CA2793494C - Self-tapping screw - Google Patents
Self-tapping screw Download PDFInfo
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- CA2793494C CA2793494C CA2793494A CA2793494A CA2793494C CA 2793494 C CA2793494 C CA 2793494C CA 2793494 A CA2793494 A CA 2793494A CA 2793494 A CA2793494 A CA 2793494A CA 2793494 C CA2793494 C CA 2793494C
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- screw
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- 238000010079 rubber tapping Methods 0.000 title claims abstract description 76
- 238000005520 cutting process Methods 0.000 claims abstract description 126
- 238000005553 drilling Methods 0.000 claims abstract description 125
- 230000007704 transition Effects 0.000 claims description 8
- 239000002023 wood Substances 0.000 abstract description 27
- 230000009471 action Effects 0.000 abstract description 8
- 230000009916 joint effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 23
- 230000008569 process Effects 0.000 description 23
- 239000002184 metal Substances 0.000 description 13
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000005253 cladding Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 230000035515 penetration Effects 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229920002522 Wood fibre Polymers 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000002025 wood fiber Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000004575 stone Substances 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
- F16B25/10—Screws performing an additional function to thread-forming, e.g. drill screws or self-piercing screws
- F16B25/103—Screws performing an additional function to thread-forming, e.g. drill screws or self-piercing screws by means of a drilling screw-point, i.e. with a cutting and material removing action
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Drilling Tools (AREA)
- Connection Of Plates (AREA)
Abstract
A self-tapping screw is described with a drilling part and a shaft (14) which is provided with a thread (12) and a core diameter (Dk). The drilling part has a drilling tip (20) which is arranged eccentrically in relation to a longitudinal axis of the screw, and is configured as a sickle tip (101) which has a primary cutting edge (30) and a secondary cutting edge (40). The primary cutting edge (30) is formed by the intersection of a cutting surface (60) and a main free surface (90) and extends from the drilling tip (20) parallel to the longitudinal axis of the screw. The secondary cutting edge (40) is formed by the intersection of the cutting surface (60) and an auxiliary free surface (70) and extends obliquely with respect to the longitudinal axis of the screw over the width of the drilling part. A hole with the core diameter (Dk) can be produced by way of the screw, into which the thread (12) cuts a counterthread. As a result of the joint action of the primary and secondary cutting edges (30, 40), the fibres are severed during the drilling operation when a workpiece is made from wood, so that the screw develops practically no splitting action.
Description
Self-Tapping Screw Description The invention relates to a self-tapping screw with a drilling part and a shaft which is provided with a thread and a core diameter, wherein the drilling part comprises a lateral surface and a drilling tip arranged eccentrically in relation to a longitudinal axis of the screw and at least one first cutting edge which extends obliquely with respect to the longitudinal axis of the screw, and wherein the drilling part is configured as a sickle tip; the invention relates particularly to the use of such screws in wood.
A self-tapping screw of the above-mentioned type, in which, however, the drilling part is not configured as a sickle tip, is known from the document EP 1430 227 B 1.
Said known screw is neither intended nor suitable for use in wood. It is used to attach a panel-type object to a substructure, where the substructure is usually made of metal, often from profile portions made of thin sheet metal. The panel-type object usually is a cladding panel made from ceramic, fiber cement, stone or a similar brittle material for producing a housing cladding.
As a result of solar irradiation, the housing cladding on the substructure migrates. Therefore, through bores are used in the cladding plates, which receive the securing screws with sufficient play. For this purpose, one usually uses self-tapping screws which are provided with wings that protrude freely, obliquely to the screw axis, and, if desired, broaden the through hole. The screw according to the above-mentioned document is configured particularly to produce, without the assistance of such wings, a through hole which receives the shaft of the screw with play, in particular only in the panel-type object and not in the thinner metal substructure. For this purpose, its drilling part has Replacement sheet ( Rule 26)
A self-tapping screw of the above-mentioned type, in which, however, the drilling part is not configured as a sickle tip, is known from the document EP 1430 227 B 1.
Said known screw is neither intended nor suitable for use in wood. It is used to attach a panel-type object to a substructure, where the substructure is usually made of metal, often from profile portions made of thin sheet metal. The panel-type object usually is a cladding panel made from ceramic, fiber cement, stone or a similar brittle material for producing a housing cladding.
As a result of solar irradiation, the housing cladding on the substructure migrates. Therefore, through bores are used in the cladding plates, which receive the securing screws with sufficient play. For this purpose, one usually uses self-tapping screws which are provided with wings that protrude freely, obliquely to the screw axis, and, if desired, broaden the through hole. The screw according to the above-mentioned document is configured particularly to produce, without the assistance of such wings, a through hole which receives the shaft of the screw with play, in particular only in the panel-type object and not in the thinner metal substructure. For this purpose, its drilling part has Replacement sheet ( Rule 26)
2 a drilling tip which is arranged eccentrically in relation to the longitudinal axis of the screw, and a cutting edge extending obliquely from the drilling tip over the entire width of the drilling part.
