to the hammer 2, and further the rotational motion is transmitted to the anvil 5 meshed with the hammer 2. When a certain load or more is generated in the anvil 5 during the operation and the rotation of the anvil 5 is slow, the cam groove 4a is positioned approximately at the center in the fitting portion between the steel ball 1 and the V-shaped cam groove 4a. The component force which pushes down the steel ball 1 which had been pushed along either groove direction arises. Here, which of the approximately V-shaped grooves along the cam groove 4 a depends on the rotation direction of the drive shaft 4.

  As shown in FIG. 3, the hammer 2 is pushed down on the drive shaft 4 in conjunction with the push-down of the steel ball 1, whereby the hammer 2 and the anvil 5 are disengaged. At this time, the hammer 2 is rotating, whereas the anvil 5 is stopped. The hammer 2 meshes with the anvil 5 again by being pushed back by the coiled spring 6. At this time, the hammer 2 gives a blow by its rotation to the stopped anvil 5. In this way, when a certain load or more is generated during work such as screw tightening, a stronger torque can be generated by striking.

  Even in the impact rotating tool of the conventional configuration, the hammering is realized by tightening or loosening the screw by using the steel ball in this way. When pulled down, there is a problem that the steel ball can easily fall off. This is because, in order to insert the steel ball into the cam groove and the hammer groove, a method is adopted in which the hammer is pulled down until the spring is substantially in close contact, and then the steel ball is inserted.

In order to solve the above problems, the one disclosed in Patent Document 1 inserts a push-up pin or the like after inserting a steel ball, thereby pushing up the seat of the coil spring in the close contact direction of the spring and moving the hammer backward. It was characterized by preventing the steel balls from falling off by limiting. However, with the above-described structure, the steel ball can surely be prevented from falling off, but the number of parts required for this purpose increases and the assembly process becomes complicated. In addition, the repairability is inevitably lowered, and secondary troubles such as a drop of the push-up pin are expected to occur.
Japanese Patent Laid-Open No. 5-228849

  The present invention has been made in view of the above points, and it is an object of the present invention to reliably prevent the falling of a steel ball, and to provide an impact rotary tool that is inexpensive and excellent in assemblability. It is.

In order to solve the above-described problems, the present invention is based on the concept that the cam groove for converting the rotational movement of the drive shaft into the backward movement of the hammer when the anvil reaches a certain load is used as the drive shaft, and the hammer groove as the hammer. The steel ball is provided so as to be fitted in the cam groove and the hammer groove, respectively, and a spring is provided for engaging the hammer and the anvil with striking again after releasing the mesh with the anvil by retreating the hammer. Covering the anvil, drive shaft, hammer, steel ball and spring with a housing, and from the interior parts arranged on the rear side of the hammer, a stopper is provided to prevent the steel ball from falling off the cam groove and hammer groove when the hammer moves back beyond a certain level. An impact rotary tool projecting parallel to the drive shaft toward the hammer, wherein the interior part houses a planetary mechanism, The topper is a ring-shaped piece that protrudes forward from the opening edge of the case so that it surrounds the outer periphery of the spring and receives the rear part of the hammer as a whole. The impact rotating tool.

By doing in this way, the stopper locks the rear part of the hammer before the hammer moves back to the steel ball dropping position, so that it is possible to reliably prevent the steel ball from dropping off. Further, since the stopper is provided integrally with the case housed in the housing, it is not necessary to add any special member, and the steel ball can be reliably prevented from falling off by a simple assembly process. Further, the stopper is formed in a ring shape that surrounds the outer periphery of the spring and receives the rear portion of the hammer as a whole, so that it is possible to prevent the energy received by the collision with the hammer from concentrating on a specific portion of the stopper. .

  According to the present invention, since the stopper locks the rear portion of the hammer before the hammer moves back to the steel ball dropping position, it is possible to reliably prevent the steel ball from dropping off.

Further, since the stopper is formed integrally with the case for housing the planetary mechanism, it is not necessary to assemble a special part, so that a product can be provided with excellent assemblability and at a low cost.

In addition, by forming a stopper that protrudes from the case that houses the planetary mechanism in a ring shape, it is possible to prevent deformation and breakage due to stress concentration on a part of the stopper and to withstand a large load It can be.

