DE8717311U1 - Thread insert - Google Patents

Description

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Description Thread insert

The invention relates to a threaded insert according to the preamble of claim 1.

In the case of self-tapping thread inserts of the type mentioned above, the shape of the external thread is usually adapted to the material of the receiving hole into which the thread insert is to be screwed. When the thread insert is screwed into the receiving hole, the external thread of the thread insert cuts a thread into the receiving hole. The internal thread is then used to hold a screw bolt. The screw bolt is thus held more securely than if it were screwed directly into the receiving hole. This applies in particular if the material of the receiving hole is relatively soft, for example made of wood or plastic.

The internal thread of the threaded insert is usually a Horm thread, since the screw bolts to be screwed in usually also have a corresponding standard thread.

In the known thread inserts, the shape and orientation of the internal and external threads are determined independently of one another. The external thread is usually a standardized thread. For example, external threads with an external diameter between 10 mm and 36 mm each have a thread pitch of 1.5 mm, while an internal thread between M 6 and M 30.

The disadvantage of these thread inserts is that they are relatively heavy/ which is particularly disadvantageous*

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yirkt/ if the thread inserts are made of high-quality material * For example, threaded rods" sets with an internal thread M 6, an external diameter

Of 1Ö mm and a length vöfi 14 mm 0,36 Kg, If you

made of steel* One hundred pieces of the above

Threaded insert^ with an internal thread of M 30 and a length

of 40 mm already weigh 9.5 kg. This information refers to 100 pieces.

Another disadvantage of the known thread inserts is that they cannot be fitted into the 4^ ^B mounting hole. existing thread cutting machines due to the different pitches between internal and external threads.

The task is to improve the thread insert so that its weight is significantly reduced and it can also be used in mounting holes with existing thread cutting machines.

This problem is solved with the characterizing features of claim 1. Advantageous embodiments can be found in the subclaims.

Printed pipe threads are already known in which a thin-walled pipe is provided with a thread by pressing threads. For example, reference is made to the book Richter - von Voss - Koze "Bauelemente der Feinmechanik" 1959, Bild 262.5. In this case, internal and external threads are produced in the same operation by bending the pipe wall. However, such a pressed pipe thread is not comparable to a self-tapping thread insert, because the thin wall of the pipe makes it impossible to cut an internal thread into a receiving hole.

Examples of embodiments of the invention are explained in more detail below with reference to the drawings. They show:

fig· 1 a section through the wall of a first embodiment of a threaded insert;

Fig. 2 a corresponding section showing two further

Execution form of a: threaded insert And

Fig. 3 shows a further embodiment in cross-sectional position.

According to Fig. 1, the internal thread 1 and the external thread 2 have the same pitch T. Both threads 1/ 2 rise in the same direction. The pitch 3 of the internal thread 1 runs in the area of the thread tip 4 of the external thread 2. The internal thread is a standard thread 2, e.g. an M 4 thread with a pitch of 0.7 mm according to DIN 13. The external thread then also has a pitch of 0.7 mm, and is a special thread with a diameter of 6 mm* and a pitch of 0.7 mm.

The thread tip 4 of the external thread 2 has a flat 5. The thread tip 6 of the internal thread is also provided with a flat 7. The thread root 3 of the internal thread 1 has a round 8 and the thread root 9 also has a round 10. The flats 7 of the internal thread 1 are larger than the flats 5 of the external thread 2. The rounds 10 of the external thread 2 have a larger diameter than the rounds 8 of the internal thread 1.

In the above-mentioned conditions with an internal thread H 4 and an external thread 6 mm, each with a pitch of ö _F 7 mm, the distance between the thread root 3 of the internal thread 1 and the thread crest 4 of the external thread 2 is 1.04 mm. The smallest material thickness of the wall is in the direct connection between the thread roots 3,

9, which is 0.68 mm long. These are values without taking tolerances into account.

The threaded insert with the above dimensions provides a weight reduction of about 40X compared to a

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conventional threaded insert with an internal thread M 4 and an external thread with an outer diameter of 6.5 mm and a pitch of 0.75 mm.

A further reduction in wall thickness and thus in weight can be achieved if the conditions according to Fig. 2 are selected. First, the thread profiles shown in Fig. 2 in solid lines are explained. The difference from the thread profile arrangement according to Fig. 1 is that the radial distance of the thread root 3 of the internal thread 1 to the axis 11 of the thread insert is greater than the radial distance of the thread root 9 of the external thread 2. Otherwise, the conditions correspond to the

those according to Fig. 1. According to an example, interior

and external thread 1, 2 each have a pitch of 1.75 mm. The internal thread 1 is an M 12 thread, while the external thread 2 is a 14 mm thread. The material thickness between the thread flanks 12, 13 of the internal and external thread 1,2 is then 0.5 mm. The distance between the

tewindegrund 3 of the internal thread 1 and the flattened tip 4 of the external fewindes 2 is 0.9 mm. The external thread 2 is again a special thread

«it 14 mm diameter.

The threaded insert with the aforementioned external thread

2 Can also be provided with an internal thread 14, in which the radial distance of the thread base 15 to the thread insert axis 11 is even greater than in the example described above. The internal thread 14 can be an M 13 thread with a pitch of 1.75

&iacgr; mm. The distance between the thread flanks of the

Threads 2, 14 and the distance between the thread root and thread crest of the adjacent threads 2, 14 are each reduced to half of the above values.

The examples given refer to internal threads according to DIN 13. In the same way, thread inserts with a fine or special thread can also be manufactured as internal threads. It should be noted that the external thread has the same

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pitch/ both threads in the same direction seen in axial direction 11, the inner and outer threads are offset by half a pitch from each other*

In this way, threaded inserts can be manufactured that have a standard internal thread/ where the external thread has the same pitch as the internal thread/ but where the shape of the external thread depends on the application/ in particular on the material

uc r &eegr;&igr;&igr;&tgr;&pgr;&agr;&pgr;&pgr;&igr;&ngr;&ugr;&ugr;&igr;&igr;&tgr;&ugr;&igr;&igr;^ oujnt rmnrc rrtj &igr;/ ie rrgi 3 z^^^gx an external thread 2 with pointed thread tips and a flat thread base, which is particularly suitable for screwing into wood.

Claims (1)

ie· pm wM:claims 1. Threaded insert with an external thread cutting a thread into a receiving bore and an internal thread for receiving a threaded bolt, whereby the internal and external threads are rolled or cut, characterized in that the internal and external threads (1, 14; 2) rise in the same direction and have the same pitch (T> and the thread root (3) of the internal thread (1) in the Area of the thread crests (4) of the external thread (2). ( 2. Threaded insert according to claim 1, characterized in that the internal thread (1) is a norin thread. 3. Threaded insert according to claim 1 or 2, characterized in that the radial distance of the thread root (3) of the internal thread (1) to the axis of the threaded insert (11) is at least equal to the radial distance of the thread root (9) of the external thread (2) to this axis (11). 4. Thread insert according to one of claims 1 to 3, characterized in that the thread crests (4, 6) are flattened and the thread roots (3, 9) are rounded and the external thread (2) has the larger j . rounding (9) and the internal thread (1) has the larger flattening (7) than the other Thread (1, 2). i t