The drilling tip forms, from the start of the drilling process on, a centering tip for the screw, as a result of which the screw is positioned obliquely from the start of the drilling process on. The hole which is produced in the panel-type object is not cylindrical, due to the circular motion of the drilling part, instead it is conically broadened and its diameter increases in the direction of the substructure. When the drilling tip finally reaches the bottom side of the substructure, the hole has been broadened to its maximum size.
Although the screw according to the document EP 1430 227 B1 can be used to produce a through hole having the core diameter of the thread of the screw, this succeeds only if an axial separation between the drilling tip and an intersection of the cutting edge and of the longitudinal axis of the screw is adapted to the thickness of the substructure to be drilled through.
Accordingly, with the known screw, such a hole can be produced only in a relatively thin workpiece or substructure, that is, for example, in thin sheet steel.
Another self-tapping screw, which also has an eccentrically arranged drilling tip, is known from the document US 4 568 229 A. On both sides of the drilling tip, the screw has two cutting edges which are located substantially on a diameter and which cut a hole whose diameter is substantially smaller than the core diameter of the thread. This known screw is also not intended for use in wood, but is intended rather for being screwed into a substructure made of sheet steel.
A self-tapping screw of the above-mentioned type is known from the document DE
735 U1. This document starts from the prior art, which pertains to screwing the screw in sheet metal, wherein no bore in the sheet metal is required, because the bore required for screwing the Replacement sheet ( Rule 26)
The drilling tip forms, from the start of the drilling process on, a centering tip for the screw, as a result of which the screw is positioned obliquely from the start of the drilling process on. The hole which is produced in the panel-type object is not cylindrical, due to the circular motion of the drilling part, instead it is conically broadened and its diameter increases in the direction of the substructure. When the drilling tip finally reaches the bottom side of the substructure, the hole has been broadened to its maximum size.
Although the screw according to the document EP 1430 227 B1 can be used to produce a through hole having the core diameter of the thread of the screw, this succeeds only if an axial separation between the drilling tip and an intersection of the cutting edge and of the longitudinal axis of the screw is adapted to the thickness of the substructure to be drilled through.
Accordingly, with the known screw, such a hole can be produced only in a relatively thin workpiece or substructure, that is, for example, in thin sheet steel.
Another self-tapping screw, which also has an eccentrically arranged drilling tip, is known from the document US 4 568 229 A. On both sides of the drilling tip, the screw has two cutting edges which are located substantially on a diameter and which cut a hole whose diameter is substantially smaller than the core diameter of the thread. This known screw is also not intended for use in wood, but is intended rather for being screwed into a substructure made of sheet steel.
A self-tapping screw of the above-mentioned type is known from the document DE
735 U1. This document starts from the prior art, which pertains to screwing the screw in sheet metal, wherein no bore in the sheet metal is required, because the bore required for screwing the Replacement sheet ( Rule 26)
3 screw in is produced by the screw itself. It is also considered disadvantageous that, in the known self-tapping screws, the screw tip deviates during the cutting process, to the extent that the sheet metal has not center-punched before screwing the screw in. Furthermore, it is considered disadvantageous that a screw connection produced by means of a known self-tapping screw often does not have the necessary pull out strength, and the screws can often be used only with small sheet metal thicknesses. This document therefore relates to the problem of producing a self-tapping screw which avoids these disadvantages, and particularly also nearly rules out a deviation of the screw during the screwing in process and produces a screw connection with high pull out strength. This self-tapping screw has a tip which has no radius and which is arranged with slight offset to the side relative to the axis of the shaft. This self-tapping screw therefore should have the advantage that, due to the offsetting of the screw with respect to the axis of the screw shaft during the screwing of the screw into the sheet metal, a sheet metal rim hole (formation of flanges) is obtained, so that the thread cuts not only into the sheet metal but also into this sheet metal rim hole, as a result of which the engagement surface for the screw and thus also the pull out strength are considerably increased. Due to the tip without radius, the drilling process in the case of this self-tapping screw occurs already at the time of the first contact of the tip with the sheet metal in question, so that a deviation of the screw can be ruled out with certainty. This known self-tapping screw is thus not intended for use in wood and it does not have the usual properties of a wood screw.
If a usual wood screw is screwed into wood, there is always the risk of the wood splitting.
From the document DE 20 2007 018 179 U1, a screw is known which, in order to prevent the splitting of the wood, has a scraper groove extending from the screw tip over a portion of the length of the shaft. The scraper groove should favor the immediate engagement of the thread in Replacement sheet ( Rule 26)
If a usual wood screw is screwed into wood, there is always the risk of the wood splitting.
From the document DE 20 2007 018 179 U1, a screw is known which, in order to prevent the splitting of the wood, has a scraper groove extending from the screw tip over a portion of the length of the shaft. The scraper groove should favor the immediate engagement of the thread in Replacement sheet ( Rule 26)
4 the wood and prevent the splitting of the wood. Using such a screw with a scraper groove, it is indeed possible to effectively reduce the tendency to split; however, it is very expensive to manufacture such a screw with a scraper groove.
The problem of the invention is to produce a self-tapping screw which can be screwed into wood with reduced splitting action, and which at the same time should be easier to manufacture, wherein the usual properties of a wood screw, such as, for example, a high pullout value, a low penetration torque, and a good setting behavior should remain ensured, and wherein the drilled hole should have the core diameter of the thread of the screw.
