IE50337B1 - Self-tapping screws for plastics parts - Google Patents
Self-tapping screws for plastics partsInfo
- Publication number
- IE50337B1 IE50337B1 IE232480A IE232480A IE50337B1 IE 50337 B1 IE50337 B1 IE 50337B1 IE 232480 A IE232480 A IE 232480A IE 232480 A IE232480 A IE 232480A IE 50337 B1 IE50337 B1 IE 50337B1
- Authority
- IE
- Ireland
- Prior art keywords
- thread
- tip portion
- self
- screw
- notch
- Prior art date
Links
- 238000010079 rubber tapping Methods 0.000 title claims abstract description 17
- 229920003023 plastic Polymers 0.000 title description 3
- 239000004033 plastic Substances 0.000 title description 3
- 230000000694 effects Effects 0.000 description 2
- 238000004049 embossing Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
- F16B25/001—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed
- F16B25/0015—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed the material being a soft organic material, e.g. wood or plastic
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
- F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
- F16B25/0042—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw
- F16B25/0047—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw the ridge being characterised by its cross-section in the plane of the shaft axis
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
- F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
- F16B25/0078—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw with a shaft of non-circular cross-section or other special geometric features of the shaft
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
- F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
- F16B25/0084—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by geometric details of the tip
Abstract
The self-tapping screw with a sheet-metal-type screw-thread (4) and a conical tip portion (2) is characterised by the following features: the thread (4) pitch is between 2/3 and 3/4 of the core (1) diameter; the flank angle of the thread (4) is between 30 DEG and 50 DEG ; there is provided in the tip portion (2) a V cross-section cutting notch (5), the included angle ( gamma ) of which is 150 DEG to 160 DEG ; the bottom (6) of the notch (5) intersects the screw axis in or near the tip portion (2). The thread (4) flank angle is preferably 40 DEG . The tip portion (2) is formed as a truncated cone, the end diameter being 10 to 20% smaller than the core diameter. The angle of the notch bottom (6) in relation to the screw axis is 20 DEG to 35 DEG .
Description
The invention relates to a self-tapping screw for plastics parts with a sheet-metal-type screw-thread, and a conical tip portion.
Such a self tapping screw should have, on the one hand, good thread-forming properties and also a low screw-in moment; on the other hand, the overturn moment should be as large as possible. It should he possible to screw in the self-tapping screw several times, without splitting of the thread. This is important particularly for electrical appliances, for which special safety and testing regulations exist.
According to the invention there is provided a self-tapping screw for plastics parts with a sheetmetal-type screw-thread and a conical tip portion, characterised in that :a) the thread pitch is between 2/3 and 3/4- of the core diameter;
the flank angle of the thread is between 30° ,o
h)
c)
d) and 50 ;
there is provided, in the tip portion, a V-section cutting notch,'the included angle of which is 150° to 160°;
the bottom of the notch intersects the screw axis in or near the tip portion.
- 2 Desirably such a self-tapping screw should, require a screw-in moment as low as possible so that it can easily be screwed in, and in order to keep the wear of the screwdriver, particularly of the screwdriver blade, as low as possible.
On the other hand, the overturn moment should desirably be as large as possible, in order to guarantee high safety. In accordance with the relevant VDERichtlinien (VDE Recommendations) a testing torque is given, which secures a safe seat of the screw. A further demand consists in that the tapping screw guarantees a proper forced fit even after repeated unscrewing.
It has turned out that a preferred self-tapping screw embodying the invention excellently fulfills these demands. The thread has a rather pointed profile so that a good provision of the thread courses is guaranteed. The configuration of the cutting notch, in addition, guarantees a favourable thread forming. Particularly by the choice of the angle between the bottom of the notch and the screw axis it is possible to coordinate the cutting effect and the embossing effect with each other. The preferred screw embodying the invention has a comparatively small screw-in moment. For a 3.5 inm screw one requires a screw-in moment of
Ncm. The overturn moment is approximately 180 Ncm.
These values are to be considered as very favourable.
- 3 The invention will be described by way of example with reference to the accompanying drawings, wherein:
Fig. Ί is a side view of the preferred self-tapping screw embodying the invention;
Fig. 2 is another side view, turned by 90° with sectioned cutting tip;
Fig. 3 is a side view of the tip portion; and Fig. 4 is an end view of the tip portion.
The self-tapping screw as shown has a cylindrical core 1 and a tip portion 2, the latter being shaped like a truncated cone. The end diameter of the end face 3 of the tip portion 2 is approximately 10 to 20% smaller than the diameter of the core 1. A thread 4 is provided which is like a sheet metal screw thread.
The flank angle β is approximately 40°. Thus, the thread has a rather acute-angled profile. The thread pitch is between 2/3 and 3/4 of the core diameter.
Thus, the thread pitch is larger than in the case of the usual sheet metal screw thread.
A screwhead 7 is provided in the usual manner.
In the tip portion 2 there is provided a V-section cutting notch 5- The bottom 6 of the notch 5 intersects the screw axis in or near the tip portion 2 or in the end face 3. This means that the cutting edge cuts into the foot portion 2 rather deeply. The included angle of the notch is between 150° and 160°. The courses of
- 4 thread end within the tip portion 2.
The illustrated self-tapping screw embodying the invention has excellent thread-forming properties, because the thread is precut by the tip portion 2 and subsequently is shaped in an embossing manner. The screw-in moment is comparatively small. However, the overturn moment is very high. One easily achieves a ratio of the overturn moment to the screw-in moment of approximately 9·
Claims (5)
1. Claims:1. A self-tapping screw with a sheet-metal-type screw-thread and a conical tip portion, characterised in that: - a) the thread pitch is between 2/3 and 3/4 of the core diameter; b) the flank angle of the thread is between 30° and 50°; c) there is provided in the tip portion a V- ID section cutting notch, the included angle of which is 150° to 160°; d) the bottom of the notch intersects the screw axis in or near the tip portion. 2. A self-tapping screw according to claim 1, characterised in that the flank angle is 40°.
2. 3. A self-tapping screw according to claim 1 or claim 2, characterised in that the tip portion is formed as a truncated cone, the end diameter being 10 to 20% smaller than the core diameter.
3. 4. A self-tapping screw according to any one of claims 1 to 3, characterised in that the angle of the bottom of the notch in relation to the screw axis is 2(? to 35°.
4.
5. A self-tapping screw as claimed in Claim 1, D/7 substantially as herein described.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE7933213 | 1979-11-24 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| IE802324L IE802324L (en) | 1981-05-24 |
| IE50337B1 true IE50337B1 (en) | 1986-04-02 |
Family
ID=6709413
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| IE232480A IE50337B1 (en) | 1979-11-24 | 1980-11-10 | Self-tapping screws for plastics parts |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2063745B (en) |
| IE (1) | IE50337B1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4601625A (en) * | 1984-05-11 | 1986-07-22 | Illinois Tool Works Inc. | Self drilling threaded insert for drywall |
| US20040156696A1 (en) * | 2002-11-27 | 2004-08-12 | Grosch Gregory E. | Fastener for fiberglass and other composite structures |
| SE538636C2 (en) * | 2014-12-12 | 2016-10-04 | Essve Produkter Ab | Concrete screw |
-
1980
- 1980-10-31 GB GB8035166A patent/GB2063745B/en not_active Expired
- 1980-11-10 IE IE232480A patent/IE50337B1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB2063745A (en) | 1981-06-10 |
| IE802324L (en) | 1981-05-24 |
| GB2063745B (en) | 1983-02-16 |
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