JPS5932268B2 - Compressed air impact screwdriver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a compressed air percussion screwdriver having an integrated drive motor and a cam percussion mechanism, which is non-rotatably but axially slidably form-connected to the motor roller. The striking body, which is connected to the striking spindle, is adapted to be engaged with a pawl of the anvil configured as a striking spindle, and a pressure spring is tensioned between the striking body and the striking spindle, and the striking spindle is It is non-rotatably coupled to a camshaft disposed coaxially with the striking body, and this camshaft has an axial cam, which allows the striking body to move in the direction in which the claw engages. Regarding formal matters.

Known pneumatic percussion screwdrivers of this type have a vane motor configured as an external rotor motor.

The motor casing of this vane motor, which is designed as a rotor, is fixedly connected to the rotating striking body casing.

In this striking body housing, the striking body is guided in an axis-parallel groove in a form-fitting manner.

A non-rotatable connection between the percussion spindle and the camshaft is provided by a wrench-like flat surface formed on the camshaft engaging a corresponding inner surface of the percussion spindle.

A ball is arranged to transmit the action of the cam to the striking body.

The known pneumatic percussion screwdriver is operated by placing an aperture or an adapter with a hexagonal hole on the screw nut, which is connected to the percussion spindle.

When the motor is put into operation, it rotates the percussion body which, via the cam, entrains the camshaft, which in turn entrains the percussion spindle and thus the tool via a non-rotatable connection.

The nut is rotated and brought closer to the mounting surface.

When the nut contacts the support surface, it brakes the percussion spindle and thus the camshaft.

As the motor continues to rotate, a rotary movement occurs between the striking body carried by the motor and the camshaft braked by the tool, the cam striking the striking body and the pawl of the striking body striking the pawl of the striking spindle. and is moved in the axial direction until a rotational impact (torque generated by impact) is applied to this pawl using the weight of the striking body.

If a recoil of the striking body occurs, which is also transmitted to the motor rotor via the form-locking connection between striking body and striking body casing, the striking body is moved axially away from the striking spindle by means of a compression spring and is moved again in the meantime. It is accelerated again by the motor which begins to rotate and is again accelerated by the cam towards the striking spindle.

The disadvantage of this percussion screwdriver is that the percussion spindle and the camshaft are moved relative to each other in the axial direction, in which case the pressure spring forces the percussion spindle on the one hand and the percussion body and, via this, the camshaft on the other hand. It is to be pushed apart by an amount given by the dimensions of the casing and the dimensions of the bearing of the percussion screwdriver.

This dimension creates a long dimension that includes many manufacturing tolerances, so that the distance of the striking body from the striking spindle and thus the depth of engagement of the striking body pawl into the striking spindle pawl cannot be determined.

That is, as a result, the depth of engagement upon impact is insufficient, and the pawl is eventually damaged.

Another consequence of the relative movability of the percussion spindle and the camshaft is that the push spring pushes the percussion spindle forward in its casing bearing until the percussion spindle rests against the casing bearing with the flange; At the same time, the camshaft is pushed rearward via the striking body and the ball, thereby constantly applying pressure in the axial direction to the support of the camshaft.

As a result, the casing bearing of the percussion spindle and the camshaft or motor casing bearing are continuously subjected to pressure in the axial direction of the spring, which in turn increases friction losses and reduces the effective motor output.

Furthermore, the friction of one spindle is increased, so that if the resistance of the percussion spindle is slightly increased, for example by placing an adapter on a nut, the percussion spindle, and thus the camshaft, will continue to be affected by the percussion between the rotating percussion body and the cam. is braked to create a relative movement that releases the .

This so-called blank firing is inconvenient.

It is advantageous if the percussion screwdriver starts percussion only after the nut has been screwed in until it reaches the mounting surface.

The object of the present invention is to provide a percussion screwdriver of the type mentioned at the beginning, in which the pawls have a sufficient engagement depth, bearing losses are small, and dry driving can be avoided as much as possible. It is to be.

This problem has been solved in that the camshaft and the percussion spindle are connected to each other so that they cannot move axially.