This problem is solved according to the invention in that the drilling part is configured as a sickle tip and has a second cutting edge which forms a primary cutting edge, and which is formed substantially by the intersection of a cutting surface and of a main free surface, and in that it extends from the drilling tip predominantly parallel to or essentially parallel to the longitudinal axis of the screw, in that the first cutting edge is a secondary cutting edge formed by the intersection of the cutting surface and of an auxiliary free surface, said second cutting edge extending from the drilling tip obliquely with respect to the longitudinal axis of the screw over the width of the drilling part, and in that the drilling tip lies on an imaginary circle around the longitudinal axis of the screw whose diameter is equal to or substantially equal to the core diameter.
By means of the sickle tip, the screw according to the invention drills a hole whose diameter corresponds to the core diameter of the thread. This ensures the desired high pullout value. Since the sickle tip has a primary cutting edge located on the outside, which severs the wood fibers, the splitting action is considerably reduced compared to the prior art, if not eliminated completely. The screw according to the invention requires a low penetration torque, Replacement sheet ( Rule 26)
The problem of the invention is to produce a self-tapping screw which can be screwed into wood with reduced splitting action, and which at the same time should be easier to manufacture, wherein the usual properties of a wood screw, such as, for example, a high pullout value, a low penetration torque, and a good setting behavior should remain ensured, and wherein the drilled hole should have the core diameter of the thread of the screw.
This problem is solved according to the invention in that the drilling part is configured as a sickle tip and has a second cutting edge which forms a primary cutting edge, and which is formed substantially by the intersection of a cutting surface and of a main free surface, and in that it extends from the drilling tip predominantly parallel to or essentially parallel to the longitudinal axis of the screw, in that the first cutting edge is a secondary cutting edge formed by the intersection of the cutting surface and of an auxiliary free surface, said second cutting edge extending from the drilling tip obliquely with respect to the longitudinal axis of the screw over the width of the drilling part, and in that the drilling tip lies on an imaginary circle around the longitudinal axis of the screw whose diameter is equal to or substantially equal to the core diameter.
By means of the sickle tip, the screw according to the invention drills a hole whose diameter corresponds to the core diameter of the thread. This ensures the desired high pullout value. Since the sickle tip has a primary cutting edge located on the outside, which severs the wood fibers, the splitting action is considerably reduced compared to the prior art, if not eliminated completely. The screw according to the invention requires a low penetration torque, Replacement sheet ( Rule 26)
5 because the sickle tip with the drilling tip is set initially in the center of the hole to be produced on the wood, and, during the drilling process, with formation of a small hole whose diameter rapidly increases, it migrates outward, and in the end produces a hole with the core diameter of the thread. The primary cutting edge which is located on the outside and at least substantially parallel to the longitudinal axis of the screw, and which is not present in any screw of the prior art, cuts radially, i.e., it cuts the material away toward the outer edge of the hole, whereas the secondary edge cuts axially, i.e., it cuts away the material radially inward of the drilling tip inside the hole, and in the process it directs the drilling tip in a guided manner outward. The compressive force required to achieve progression of the drilling decreases continuously from the start of the drilling process, until the diameter of the hole has reached the core diameter, which also contributes considerably to reducing the tendency to split.
The self-tapping screw according to the invention, owing to the drilling tip arranged radially outside, owing to the primary cutting edge located outside, and owing to the secondary cutting edge extending from the drilling tip obliquely over the width of the drilling part, strives to drill a hole with the core diameter of its thread. Although the screw according to the invention is set with the drilling tip in the drill hole axis on the wood, with increasing depth of the screw penetrating in the wood, the longitudinal axis of the screw and the drill hole axis increasingly approach a position in which they coincide. This is a surprising action for the person skilled in the art, in view of the above-described prior art according to the document EP
143 0 227 B 1, wherein the drilling tip in the panel to be secured maintains its central position until the substructure is reached, and in that manner produces the broadening of the through hole to a diameter which is substantially greater than the core diameter of the thread of the screw. In contrast, the drilling tip of the self-tapping screw according to the invention from the start of the Replacement sheet ( Rule 26)
The self-tapping screw according to the invention, owing to the drilling tip arranged radially outside, owing to the primary cutting edge located outside, and owing to the secondary cutting edge extending from the drilling tip obliquely over the width of the drilling part, strives to drill a hole with the core diameter of its thread. Although the screw according to the invention is set with the drilling tip in the drill hole axis on the wood, with increasing depth of the screw penetrating in the wood, the longitudinal axis of the screw and the drill hole axis increasingly approach a position in which they coincide. This is a surprising action for the person skilled in the art, in view of the above-described prior art according to the document EP
143 0 227 B 1, wherein the drilling tip in the panel to be secured maintains its central position until the substructure is reached, and in that manner produces the broadening of the through hole to a diameter which is substantially greater than the core diameter of the thread of the screw. In contrast, the drilling tip of the self-tapping screw according to the invention from the start of the Replacement sheet ( Rule 26)
6 drilling process on migrates outward from its at first central position by a distance which is equal to half the core diameter, which has the consequence that, in spite of the drilling tip being arranged eccentrically, a hole is drilled whose diameter is equal to the core diameter. In the self-tapping screw according to the invention, as mentioned, this is achieved in that the primary cutting edge located outside and the oblique secondary cutting edge both extend from the drilling tip.
