WO1996019321A1

WO1996019321A1 - Adapter for axial percussion machines

Info

Publication number: WO1996019321A1
Application number: PCT/EP1995/004996
Authority: WO
Inventors: Helmut Österle; Erich Palm
Original assignee: Sfs Industrie Holding Ag
Priority date: 1994-12-21
Filing date: 1995-12-18
Publication date: 1996-06-27
Also published as: DE4445813A1; DE4445813C2; AU4387096A

Abstract

An adapter (12) for an axial percussion machine, such as an impact drilling machine (13), has two telescopic coupling members (14, 15) spring-loaded in the axial direction so as to slide inside each other and co-operate in the direction of rotation. One coupling member (14) is connected to the driven axis (17) of the impact drilling machine (13) and the other coupling member (15) receives a driving tool (18) for driving in a screw (1) into a workpiece (9). An adjustable depth stop (16) is arranged on the fixed part of the impact drilling machine (13). When driving in a screw, this adapter allows the drilling process to be assisted by an axial percussion force applied by the impact drilling machine (13). The depth stop (16) substantially reduces the axial compression force at the end of the drilling process, so that the axial force required for cutting the thread can be applied by a helical spring (23). This small axial force no longer causes the application of an axial percussion force by the impact drilling machine (13).

Description

Attachment for a machine working with an axial impact

The invention relates to an attachment for a machine working with an axial impact, such as a hammer drill or a rotary hammer, in which or in which the impact is transmitted to the output shaft under axial load.

Impact drills or rotary hammers are usually used - as the name suggests - with the help of an impact drill to make holes. The field of application is therefore limited to the production of holes in concrete or masonry. Even when drilling in wood, a drill without an axial impact is normally used.

So far, it has been considered absurd to use impact drills or rotary hammers in the drilling or hole-forming process for setting screws. Rather, special devices are used for setting such screws. For example, DE-AS 14 78 914 describes the setting of screws in such a way that, in addition to the rotary movement of the screw, an axial impact is also provided. The impact is only a single impact to make the hole. In US-PS 19 09 366 and in DE 31 21 275 A1 it is also described that an additional impact effect can be provided when screwing, for example at the end of the screwing process, or that the screw-in torque increases the screw-in torque for larger screw-in resistances can be provided or switched on, but no hole is produced by impact.

DE 43 01 610 A1 and DE 42 36 819 A1 show an impact wrench with deactivation of the impact effect or a combined impact drill and impact wrench with deactivation of the impact effect, but with which it is not possible to form self-drilling or self-piercing and to set thread-forming or tapping screws. This prior art is only concerned with activating an impact effect when drilling or screwing in screws. This impact can be switched off, but not for the transition to a subsequent thread forming or cutting process. From US-PS 40 30 383 it is also known to provide a depth stop for a screwdriver without a striking device, with which, as usual, the screwing-in movement is ended in good time.

The present invention has set itself the task of creating an attachment for a machine with which it is possible to set self-drilling or self-tapping and self-tapping or self-tapping screws.

According to the invention, it is proposed that two telescopically spring-loaded coupling elements that are slidably guided in the axial direction, but are constantly operatively connected to one another in the direction of rotation, wherein one coupling element can be coupled to the output axis of the machine and the other coupling element is the drive tool for a self-drilling or hole-forming and self-tapping or tapping screw or receives, and that an adjustable depth stop is arranged on the fixed part of the machine.

In the past, when placing screws, only care was taken to ensure that the drilling process ended before the thread forming process started. This is because the feed speed is significantly greater than the usual drilling feed, depending on the thread pitch. During the drilling process, a corresponding axial force and a corresponding torque have to be applied, whereas after the engagement of the first thread, practically only a corresponding torque has to be applied.

It has been shown that both the cutting effect of a drilling part of a screw and the formation of a hole-forming end section with non-cutting production of the hole on the screw, the drilling time can be significantly reduced if an axial impact effect, such as, for example, an impact drill or a hammer drill produces. In the subsequent thread forming or cutting process, however, it is undesirable to have an axial impact effect with a corresponding intensity, since in such a case the thread would be correspondingly widened in the axial direction.