  The present invention will be described based on embodiments shown in the accompanying drawings. The impact rotary tool of the present invention generates a stronger torque by performing a hit when a load of a certain level or more is generated when tightening or loosening the screws. Since it has already been described in the description of, a brief description will be given below, and a configuration for preventing the falling of the internally mounted steel ball 1 will be described in detail.

  FIG. 1 shows an example in the embodiment of the present invention. As shown in the figure, a stopper 10 is projected from an interior part 12 disposed behind the hammer 2 toward the hammer 2 in parallel with the drive shaft 4. Before the hammer 2 reaches a later-described steel ball drop position 8, the rear portion is locked by the stopper 10, so that the steel ball 1 can be prevented from falling off.

  The stopper 10 is formed so as to surround the outer periphery of the spring 6 as shown in the figure, and is preferably formed in a ring shape so as to receive the rear part of the hammer 2 as a whole.

2 to 5 are longitudinal sectional views showing reference examples , and FIG. 6 is a sectional view taken along line AA in FIG.

  FIG. 2 shows a state in which the hammer 2 meshes with the anvil 5 to transmit the rotational motion of the drive shaft 4 to the anvil 5, and a force for retracting the hammer 2 through the steel ball 1 is applied to FIG. 2. As shown, the hammer 2 is retracted and disengaged from the anvil 5. In this state, the coiled spring 6 provided behind the hammer 2 is not yet in a close contact state, and therefore the steel ball 1 is not in a state of dropping off.

  If the hammer 2 is retracted until the spring 6 comes into close contact with the stopper 10 not provided, the spring 6 and the hammer 2 reach the positions indicated by the dotted lines in FIG. At this time, the rear part of the hammer 2 reaches the steel ball dropping position 8.

  However, in this example, a stopper 10 is projected from the inner surface of the housing 9 in a direction perpendicular to the drive shaft 4 between the position of the hammer 2 when the steel ball 1 is assembled and the position of the hammer 2 when the anvil 5 is engaged. Therefore, as shown in FIG. 5, the stopper 10 locks the rear part of the hammer 2 to prevent the hammer 2 from reaching the steel ball drop-off position 8. Furthermore, in the stopper 10, the strength of the stopper 10 is increased by projecting reinforcing ribs 14 in the backward direction of the hammer 2 as shown in FIG.

7 is another reference example , and FIG. 8 is a cross-sectional view taken along line BB in FIG. A pair of stoppers 10 project from the opposing positions on the inner surface of the housing 9 in a direction perpendicular to the drive shaft 4, and the stopper 10 engages the rear part of the hammer 2, so that the steel balls fall off the hammer 2. Reaching 8 is prevented.

It is a longitudinal section showing an example in an embodiment of the invention. It is a longitudinal cross-sectional view which shows a reference example , and is a state which the hammer and the anvil mesh | engaged. It is a longitudinal cross-sectional view which shows a reference example , and is the state which the hammer retracted. It is a longitudinal cross-sectional view which shows a reference example, and has shown the state which the hammer did not latch to a stopper and retracted to the steel ball drop-off position. It is a longitudinal cross-sectional view which shows a reference example , and is a state which the hammer contact | abutted with the stopper. It is the sectional view on the AA line in FIG. It is a longitudinal cross-sectional view which shows another reference example . It is the BB sectional view taken on the line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel ball 2 Hammer 2a Hammer groove 4 Drive shaft 4a Cam groove 5 Anvil 6 Spring 8 Steel ball dropping position 9 Housing 10 Stopper 12 Interior parts

Claims (1)

When the anvil reaches a certain load, the cam groove is used to convert the rotational movement of the drive shaft into the hammer's backward movement, the hammer groove is used as the hammer, and the steel ball is used as the cam groove and hammer groove. Provided to be fitted with each other, and provided with a spring for engaging the hammer and the anvil with striking again after releasing the mesh with the anvil by retracting the hammer, and further, the anvil, drive shaft, hammer, steel ball and spring A stopper that prevents the steel ball from falling out of the cam groove and the hammer groove when the hammer moves backwards beyond a certain level is projected in parallel to the drive shaft from the interior parts arranged behind the hammer toward the hammer. The impact rotary tool provided is a case in which the interior part houses the planetary mechanism, and the stopper surrounds the outer periphery of the spring. And so as to receive the hammer rear portion in its entirety, a rotary impact tool capable of preventing the steel ball dropping, characterized in that those from the opening edge of the case of a ring shape is protruded integrally forward.

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