As a result, the force of the pressure spring on the housing bearing of the percussion spindle and the bearing of the motor rotor or camshaft is reduced, so that longitudinal frictional forces in the bearings no longer become a problem.

The force of the compression spring is now closed via the percussion spindle, camshaft, cam and percussion body.

The rest interval of the striking pawl is therefore determined within a very narrow range, since it only depends on the dimensions of these parts and is independent of the dimensions of the motor rotor and the housing.

Furthermore, the tendency for the percussion screwdriver to dry out is reduced due to the elimination of axial friction in the bearing.

The connection between the percussion spindle and the camshaft can be a form-locking connection.

In this case, this form-locking connection can be obtained by means of transverse pins.

Furthermore, the connection can also be effected, for example, by a press fit, a shrink fit or a force-conducting connection using an adhesive.

Furthermore, this connection can also be made irreleasably, for example by welding.

It is also conceivable to configure the camshaft and the striking spindle in one piece.

In this case, it is advantageous to construct the striking body in multiple parts or to fix the cam cylinder on the cam shaft.

The invention will now be described with reference to the drawings: In the following description, "forward" refers to the direction towards the screw to be tightened, "rear" refers to the opposite direction;
``Downward'' refers to the direction toward the grip.

The only difference between the percussion screwdrivers shown in FIGS. 2, 3, 4 and 5 is the connection between the camshaft and the percussion spindle.

In these percussion screwdrivers, therefore, only these two parts have different symbols.

The percussion screwdriver 1 has a motor casing 2 with a compressed air motor 3 arranged inside and a handle 4 integrally molded in the lower part.

The grip 4 has a hose coupling 5 at its lower part for connecting a pressure conduit (not shown), and a tumbler switch 6 is arranged in the front part of the grip 4.

This tumbler switch 6 allows the compressed air motor 3 to be connected to the compressed air line.

A control housing 7 is screwed to the rear of the motor housing 2 .

The compressed air motor 3 is designed as an external rotor motor.

The compressed air motor 3 has an internal stator 8 screwed into a control housing 7, in which slots a number of blades 9 are guided in a radially slidable manner.

The forward end of the internal stator 8 terminates in a cylindrical pin 10 in which a radial ball bearing 11 is mounted.
is inserted.

A radial ball bearing 11 holds an external rotor 12 which forms the rotating casing of the compressed air motor and has a striking body casing 13 integrally molded at its front end.

The striking body casing is constructed as a hollow cylinder with an open front and has a guide groove 15 parallel to the axis in the cylindrical inner wall 14.
have.

A striking body 16 is slidably guided in the axial direction by corresponding guide teeth 17 in the guide groove 15 of the striking body casing 13 .

A bearing sleeve 18 is arranged coaxially with the motor at the front end of the motor housing 2, in which a percussion spindle 19 is mounted.

The bearing sleeve 18 has a flange 20 inside the motor casing 2 with a front limiting surface 21 arranged perpendicular to the axis and a rear limiting surface 22 also arranged at right angles to the axis.

The percussion spindle 19 has at its front end a conical part 23 which facilitates the mounting of a tool, for example a tool for tightening a nut.
have.

The percussion spindle 19 has a cut-off groove 24 at its rear, in which a snap ring 26 supported by an O-ring 25 and having a spring action in the radial direction is guided.

This snap ring 26 serves to secure the tool to the striking spindle.

Behind the parting groove 24, the percussion spindle has a square column 27 for receiving a tool.

The percussion spindle is supported in the bearing sleeve 18 in a cylindrical part 28 behind this square column part 27.

The percussion spindle has at its rear a substantially square-shaped flange 29 on the back side of which two mutually facing anvil projections 30 are integrally molded.

These anobile protrusions 30 are formed into a substantially rectangular parallelepiped shape and have parallel slopes 31 on both sides of the axis.

A blind hole 32 is formed at the rear end of the striking spindle.

A camshaft 340 and a cylindrical pin 33 are supported in this blind hole 32 .

Behind the pin 33, the camshaft 34 has a long cylindrical portion 35 having a somewhat larger diameter than the pin 33.

The cylindrical portion 35 has a large diameter cylindrical portion and a cam cylindrical body 36 at the rear end.