Precisely by means of the attachment according to the invention, a possibility has been created that the rotary drive is kept constant until a screw is finally set, but the axial impact is switched off immediately after the drilling process or the hole-forming process has ended. Due to the adjustable depth stop, an exact setting is possible, so that the axial impact is switched off when the drilling or hole-forming process is completed. Nevertheless, sufficient further drive of the screws to be set is possible, because the two coupling members are slidably guided in the axial direction and are operatively connected to one another in the direction of rotation.

The device according to the invention is also particularly advantageous because the impact effect can be switched off immediately after a drill part or a hole-forming end section of the screw has completely penetrated and before the first thread engages in the bore or the hole. The more precise and timely the changeover is made by a depth stop, the more exact the seat of the screw that is then finally screwed in, since not only has an optimal bore or an optimal hole been produced, but also a particularly good mutual thread engagement between the workpiece and the the threaded shaft.

Advantageous embodiments of the invention form the subject of the subclaims. So it is provided in a constructively effective manner that the coupling members are designed as a bolt and a sleeve which engage coaxially with one another. This ensures exact axis alignment with the output axis of the machine, so that practically no wobble movements occur during the drilling process and also during the subsequent thread forming process.

So that even after using the depth stop and thus after the end of a corresponding contact pressure to trigger the axial impact, there is sufficient axial force to hold the screw securely in the drive tool, it is proposed that the opposite ends of the coupling members A stop flange is formed in each case and a screw spring is inserted between these two stop flanges. Thus, a corresponding axial force is always exerted on the screw, but this is not so great that the axial impact of the machine would come into action.

In this context, it is also advantageous if a helical spring is inserted between the coupling member following the output axis and the fixed part of the machine, the force of which is greater than the force of the coupling between the two used coil spring. This ensures that after the impact action has been switched off, it cannot be switched on again accidentally.

Another expedient embodiment is that one of the coupling members has an elongated hole or a groove and the other coupling member has a bolt or other driver which engages in the elongated hole or the groove. As a result, the rotational driving can be achieved in a mechanically simple manner, and the coupling members can be disassembled quickly by loosening the bolt or driver.

In an advantageous embodiment it is provided that the coupling members for the mutually guided mounting in the axial direction and for the positive mounting in the rotating direction have a cross-sectional shape corresponding to one another. With an appropriate construction, it is therefore possible to effect both the axial guidance and the rotational driving without additional structural measures. A particularly simple shape can be seen, for example, in the fact that a square or hexagonal shape is provided for the coupling members.

A structurally simple configuration of the attachment is also given when the depth stop is designed as a tube part coaxially enclosing the coupling members. In this way, on the one hand, the coupling members are covered to the outside, and, on the other hand, a large-area support of the depth stop is achieved. It is expedient if the depth stop is formed by two telescopically displaceable tube parts which can be displaced in the axial direction and can be mutually fixed in a desired position. With a construction of the depth stop designed in this way, simple adjustability to adapt to various circumstances is of course also possible.

The intention according to the invention is explained in more detail in the description below. Show it:

Figure 1 is a side view of a screw which is placed on a workpiece.

2 shows this screw after forming a hole and immediately before the start of the thread cutting or forming process; 3 shows an enlarged section through the workpiece and the screw, the mutual thread engagement being evident in particular;

4 shows a section through the header according to the invention;

Fig. 5 shows a section through the coupling members fully extended in the axial direction.

A hole-forming and thread-forming screw 1 shown in FIGS. 1 to 3 is provided with a non-cutting hole-forming end section 2 which runs out to a tip or a tip-like shape. Furthermore, there is a shaft section 4 provided with a thread 3 and an engagement section 5 for attaching or inserting a tool.

