GB2235744A - Self-tapping fastener - Google Patents
Self-tapping fastener Download PDFInfo
- Publication number
- GB2235744A GB2235744A GB9018840A GB9018840A GB2235744A GB 2235744 A GB2235744 A GB 2235744A GB 9018840 A GB9018840 A GB 9018840A GB 9018840 A GB9018840 A GB 9018840A GB 2235744 A GB2235744 A GB 2235744A
- Authority
- GB
- United Kingdom
- Prior art keywords
- thread
- conical
- fastener
- angle
- sub
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000010079 rubber tapping Methods 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 description 7
- 239000000463 material Substances 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 5
- 239000011295 pitch Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- SGTNSNPWRIOYBX-UHFFFAOYSA-N 2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl](methyl)amino}-2-(propan-2-yl)pentanenitrile Chemical compound C1=C(OC)C(OC)=CC=C1CCN(C)CCCC(C#N)(C(C)C)C1=CC=C(OC)C(OC)=C1 SGTNSNPWRIOYBX-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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
- F16B25/0036—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
- F16B25/0042—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
- F16B25/0057—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 screw having distinct axial zones, e.g. multiple axial thread sections with different pitch or thread cross-sections
-
- 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
- F16B25/0073—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 characterised by its pitch, e.g. a varying pitch
Abstract
The screw-in torque of a self-tapping screw is minimised by the screw having a cylindrical shank portion 3, a conical portion 4 leading in to the shank portion, and a thread 7 on the shank and the conical portion. The conical portion 4 has a plurality of first conical sub-portions (4') having a first cone angle uniformly distributed about the circumference of the fastener and a plurality of second conical sub-portions (4") with a second cone angle smaller than the first cone angle and arranged between the first conical sub-portions (4'). <IMAGE>
Description
SELF- TAPPING FASTENER The invention refers to a self-tapping fastener
comprising a cylindrical shank portion, a conical portion leading into the shank portion and a thread on the shank and the conical portion.- Screws, self-drilling screws, screw taps etc. are known which have a reduced screw-in torque owing to specific threads, notches in the threads, pitches and lubricant coatings. This effect is desired in particular in connection with thick and hard workpiece material, e.g. with screws being treated against a2=csim by electro galvanizing.
However, the known measures are not satisfac- tory for specific purposes so that the screw portions may occur in use.
0 breakage of From the German patent specification 31 17 624 a univer sal screw has become known wherein the thread of a first portion adjacent the screw tip has a plurality of turns with constant height and a vertex angle which is smaller than that of the following shank portion. In the starting portion,the vertex angle may be 20 to 300 whereas it is approximately 40' to 601 in the shank portion. For this reason,the screw-in torque for the starting or first por-. tion and the screw portion following the first portion is relatively low. However, this can be improved because the thread depth of the first and the main portion is the same although the first portion effects the essential deformation to generate a female thread. The variable vertex or thread angle cannot effect the desired reduction of the screw-in torque for the first or starting portion.
According to this invention a self-tapping fastener comprises a cylindrical shank portion, a conical portion leading in to the shank portion having a plurality of first conical sub-portions uniformly distributed about its circumference and having a first cone angle, and a plurality of second conical sub-portions located between the first sub-portions and having a second cone angle which is less than the first coneangle, and a thread formed on the shank portion and the conical portion.
im The fastener according to the invention has f irst and second conical sub- portions adjacent its tip having different cone angles. The second conical sub-portions having the smaller conical angle extend radially farther than the first conical sub-portions so that the thread in the conical portion is mainly formed in the second conical subportions. The thread profile of the first conical portions reduces more with increasing distance from the junction between shank and conical portion than-on the second coni- cal sub-portions because the first conical sub-portions have a smaller radial extent. Thus, the thread on the second conical sub-portions around the circumference of the fastener protrudes more than that on the first conical sub-portions. This causes a considerably reduced screw-in torque of the fastener if the conical portion is threaded into a preformed hole, and mainly the thread portions on the second conical sub-portions engage the wall of the hole. The thread in the conical portion, thus, defines a tapping thread which gradually forms,the female thread in the work piece. The thread on the shank portions def ines a supporting thread which supports the screw in the completely formed female thread.
The thread of the f astener according to the invention f o37 example can be made by thread rolling. To simplify the manufacture the thread can be provided with an invariable thread angle and a constant pitch. The thread can have different geometries which, however, must be fully formed only in the shank portion.