A drilling process with a self-tapping screw always starts with the setting of the drilling tip on the surface of the component to be drilled through. The smaller the force which is needed at the beginning of the drilling process is, and the more obliquely the screw can be set without slipping off, the better the setting behavior of the screw is. The self-tapping screw according to the invention has a very good setting behavior, it ensures a high pullout force and a low penetration torque, and it can be manufactured cost effectively with low splitting force.
Advantageous embodiments of the invention are the subject matters of the dependent claims.
In an embodiment of the self-tapping screw according to the invention, the drilling tip is formed by the intersection of the cutting surface, of the auxiliary free surface and of the main free surface. Since the primary cutting edge and the secondary cutting edge extend from the drilling tip, this design means that all the cutting edges at the sickle tip of the self-tapping screw according to the invention abut against one and the same surface, that is the cutting surface, which facilitates the production of the cutting edges.
In a further embodiment of the self-tapping screw according to the invention, the secondary cutting edge forms an angle of up to 40 degrees with a longitudinal axis of the screw.
Replacement sheet (Rule 26)
A drilling process with a self-tapping screw always starts with the setting of the drilling tip on the surface of the component to be drilled through. The smaller the force which is needed at the beginning of the drilling process is, and the more obliquely the screw can be set without slipping off, the better the setting behavior of the screw is. The self-tapping screw according to the invention has a very good setting behavior, it ensures a high pullout force and a low penetration torque, and it can be manufactured cost effectively with low splitting force.
Advantageous embodiments of the invention are the subject matters of the dependent claims.
In an embodiment of the self-tapping screw according to the invention, the drilling tip is formed by the intersection of the cutting surface, of the auxiliary free surface and of the main free surface. Since the primary cutting edge and the secondary cutting edge extend from the drilling tip, this design means that all the cutting edges at the sickle tip of the self-tapping screw according to the invention abut against one and the same surface, that is the cutting surface, which facilitates the production of the cutting edges.
In a further embodiment of the self-tapping screw according to the invention, the secondary cutting edge forms an angle of up to 40 degrees with a longitudinal axis of the screw.
Replacement sheet (Rule 26)
7 This results in a sickle tip with defined setting behavior, and a particularly effective action of the main and the secondary cutting edges.
In a further embodiment of the self-tapping screws according to the invention, the lateral surface of the drilling part has a diameter which is equal to or substantially equal to the core diameter. In this case, the drilling part transitions into the shaft of the screw, so that only a small force needs to be applied for screwing the screw into the hole with the core diameter.
In a further embodiment of the self-tapping screw according to the invention, the main free surface is a portion of the lateral surface of the drilling part. In this case, no additional production steps for the main free surface are required, because the lateral surface, which is preferably cylindrical, is present in any case.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip is substantially parallel to the longitudinal axis of the screw. This can be the most advantageous design for a given application depending on the type of wood to be drilled through.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip at a right angle to the cutting surface takes up half the core diameter.
This makes it possible, in the case of a great length of the main and secondary cutting edges, to have sufficient clearance in the area of the drilling tip to remove the borehole cuttings.
In a further embodiment of the self-tapping screw according to the invention, the cutting surface contains the longitudinal axis of the screw. In this case, the sickle tip at a right angle to the cutting surface can take up up to half of the core diameter.
In a further embodiment of the self-tapping screw according to the invention, the cutting surface forms an angle of up to 30 degrees with the longitudinal axis of the screw. As a result, a drilling performance corresponding to the type of wood to be drilled through can be chosen.
Replacement sheet ( Rule 26)
In a further embodiment of the self-tapping screws according to the invention, the lateral surface of the drilling part has a diameter which is equal to or substantially equal to the core diameter. In this case, the drilling part transitions into the shaft of the screw, so that only a small force needs to be applied for screwing the screw into the hole with the core diameter.
In a further embodiment of the self-tapping screw according to the invention, the main free surface is a portion of the lateral surface of the drilling part. In this case, no additional production steps for the main free surface are required, because the lateral surface, which is preferably cylindrical, is present in any case.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip is substantially parallel to the longitudinal axis of the screw. This can be the most advantageous design for a given application depending on the type of wood to be drilled through.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip at a right angle to the cutting surface takes up half the core diameter.
This makes it possible, in the case of a great length of the main and secondary cutting edges, to have sufficient clearance in the area of the drilling tip to remove the borehole cuttings.
In a further embodiment of the self-tapping screw according to the invention, the cutting surface contains the longitudinal axis of the screw. In this case, the sickle tip at a right angle to the cutting surface can take up up to half of the core diameter.
In a further embodiment of the self-tapping screw according to the invention, the cutting surface forms an angle of up to 30 degrees with the longitudinal axis of the screw. As a result, a drilling performance corresponding to the type of wood to be drilled through can be chosen.