The transition between the cam cylinder 36 and the long cylinder 35 is strongly rounded and hollowed out.

An axial cam 37 is integrally formed on the front limiting surface 36' of the cam cylinder body 36.

The cam cylinder body 36 has a cylindrical notch 38 at its rear end, into which a non-ferrous metal bushing 39 is press-fitted.

Depending on this bushing 39, the camshaft is a cylindrical pin 10.
is supported on.

The striking body 16 is constructed as a hollow cylinder.

The striking body 16 has at the front two striking projections 40 facing the anvil projections of the striking spindle 19.

This striking projection 40 has a slope 41 corresponding to the slope 31 of the anvil projection.

The striking body has a cylindrical notch 42 from its front end face.

This recess 42 is delimited by a transverse wall 43 arranged in the rear end region of the striking body.

The horizontal wall 43 has a through hole 44 in the center.

A push spring 45 is inserted into the notch 42 .

This pressure spring 45 is tensioned between the side wall 43 of the striking body and the flange of the striking spindle.

A through hole 44 in the horizontal wall 43 is provided on the rear restriction surface of the striking body 16.
A pocket 46, which is closed to the outside and the front, is molded in the area, extending over a large part of the outer circumference.

A steel ball 47 is sandwiched between the pocket 46 of the striking body and the front limiting surface 36' of the cam cylinder 36 of the camshaft.

The percussion spindle 19 and the camshaft 34 are non-rotatably connected to each other.

For this purpose, in the known screwdriver, the camshaft 34 has, immediately after the pin 33, two driving surfaces 48, which resemble outwardly directed spanner surfaces.

Opposite this driving surface 48, the percussion spindle is provided with two inwardly directed driving surfaces 49.

The driving surfaces 48, 49 transmit torque between the camshaft and the percussion spindle, whereas camshaft and percussion spindle are independent in the axial direction.

First embodiment of the impact screwdriver of the present invention (Fig. 3)
In this case, the camshaft 134 does not have a pin at the front, but is inserted with a constant diameter into a hole 50 in the center of the percussion spindle 119 and is moved non-rotatably and at the same time in the axial direction by means of a transverse pin 51. Impossibly combined with a striking spindle.

In the second embodiment shown in FIG.
4 and the percussion spindle 219 is provided.

For this purpose, the camshaft has a pin 54 at its front end.

This pin 54 is inserted into a hole 55 in the percussion spindle.

This pin has a large diameter relative to the hole and is either pressed into this hole or the pin is inserted into the hole of a cooled and heated percussion spindle and then shrink-fitted at temperature equilibrium. A power transmission connection is created between the camshaft and the percussion spindle.

Furthermore, the pin 54 can be inserted into the hole 55 with a slip fit and fixed with adhesive.

In FIG. 5, the permanent connection between the camshaft 334 and the striking pin 319 is shown.

This connection is indicated by a welded seam.

Electric resistance welding is particularly recommended at the connection point between the camshaft and the percussion spindle because the welding points are difficult to access.

Furthermore, it is also conceivable to configure the striking pin and the camshaft in one piece.

In this case, the impacting body may be constructed from multiple parts as shown in FIG. 6, and the halves of the impacting body divided by a cut plane including the rotation axis may be held together by a contraction ring 56, or the impacting body halves may be held together by a contraction ring 56 as shown in FIG. As shown in FIG. 2, the impacting body 16 is integrated, and the cam cylinder body 436 can be fixed to the cam shaft 434 later with, for example, a pin.

By confining the force of the push spring in the group consisting of the rotating part, the striking spindle, the camshaft and the striking body, the axial force on the screwdriver bearing is removed and friction losses are reduced, thereby increasing the power output. is increased, and the tendency of the screwdriver to dry drive is reduced.

Furthermore, in this case the engagement depth of the percussion pawl on the anvil pawl is significantly narrower than in the case of known percussion screwdrivers, so that the risk of damage due to collisions of the pawls is reduced.