In a preferred embodiment of the invention, the vertex of the thread in the conical portion forms a conical subportion tapering towards the screw tip, the conical angle thereof being larger than the conical angle of the second conical sub-portion. Thus, the depth of the thread decreases on its conical sub-portion towards the screw tip so that particularly low screw-in torques are achieved. With gradual tapping of a thread groove in the work piece as the scnw is s=azd-in,dth the depth of the engaging thread portion gradually increasiM so that approximately a constant screwin torque is achieved until the engagement of a support thread of the shank portionis complete.
The thread can be simply made by thread rolling.
According to a f urther embodiment of the invention, the fastener each has two f irst and two second conical subportions which can be simply manufactured. According to a further preferred embodiment, the second conical subportions extend approximately about 401' of the circum- ..Wference of the fastener which effects a considerable reduction of the screw-in torque in conjunction with a favourable thread tapping effect.
In another preferred embodiment of the invention,the first conical subportions are connected with a plug portion opposite to the shank portion, the second conical sub portions running out in the cylindrical circumference of the plug portion so that a full cylindrical guide plug portion is formed. The guide plug centers the screw upon insertion into a preformed bore made by a drilling tool or a drill tip of the fastener so that a centered and fully formed thread groove is formed in the work piece.
According to a further preferred embodiment of the invention, the thread has a thread angle on the conical portion which is smaller than the angle of the thread of the shank portion. The thread on the conical portion, thus, defines a tapping thread which solely preforms the thread groove.
The f inal shape of the thread groove is made when the shank portion is screwed into the bore because the enlarged thread angle effects a further flow of material.
is z Thus, the tapping of the thread groove extends over a larger range of the thread so that a further reduction of the screw-in torque is achieved. The thread angle can change in the connection portion between the conical portion and the shank portion so that the shank portion can be completely provided with a support thread.
A further reduction of the screw-in torque is achieved when the thread on the shank portion adjacent to the conical portion has a flow thread having a thread angle smaller than the thread angle of the support thread adjacent the flow thread. By this the thread groove in the work piece is preformed by the tapping thread on the conical portion. The thus preformed groove subsequently is further tapped to a small extent by the flow thread and finally formed by the engagement of the support thread and the change of the thread angle associated therewith. The extent of the -thread tapping of a larger portion of the thread reduces the screw- in torque, with the flow thread and the support thread participating with the force transfer between thread groove and thread approximately at a uniform amount to secure the screw against pull out.
In a practical embodiment of the invention, the tapping thread in the conical portion or the flow thread in the shank portion, respectively, has a thread angle in the range of 30 to 451, preferably a thread angle of 400, and the support thread in the shank portion has a thread angle of approximately 600. The thread angle ofthe tapping thread and of the f low thread may be equal, or may differ in the indicated range.
If the thread at the vertex or the root, respectively, is rounded an improved flow of material can be achieved upon tapping of the thread groove. Besides a reduction of the tapping torque also a f.riction welding between screw and workpiece is reduced or avoided Finally, the thread can have a constant pitch by which the. manufacture of the fastener is simplified.
A particular example of a fastener in accordance with this invention will now be described with reference to the accompanying drawings; in which:- 8 Fig. 1 shows a fastener in side view including tapping thread, flowing thread and support thread; Fig. 2 a f ront view of the blank f or the f astener of Fig. 1; and - Fig. 3 the blank of Fig. 2 in a side view.
The screw illustrated in Fig. 1 has a raised head 1 including a recess 2 for the positive engagement by a rotary tool. The screw head 1 is connected with a shank portion 3 which is joined by a conical portion 4 which runs out in a plug portion 5. At the screw tip the plug portion 5 is joined by a guide portion 6.
Conical portion 4 and shank portion 3 have a thread 7 which forms a tapping thread on the conical portion 4 having the length y and a flow thread on the shank portion having the exte nt z and a support thread having the extent x. In the embodiment example shown the thread on shank portion 3 has a triangular profile. In the conical portion 4 the vertex of thread 7 defines a conical subportion 8 having a cone angle larger than the cone angle of conical portion 4 so that the depth of the thread on the conical portion 4 decreases towards the screw tip.
n i 9 The thread angle o4,, 1 of thread 7 is about 400 in the conical portion 4 and in the area of the f low thread on shank portion 3. In the area of the support thread on shank portion 3 the thread has a thread angle 06,. 2 of 5 approximately 600.