Replacement sheet ( Rule 26)
8 In a further embodiment of the self-tapping screw according to the invention, the primary cutting edge is inclined in an area adjacent to the drilling tip by a small angle of up to 10 degrees toward the longitudinal axis of the screw against a surface line of the lateral surface. This design can be used to further improve the drilling process depending on the type of wood to be drilled through.
In a further embodiment of the self-tapping screw according to the invention, the cutting surface is oriented in the longitudinal direction of the screw and adjacently to the drilling tip, parallel to or substantially parallel to the longitudinal axis of the screw.
This can be used to further improve the drilling process compared to the previous design, depending on the type of wood.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip at a right angle to the cutting surface takes up less than half the core diameter. As a result, the available length of the main and secondary cutting edges is indeed reduced, but the clearance for the removal of the borehole cuttings is increased.
In a further embodiment of the self-tapping screw according to the invention, the drilling part has, in an area adjacent to the drilling tip, an outer diameter which is smaller by a small distance than the core diameter of the shaft. Depending on the type of wood to be drilled through, this design as well can be used to improve the drilling process.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip at a right angle to the cutting surface takes up more than half the core diameter. Although this results in less clearance for the removal of the borehole cuttings, it allows a greater length of the main and secondary cutting edges.
Replacement sheet (Rule 26)
In a further embodiment of the self-tapping screw according to the invention, the cutting surface is oriented in the longitudinal direction of the screw and adjacently to the drilling tip, parallel to or substantially parallel to the longitudinal axis of the screw.
This can be used to further improve the drilling process compared to the previous design, depending on the type of wood.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip at a right angle to the cutting surface takes up less than half the core diameter. As a result, the available length of the main and secondary cutting edges is indeed reduced, but the clearance for the removal of the borehole cuttings is increased.
In a further embodiment of the self-tapping screw according to the invention, the drilling part has, in an area adjacent to the drilling tip, an outer diameter which is smaller by a small distance than the core diameter of the shaft. Depending on the type of wood to be drilled through, this design as well can be used to improve the drilling process.
In a further embodiment of the self-tapping screw according to the invention, the sickle tip at a right angle to the cutting surface takes up more than half the core diameter. Although this results in less clearance for the removal of the borehole cuttings, it allows a greater length of the main and secondary cutting edges.
Replacement sheet (Rule 26)
9 In a further embodiment of the self-tapping screw according to the invention, the cutting surface is hollowed out inward starting from a surface line of the drilling part, so that the primary cutting edge is parallel to or substantially parallel to the longitudinal axis of the screw over only a portion of its length. Depending on the type of bore to be produced and the type of wood to be drilled through, this design as well can be used to improve the drilling process.
In a further embodiment of the self-tapping screw according to the invention, the primary cutting edge extends in its area directly adjacent to the drilling tip obliquely with respect to the longitudinal axis of the screw, and it transitions at the corner into an area in which it extends parallel to or substantially parallel to the longitudinal axis of the screw.
This design results in an additional cutting edge coming into play in the area of the primary cutting edge, which can have an advantageous effect on the drilling process.
In a further embodiment of the self-tapping screw according to the invention, at the transition into the shaft on the cutting surface, radii, phases or cavities are formed. This facilitates the removal of the borehole cuttings and the production of the sickle tip, and it prevents the occurrence of spikes at the transition between the shaft and the drilling part.
In a further embodiment of the self-tapping screw according to the invention, the thread starts on a shaft portion facing the drilling tip and adjacent to the drilling part. As a result, the splitting action is further reduced.
Embodiment examples of the invention are described in greater detail below in reference to the drawings.
Figures lid show a first embodiment of a self-tapping screw according to the invention with a sickle tip parallel to the longitudinal axis of the screw;
Replacement sheet ( Rule 26)
In a further embodiment of the self-tapping screw according to the invention, the primary cutting edge extends in its area directly adjacent to the drilling tip obliquely with respect to the longitudinal axis of the screw, and it transitions at the corner into an area in which it extends parallel to or substantially parallel to the longitudinal axis of the screw.
This design results in an additional cutting edge coming into play in the area of the primary cutting edge, which can have an advantageous effect on the drilling process.
In a further embodiment of the self-tapping screw according to the invention, at the transition into the shaft on the cutting surface, radii, phases or cavities are formed. This facilitates the removal of the borehole cuttings and the production of the sickle tip, and it prevents the occurrence of spikes at the transition between the shaft and the drilling part.
In a further embodiment of the self-tapping screw according to the invention, the thread starts on a shaft portion facing the drilling tip and adjacent to the drilling part. As a result, the splitting action is further reduced.
Embodiment examples of the invention are described in greater detail below in reference to the drawings.