In the illustration, a screw 1 was assumed, which is self-tapping and self-tapping. There is therefore a non-cutting hole-forming end section 2 and a corresponding thread 3. The attachment described here can, however, be used for all other self-tapping and thread-forming screws, and, in addition, screws can be set in this way and with the device according to the invention, which are self-drilling and self-tapping. It does not matter whether the drilling process or the hole forming process or thread forming or cutting is carried out without cutting or machining. Experiments have shown that the attachment described here can also be used with particular success with self-tapping screws. It is irrelevant whether there is a drill tip made by forming or a corresponding drill bit at the free end of the screw. It has also been shown that with the attachment described here and especially also with a non-cutting hole-forming end section, screws can be made which are made entirely of stainless material. As a rule, an attempt is always made to produce at least the drill tip from a hardenable material in the case of an at least partially rustproof execution of screws in order to be able to apply the corresponding drilling performance. Therefore, expensive welding solutions for screws were always necessary.

By using the attachment described here, even screws with a hole-forming end section 2 or with other design configurations can be used, the screws being able to consist of a rustproof material. The attachment described here has the effect that the rotary drive for the screw 1 during the hole-forming process remains connected to the impact effect which is usual in machines such as impact drills or rotary hammers, in the axial direction 6. In addition to the rotary movement 7, the screw is also subjected to the axial impact 6. In this way, a corresponding hole 8 can be formed in the workpiece 9 in a work time that has been considerably shorter than in the past.

As soon as the hole 8 is completed, as can also be seen in FIG. 2, the impact effect is switched off by the attachment described here, so that only the rotary drive 7 is effective. This is the best variant for forming the thread 3 into the hole 8 in the workpiece 9, since this does not result in any axial impact or vibrating movements. The thread formed in the hole wall thus fits exactly on the surface of the thread 3 of the shaft 4.

In addition to the axial impact effect, it would be entirely possible to superimpose an impact effect which is exerted in the direction of rotation and which has practically no significance for the drilling or hole-forming process, but which can bring additional advantages with the subsequent thread-forming or cutting process.

In order to keep a corresponding axial range of motion, in which a changeover from the axial impact action to the elimination of this impact action has to take place, a short thread-free shaft portion 11 can be connected to the end portion 2. As soon as the end section 2 has finished forming the hole in the workpiece 9, there is an axial relief, since the thread-free shaft section 11 suddenly sags down through the hole 8 due to the axial contact force still exerted.

The attachment 12 described here is used for attachment to a machine 13 equipped with an axial impact effect, such as an impact drill or a corresponding hammer drill. In the case of the machine 13, an axially exerted impact effect is transmitted to the output axis with a corresponding axial load. The attachment 2 consists essentially of two coupling members 14 and 15 and an adjustable depth stop 16.

The two coupling members 14, 15 are guided telescopically and spring-loaded to one another in the axial direction. In the direction of rotation, however, these coupling members 14 and 15 are in constant operative connection. One coupling member 14 is connected to the output se 17 of the machine 13 can be coupled. The other coupling member 15 receives the drive tool 18 for a screw 1 or is directly provided with such a drive tool 18.

The coupling member 14 is in the form of a sleeve, whereas the coupling member 15 is in the form of a bolt. The two coupling members 14, 15 can thus engage in one another coaxially and are therefore also brought together accordingly in the axial direction. In order to bring about rotational driving between the two coupling members 14 and 15, the coupling member 15 has a groove 19 and the coupling member 14 has a bolt 20 which engages in this groove 19. A limited axial displaceability between the two coupling members 14 and 15 is thus ensured, but there is a permanent operative connection for the rotation. Of course, such a groove or a corresponding bolt can also be provided on the respective other coupling member 14 or 15, and it is also possible to provide an elongated hole in one of the coupling members 14, 15, into which a corresponding bolt is then provided intervenes. It would also be conceivable to design the coupling members for the mutually guided mounting in the axial direction to correspond to one another in cross-section, in order to ensure the form-fitting mounting in the direction of rotation by means of a special cross-sectional shape. For example, the coupling members 14, 15 designed as bolts and sleeves could have a square, hexagonal or generally non-circular cross-section.