5- In the application, f irst the guiding plug portion 6 is inserted into a preformed bore in the workpiece. If turned the thread engages first with a small depth, with a progressive tapping of the thread groove also the depth in the conical portion 4 increases. After the tapping thread on the conical portion 4 is completely screwed in the engagement of the flow thread on shank portion 3 effects a uniform flow of the material about the preformed thread groove by which stresses in the workpiece are eliminated.
Finally, the thread groove obtains its final shape by the engagement of the support thread and the associated change of the thread angle of 401 to 601.
Prior to the formation of thread 7 a screw blank 9 is 20 manufactured as shown in Fig. 2 and 3. The screw blank has already screw head 1 and plug portion 6. A prepared shank portion 31 has a diameter somewhat larger than that of the final shank portion 3 because material is displaced upon rolling of thread 7. The same is true for the preformed conical portion 41 and 411, with 41 designating first conical sub-portions and 411 second conical sub-portions which are arranged around the circumference of the screw alternatingly and uniformly distributed. The conical sub- >-W, portions 41 and 411 start at the junction between shank portion 31 and conical portion 41, 41' and have different longitudinal extensions because they have different cone angles. The first conical sub-portions 41 are contiguous to plug portion 4, the second conical sub-portions 411 running out on the cylindrical circumference of plug portion 5.
During the rolling of a thread by means of cylindrical rolling tools on screw blank 9 a thread is made having the features shown in Fig. 1.
A screw according to the invention generates a positively shaped thread groove into which a commercial screw, e.g.
with a metric thread can be screwed having a normal thread corresponding to that of the support thread.
0 JP - 11
Claims (12)
1. A self-tapping fastener comprising a cylindrical shank portion, a conical portion leading in to the shank portion having a plurality of first conical sub-portions uniformly distributed about its circumference and having a first cone angle, and a plurality of second conical sub-portions located between the first sub-portions and having a second cone angle which is less than the first coneangle, and a thread formed on the shank portion and the conical portion.
2. A fastener according to claim 1, wherein the vertex of the thread in the conical portion forms a conical sub-portion tapering towards a tip of the fastener and having a cone angle which is larger than that of the second conical sub-portion.
3. A fastener according to claim 1 or 2, wherein two first and two second conical sub-portions are provided.
4. A fastener according to any one of the preceding claims, wherein the second conical sub-portions extend to about 401 of the circumference of the fastener.
5. A fastener according to any one of the preceding claims, wherein the leading end of the fastener is formed as a plug portion having a cylindrical shell, the second sub-portions running cut into the shell, with a continuous cylindrical lead-in plug portion being formed adjacent the screw tip.
6. A fastener according to any one of the preceding claims, wherein the thread on the conical portion has a thread angle which is smaller than the thread angle on the shank portion.
7. A fastener according to any one of the preceding claims, wherein the thread on the shank portion has a flow thread having a thread angle adjacent the conical portion, the thread angle of the flow thread being 1 12 smaller than that of a support thread between the f low thread and a head of the fastener.
8. A fastener according to claims 6 or 7, wherein the thread on the conical portion and the flow thread in the shank portion, respectively, have a thread angle in the range of 30' to 451, and the support thread has a thread angle of substantially 600.
9. A fastener according to claim 8, wherein the thread on the conical portion and the flow thread have a thread angle.of substantially 400.