Figures lid show a first embodiment of a self-tapping screw according to the invention with a sickle tip parallel to the longitudinal axis of the screw;
Replacement sheet ( Rule 26)
10 Figures 2a-2d show a second embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is inclined against the longitudinal axis of the screw;
Figures 3a-3d show a third embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is narrower than in the first and the second embodiment examples;
Figures 4a-4d show a fourth embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is less narrow than in the third embodiment example;
Figures 5a-5d show a fifth embodiment example of the self-tapping screw according to the invention, wherein the sickle tip with its cutting surface is inclined against the longitudinal axis of the screw;
Figures 6a-6d show a sixth embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is configured to be flatter than in the previous embodiment examples;
Figures 7a-7d show a seventh embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is slightly blunted; and Figures 8a-8d show representations in order to explain the drilling process using the example of the self-tapping screw according to Figures 1 a-1 d.
Figure 1, consisting of Figures 1 a-1 d, shows a first embodiment example of a self-tapping screw according to the invention, marked 10 as a whole in each case in Figure 1 and in all the additional figures. The screw 10 is made of metal. The head of the screw 10 is only visible in Figure 8, where it is marked 11. In each of Figures 1-7, only the end of the screw 10 facing the Replacement sheet ( Rule 26)
Figures 3a-3d show a third embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is narrower than in the first and the second embodiment examples;
Figures 4a-4d show a fourth embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is less narrow than in the third embodiment example;
Figures 5a-5d show a fifth embodiment example of the self-tapping screw according to the invention, wherein the sickle tip with its cutting surface is inclined against the longitudinal axis of the screw;
Figures 6a-6d show a sixth embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is configured to be flatter than in the previous embodiment examples;
Figures 7a-7d show a seventh embodiment example of the self-tapping screw according to the invention, wherein the sickle tip is slightly blunted; and Figures 8a-8d show representations in order to explain the drilling process using the example of the self-tapping screw according to Figures 1 a-1 d.
Figure 1, consisting of Figures 1 a-1 d, shows a first embodiment example of a self-tapping screw according to the invention, marked 10 as a whole in each case in Figure 1 and in all the additional figures. The screw 10 is made of metal. The head of the screw 10 is only visible in Figure 8, where it is marked 11. In each of Figures 1-7, only the end of the screw 10 facing the Replacement sheet ( Rule 26)
11 head 11 is visible. On the represented end, the screw 10 is provided with a drilling part 100, which is configured as a sickle tip in each one of the represented embodiment examples of the invention. In the first embodiment example, shown in Figure 1, the sickle tip overall is marked 101. The screw 10 has a shaft 14 provided with a thread 12 and a core diameter Dk.
Figure 1 shows, in Figure 1 a, the self-tapping screw 10 according to the invention in an axial top view onto the drilling part 100 in the direction of an arrow A' in Figure 1 b, in Figure 1 b the drilling part 10 and an adjacent portion of the shaft 14 of the screw 10 in a side view in the direction of an arrow B' in Figure 1 c, in Figure 1 c the drilling part 100 and the adjacent shaft portion in a view rotated by 90 with respect to the representation in Figure 1 b, and in Figure 1 d the drilling part 100 and the adjacent shaft portion in a perspective representation. The additional embodiment examples of the self-tapping screw according to the invention are shown in Figures 2-7, in each case in identical views.
The drilling part 100 has a lateral surface 22 which, in the embodiment example represented here, is a circular cylindrical lateral surface. The screw 10 has a longitudinal axis 80.
Its drilling tip 20 is arranged eccentrically. The sickle tip 101 of the drilling part 100 of the screw is provided with a primary cutting edge 30 arranged radially outside, and formed by the intersection of a cutting surface 60 and a main free surface 90. The primary cutting edge 30 extends from the drilling tip 20, in the embodiment example according to Figure 1, parallel to the longitudinal axis 80. The cutting surface 60, with an auxiliary free surface 70, which is shown in Figures 1 c and 1 d, forms a secondary cutting edge 40. The secondary cutting edge 40 extends from the drilling tip 20 obliquely with respect to the longitudinal axis 80 over the width of the drilling part 100, which can be seen in Figure lb. The drilling tip 20 lies on an imaginary circle around the longitudinal axis 80 of the screw 10. The diameter of this circle is equal to the core Replacement sheet (Rule 26)
Figure 1 shows, in Figure 1 a, the self-tapping screw 10 according to the invention in an axial top view onto the drilling part 100 in the direction of an arrow A' in Figure 1 b, in Figure 1 b the drilling part 10 and an adjacent portion of the shaft 14 of the screw 10 in a side view in the direction of an arrow B' in Figure 1 c, in Figure 1 c the drilling part 100 and the adjacent shaft portion in a view rotated by 90 with respect to the representation in Figure 1 b, and in Figure 1 d the drilling part 100 and the adjacent shaft portion in a perspective representation. The additional embodiment examples of the self-tapping screw according to the invention are shown in Figures 2-7, in each case in identical views.
The drilling part 100 has a lateral surface 22 which, in the embodiment example represented here, is a circular cylindrical lateral surface. The screw 10 has a longitudinal axis 80.