The coupling members 14, 15 each have a stop flange 21, 22 at the ends facing away from one another, a helical spring 23 being inserted between these two stop flanges 21, 22. The two coupling members 14, 15 therefore always endeavor to move apart in the axial direction by the action of the helical spring 23. Therefore, when a screw 1 is inserted, there is always a corresponding, albeit low, contact pressure for the screw used, even if this contact pressure is so low that no axial impact is triggered on the machine 13. Another coil spring 26 is inserted between the flange 21 of the coupling member 14 and the fixed part of the machine 13. This helical spring 26 is designed to be stronger than the helical spring 23. An axial impact is only exerted with a correspondingly large axial contact force, ie only when the drilling or hole-forming process is carried out by the screw 1, with the two coupling members 14, 15 in this Position fully pushed into each other, as shown in Fig. 4. The depth stop 16 is designed as a coupling part 14, 15 coaxially enclosing tubular part. In this case, two telescopically displaceable tube parts 24, 25 are provided, which can be displaced relative to one another in the axial direction and can be mutually fixed in a desired position. An exact setting of the depth stop 16 is thus possible, since the two tube parts 24, 25 can only be pushed into one another axially and telescopically to the extent that it is desired to be preset. It can therefore be precisely determined when the hole-forming or drilling process of the screw 1 in the workpiece 9 has ended. As can be seen in FIG. 4, this is particularly advantageous in the case of very long screws 1. Here, for example, a screw is placed in an underlying workpiece 9 by an additional, thick insulation.

The possibility of setting the depth stop or corresponding fixing elements are not shown, since these are common with depth stops in various design variants. Due to the tubular design of the depth stop, the depth stop can be coupled to the corresponding head of the machine 13 in a simple manner.

Claims

1 . Attachment for a machine working with an axial impact action, such as a percussion drilling machine or a hammer drill, in which or in which the impact action is transmitted to the output shaft under axial load, characterized in that two spring-loaded, telescopically guided axially guided one against the other, In the direction of rotation, however, coupling members (14, 15) which are constantly connected to one another are provided, one coupling member (14) being able to be coupled to the output axis (17) of the machine (13) and the other coupling member (15) the drive tool (18) for a self-drilling or hole-forming and self-threading or tapping screw (1) or receives, and that an adjustable depth stop (16) is arranged on the fixed part of the machine (13).

2. Attachment according to claim 1, characterized in that the coupling members (14, 15) are designed as a bolt and a sleeve which engage coaxially with one another.

3. Attachment according to claim 1 or 2, characterized in that at the mutually opposite ends of the coupling members (14, 15) each have a stop flange (21, 22) and between these two stop flanges (21, 22) a coil spring (23) is used.

4. A header according to claim 3, characterized in that between the on the Abtriebs¬ axis (7) following coupling member (14) and the fixed part of the machine (13) a coil spring (26) is used, the force is greater than the force the coil spring (23) inserted between the two coupling members (14, 15).

5. Attachment according to one of claims 1 to 4, characterized in that one of the coupling elements (14, 15) has an elongated hole or groove (19) and the other coupling element (14, 15) one in the elongated hole or Has groove (19) engaging bolt (20) or other entrainers.

6. Attachment according to one of claims 1 to 4, characterized in that the coupling members (14, 15) have a mutually corresponding cross-sectional shape for mutually guided mounting in the axial direction and for positive locking mounting in the direction of rotation.

7. Attachment according to one of claims 1 to 6, characterized in that the Tiefenan¬ stop (16) as the coupling members (14, 15) is designed coaxially enclosing tubular part.

8. A header according to claim 7, characterized in that the depth stop (16) is formed by two telescopically displaceable tube parts (24, 25) which are axially displaceable relative to one another and can be fixed together in a desired position.