10. A fastener according to any one of the preceding claims, wherein the thread is rounded on its vertex and its root.
11. A fastener according to any of the preceding claims, 15 wherein the thread had a constant lead.
12. A self-tapping fastener substantially as described with reference to the accompanying drawings.
Published 1991 at The Patent Office. State House. 66/71 HWhHolborn. LondonWClR47?. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwndclinfach. Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques lid. St Mary Cray. Kent
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19893929332 DE3929332A1 (en) | 1989-09-04 | 1989-09-04 | SELF-FORMING SCREW |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9018840D0 GB9018840D0 (en) | 1990-10-10 |
| GB2235744A true GB2235744A (en) | 1991-03-13 |
| GB2235744B GB2235744B (en) | 1992-12-09 |
Family
ID=6388598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9018840A Expired - Fee Related GB2235744B (en) | 1989-09-04 | 1990-08-29 | Self-tapping fastener |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE3929332A1 (en) |
| GB (1) | GB2235744B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5304024A (en) * | 1991-03-18 | 1994-04-19 | Adolf Wurth Gmbh & Co. Kg | Screw, method and rolling die for the production thereof |
| US5704750A (en) * | 1997-01-16 | 1998-01-06 | Ford Global Technologies, Inc. | Multiple use screw with tapered threads |
| EP1319134A1 (en) * | 2000-09-19 | 2003-06-18 | Textron Inc. | Improved masonry anchor device |
| WO2016048822A1 (en) * | 2014-09-22 | 2016-03-31 | Simpson Strong-Tie Company, Inc. | Variable thread fastener |
| US9482258B2 (en) | 2012-05-10 | 2016-11-01 | Simpson Strong-Tie Company, Inc. | Fastener with multiple threaded regions |
| US9523383B2 (en) | 2013-03-26 | 2016-12-20 | Simpson Strong-Tie Company, Inc. | Variable thread fastener |
| US9651079B2 (en) | 2013-03-21 | 2017-05-16 | Simpson Strong-Tie Company, Inc. | Fastener with prolate cross-section |
| US9784297B2 (en) | 2013-08-30 | 2017-10-10 | Faurecia Interieur Industrie | Threaded fastening element |
| US11181138B2 (en) | 2013-03-26 | 2021-11-23 | Simpson Strong-Tie Company, Inc. | Variable thread knurl fastener |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19753755C2 (en) * | 1997-12-04 | 2001-07-05 | Deha Ankersysteme | Low-slip screw connection for rods in construction with geometrically defined counter |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1142175A (en) * | 1966-05-10 | 1969-02-05 | Eaton Yale & Towne | Self-tapping screw |
| US4069730A (en) * | 1976-06-03 | 1978-01-24 | Wales-Beech Corporation | Thread-forming screw |
| US4235149A (en) * | 1978-08-17 | 1980-11-25 | Veldman Donald R | Self-thread creating fastener and method and apparatus for making the same |
-
1989
- 1989-09-04 DE DE19893929332 patent/DE3929332A1/en not_active Withdrawn
-
1990
- 1990-08-29 GB GB9018840A patent/GB2235744B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1142175A (en) * | 1966-05-10 | 1969-02-05 | Eaton Yale & Towne | Self-tapping screw |
| US4069730A (en) * | 1976-06-03 | 1978-01-24 | Wales-Beech Corporation | Thread-forming screw |
| US4235149A (en) * | 1978-08-17 | 1980-11-25 | Veldman Donald R | Self-thread creating fastener and method and apparatus for making the same |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5304024A (en) * | 1991-03-18 | 1994-04-19 | Adolf Wurth Gmbh & Co. Kg | Screw, method and rolling die for the production thereof |
| US5704750A (en) * | 1997-01-16 | 1998-01-06 | Ford Global Technologies, Inc. | Multiple use screw with tapered threads |
| EP1319134A1 (en) * | 2000-09-19 | 2003-06-18 | Textron Inc. | Improved masonry anchor device |
| EP1319134A4 (en) * | 2000-09-19 | 2004-12-29 | Textron Inc | Improved masonry anchor device |
| USRE42207E1 (en) | 2000-09-19 | 2011-03-08 | Asia Fastening (Us), Inc. | Masonry anchor device |
| US9482258B2 (en) | 2012-05-10 | 2016-11-01 | Simpson Strong-Tie Company, Inc. | Fastener with multiple threaded regions |
| US10480559B2 (en) | 2012-05-10 | 2019-11-19 | Simpson Strong-Tie Company, Inc. | Fastener with head cutting structure |
| US9651079B2 (en) | 2013-03-21 | 2017-05-16 | Simpson Strong-Tie Company, Inc. | Fastener with prolate cross-section |
| US9523383B2 (en) | 2013-03-26 | 2016-12-20 | Simpson Strong-Tie Company, Inc. | Variable thread fastener |
| US11181138B2 (en) | 2013-03-26 | 2021-11-23 | Simpson Strong-Tie Company, Inc. | Variable thread knurl fastener |
| US9784297B2 (en) | 2013-08-30 | 2017-10-10 | Faurecia Interieur Industrie | Threaded fastening element |
| WO2016048822A1 (en) * | 2014-09-22 | 2016-03-31 | Simpson Strong-Tie Company, Inc. | Variable thread fastener |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9018840D0 (en) | 1990-10-10 |
| DE3929332A1 (en) | 1991-03-07 |
| GB2235744B (en) | 1992-12-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20020829 |