Its drilling tip 20 is arranged eccentrically. The sickle tip 101 of the drilling part 100 of the screw is provided with a primary cutting edge 30 arranged radially outside, and formed by the intersection of a cutting surface 60 and a main free surface 90. The primary cutting edge 30 extends from the drilling tip 20, in the embodiment example according to Figure 1, parallel to the longitudinal axis 80. The cutting surface 60, with an auxiliary free surface 70, which is shown in Figures 1 c and 1 d, forms a secondary cutting edge 40. The secondary cutting edge 40 extends from the drilling tip 20 obliquely with respect to the longitudinal axis 80 over the width of the drilling part 100, which can be seen in Figure lb. The drilling tip 20 lies on an imaginary circle around the longitudinal axis 80 of the screw 10. The diameter of this circle is equal to the core Replacement sheet (Rule 26)
12 diameter Dk in the embodiment example according to Figure 1. The drilling tip 20 is formed by the intersection of the cutting surface 60, of the auxiliary free surface 70 and of the main free surface 90, so that the primary cutting edge 30 and the secondary cutting edge 40 abut against one and the same surface, in particular the cutting surface 60.
The secondary cutting edge 70, according to the representation in Figure lb, forms an angle y with the longitudinal axis 80 of the screw 10, which can be up to 40 degrees. The lateral surface 22 of the drilling part 100, according to the representation in Figure 1 c, has a diameter Da which is equal to the core diameter Dk in the embodiment example according to Figure 1. The main free surface 90 is a portion of the lateral surface 22 of the drilling part 100, and thus a cylindrical surface here. The sickle tip 101 is substantially parallel to the longitudinal axis 80 of the screw 10, and at a right angle to the cutting surface 60 it takes up half of the core diameter Dk according to the representation in Figure 1 c, wherein, in the embodiment example according to Figure 1, the cutting surface 60 contains the longitudinal axis 80 of the screw 10.
The screw 10 according to the invention can be manufactured by hot or cold forming and/or machining by cutting a cylindrical starting material or a screw blank.
The type of manufacture is not important for understanding the invention.
In a panel-type workpiece 120 indicated in Figure 8, the above described design of the screw 10 serves the purpose of producing a through hole, which receives the shaft 14 provided with the thread 12 without play, and into which the thread 12 of the shaft 14 cuts a counterthread.
Here, due to the special design of the sickle tip and due to its eccentric arrangement, the splitting action, which is usually generated by a conventional wood screw during the process of screwing into the wood, should be reduced to a negligible amount. For this purpose, the sickle tip 101 is not only arranged eccentrically, it additionally has the primary cutting edge 30 parallel to or Replacement sheet ( Rule 26)
The secondary cutting edge 70, according to the representation in Figure lb, forms an angle y with the longitudinal axis 80 of the screw 10, which can be up to 40 degrees. The lateral surface 22 of the drilling part 100, according to the representation in Figure 1 c, has a diameter Da which is equal to the core diameter Dk in the embodiment example according to Figure 1. The main free surface 90 is a portion of the lateral surface 22 of the drilling part 100, and thus a cylindrical surface here. The sickle tip 101 is substantially parallel to the longitudinal axis 80 of the screw 10, and at a right angle to the cutting surface 60 it takes up half of the core diameter Dk according to the representation in Figure 1 c, wherein, in the embodiment example according to Figure 1, the cutting surface 60 contains the longitudinal axis 80 of the screw 10.
The screw 10 according to the invention can be manufactured by hot or cold forming and/or machining by cutting a cylindrical starting material or a screw blank.
The type of manufacture is not important for understanding the invention.
In a panel-type workpiece 120 indicated in Figure 8, the above described design of the screw 10 serves the purpose of producing a through hole, which receives the shaft 14 provided with the thread 12 without play, and into which the thread 12 of the shaft 14 cuts a counterthread.
Here, due to the special design of the sickle tip and due to its eccentric arrangement, the splitting action, which is usually generated by a conventional wood screw during the process of screwing into the wood, should be reduced to a negligible amount. For this purpose, the sickle tip 101 is not only arranged eccentrically, it additionally has the primary cutting edge 30 parallel to or Replacement sheet ( Rule 26)
13 substantially parallel to the longitudinal axis 80 of the screw 10, as well as the secondary cutting edge 40 extending obliquely with respect to the longitudinal axis 80 over the width of the drilling part 100. The mode of action of the eccentrically arranged sickle tip 101 and of the main and secondary cutting edges configured on said tip, during the setting of the self-tapping screw, is explained further below in reference to Figure 8.
The embodiment examples according to Figures 2-7 are explained only to the extent that they differ from the first embodiment example according to Figure 1.
Figure 2 or Figures 2a-2d show a second embodiment example of the self-tapping screw according to the invention, wherein a sickle tip 102 is inclined against the longitudinal axis 80 of the screw 10, as one can see in Figures 2c and 2d. In this embodiment example of the screw 10, the cutting surface 60 forms an angle a of up to 30 degrees with the longitudinal axis 80 of the screw. In the representation in Figure 2c, the sickle tip 102 at a right angle to the longitudinal axis 80 takes up half the core diameter Dk. However, in contrast to the embodiment example according to Figure 1, the cutting surface 60 here does not contain the longitudinal axis 80 of the screw.