[Brief explanation of the drawing]

The drawings show several embodiments of the invention, the first
The figures are a side view of a known percussion screwdriver, FIG. 2 is an enlarged sectional view of an intermediate portion of the known percussion screwdriver, FIG. 3 is an enlarged sectional view of the percussion spindle and camshaft connected by a pin, and FIG. 4 5 is a cross-sectional view showing a percussion spindle and a camshaft that are connected in a power transmission manner, FIG. FIG. 7 shows a sectional view of the camshaft and the multi-part striking body; FIG. 7 shows a sectional view of the integrally connected percussion spindle, camshaft and fixed cam cylinder; FIG. DESCRIPTION OF SYMBOLS 1... Impact screw driver, 2... Motor casing, 3... Compressed air motor, 4... Grip,
5... Hose joint, 6... Tumbler switch, 7...
...Control casing, 8...Internal stator, 9...
Blade, 10... Pin, 11... Radial ball bearing, 12... External rotor, 13... Impact body casing, 14... Inner wall, 15... Guide groove, 16...
- Impact body, 17... Guide tooth, 18... Bearing sleeve, 19... Impact spindle, 20... Flange, 2
DESCRIPTION OF SYMBOLS 1... Restriction surface, 22... Restriction surface, 23... Conical part, 24... Parting groove, 25... 01J ring, 26...
・Snap ring, 27... Square prism part, 28... Cylindrical part, 29... Flange, 30... Anobile projection,
31... slope, 32... blind hole, 33... pin, 3
4... Cam shaft, 35... Cylindrical portion, 36... Cam cylindrical body, 37... Axial cam, 38... Notch,
39... Non-ferrous metal bushing, 40... Hitting protrusion, 4
1...Slope, 42...Notch, 43...Side wall, 4
4... Through hole, 45... Pressing spring, 46... Pocket, 47... Steel ball, 48... Entrainment surface, 49...
Engagement surface, 50...hole, 51...horizontal pin, 54...
Pin, 119... Hitting spindle, 134... Camshaft, 219... Hitting spindle, 234... Camshaft, 319... Hitting spindle, 334... Camshaft,
434...Cam shaft, 436...Cam cylindrical body.

Claims (1)

[Scope of Claims] 1. A compressed air percussion screwdriver having an integrated drive motor and a cam percussion mechanism, the percussion screw being connected to the motor rotor by a form-locking connection in a rotationally immovable but axially slidable manner. The body is adapted to be engaged with a pawl of an anvil configured as a spindle, and a pressure spring is tensioned between the striking body and the striking spindle, and the striking spindle is arranged coaxially with the striking body. The camshaft is non-rotatably coupled to a camshaft, which has an axial cam, and the axial cam allows the striking body to move in the direction in which the pawl engages the camshaft. A pneumatic percussion screwdriver, characterized in that the percussion spindle 34 and the percussion spindle 19 are connected to each other so as not to be axially movable. 2. A pneumatic percussion screwdriver according to claim 1, wherein the camshaft and the percussion spindle are connected to each other by a form-locking connection. 3 The shape connection between the camshaft and the striking spindle is the horizontal pin 51
A compressed pneumatic percussion screwdriver according to claim 2, which is manufactured by K.K. 4. Compressed pneumatic percussion screwdriver according to claim 1, in which the camshaft 34 and the percussion spindle 19 are connected to each other by a power transmission connection. 5. The compressed air percussion screwdriver according to claim 4, wherein the power transmission connection between the camshaft and the percussion spindle is achieved by press fitting. 6. A compressed air percussion screwdriver according to claim 4, wherein the power transmission connection between the camshaft and the percussion spindle is achieved by a shrink fit. 7. The compressed air percussion screwdriver according to claim 4, wherein the power transmission connection between the camshaft and the percussion spindle is performed by adhesive bonding. 8. The compressed air percussion screwdriver according to claim 1, wherein the camshaft and the percussion spindle are irreleasably coupled. 9. The camshaft and the striking spindle are integrated.
A compressed air percussion screwdriver according to claim 8. 10. The compressed air percussion screwdriver according to claim 9, wherein the percussion body is composed of multiple parts. 11. A compressed air impact screwdriver according to claim 9, wherein the cam cylindrical body is fixed to the cam shaft.