According to the representation in Figure 2b, the primary cutting edge 30, in an area adjacent to the drilling tip 20, is inclined by a small angle (3 toward the longitudinal axis 80 of the screw against a surface line of the lateral surface 22. The angle (3 can be up to 10 degrees. A
preferred value for the angle (3 is 5 degrees. In general, a small value is chosen for the angle (3, so that the primary cutting edge 30 is still substantially parallel to the longitudinal axis 80. A
preferred value for the angle (3 is therefore 5 degrees. In the embodiment example according to Figure 1, the primary cutting edge 30 could also be inclined by the angle 0 toward the longitudinal axis 80 of the screw 10 against a surface line of the lateral surface 22. Thus, it is not Replacement sheet ( Rule 26)
The embodiment examples according to Figures 2-7 are explained only to the extent that they differ from the first embodiment example according to Figure 1.
Figure 2 or Figures 2a-2d show a second embodiment example of the self-tapping screw according to the invention, wherein a sickle tip 102 is inclined against the longitudinal axis 80 of the screw 10, as one can see in Figures 2c and 2d. In this embodiment example of the screw 10, the cutting surface 60 forms an angle a of up to 30 degrees with the longitudinal axis 80 of the screw. In the representation in Figure 2c, the sickle tip 102 at a right angle to the longitudinal axis 80 takes up half the core diameter Dk. However, in contrast to the embodiment example according to Figure 1, the cutting surface 60 here does not contain the longitudinal axis 80 of the screw.
According to the representation in Figure 2b, the primary cutting edge 30, in an area adjacent to the drilling tip 20, is inclined by a small angle (3 toward the longitudinal axis 80 of the screw against a surface line of the lateral surface 22. The angle (3 can be up to 10 degrees. A
preferred value for the angle (3 is 5 degrees. In general, a small value is chosen for the angle (3, so that the primary cutting edge 30 is still substantially parallel to the longitudinal axis 80. A
preferred value for the angle (3 is therefore 5 degrees. In the embodiment example according to Figure 1, the primary cutting edge 30 could also be inclined by the angle 0 toward the longitudinal axis 80 of the screw 10 against a surface line of the lateral surface 22. Thus, it is not Replacement sheet ( Rule 26)
14 the case that, when using a cutting surface 60 inclined by the angle a, as in Figure 2c, the primary cutting edge 30 also necessarily must have an angle (3, and vice versa. In the embodiment example according to Figure 2, the sickle tip 102 could thus also have the angle a and/or the angle (3, and the same applies accordingly also to the embodiment example according to Figure 1.
Figure 3 or Figures 3a-3d show a third embodiment example of the self-tapping screw 10 according to the invention, wherein a sickle tip 103 is narrower than in the embodiment examples according to Figures 1 and 2. The cutting surface 60 is oriented, in particular in the longitudinal direction of the screw 10 and adjacently to the drilling tip 20, parallel to or substantially parallel to the longitudinal axis 80, as can be seen in Figure 3. Here, the sickle tip 103 at a right angle to the cutting surface 60 takes up less than the core diameter Dk, which can also be seen in Figure 3c. According to Figure 3b, the drilling part 100 has, in an area adjacent to the drilling tip 20, an outer diameter which is shorter by a small distance A
than the core diameter Dk of the shaft 14.
The above explanations pertaining to the use of the angle (3 according to the representation in Figure 2b apply accordingly also to the use of the distance A according to Figure 3b. In the embodiment of the screw 10 according to Figure 3, the drilling part 100 could also have, instead of a reduction by the distance A, the angle 0 at the primary cutting edge 30. In other words, in the embodiments of the screw 10 according to Figures 1 and 2, the primary cutting edge 30 could also be offset by the distance A inward toward the longitudinal axis 80, instead of being inclined by the angle P.
Replacement sheet ( Rule 26)
Figure 3 or Figures 3a-3d show a third embodiment example of the self-tapping screw 10 according to the invention, wherein a sickle tip 103 is narrower than in the embodiment examples according to Figures 1 and 2. The cutting surface 60 is oriented, in particular in the longitudinal direction of the screw 10 and adjacently to the drilling tip 20, parallel to or substantially parallel to the longitudinal axis 80, as can be seen in Figure 3. Here, the sickle tip 103 at a right angle to the cutting surface 60 takes up less than the core diameter Dk, which can also be seen in Figure 3c. According to Figure 3b, the drilling part 100 has, in an area adjacent to the drilling tip 20, an outer diameter which is shorter by a small distance A
than the core diameter Dk of the shaft 14.
The above explanations pertaining to the use of the angle (3 according to the representation in Figure 2b apply accordingly also to the use of the distance A according to Figure 3b. In the embodiment of the screw 10 according to Figure 3, the drilling part 100 could also have, instead of a reduction by the distance A, the angle 0 at the primary cutting edge 30. In other words, in the embodiments of the screw 10 according to Figures 1 and 2, the primary cutting edge 30 could also be offset by the distance A inward toward the longitudinal axis 80, instead of being inclined by the angle P.
Replacement sheet ( Rule 26)
15 In the embodiment according to Figure 3, the cutting surface 60, as in the embodiment according to Figure 2, could also be inclined against the longitudinal axis 80, instead of being parallel to or substantially parallel to the longitudinal axis 80 according to Figure 3c.
Figure 4 or Figures 1-4d show a fourth embodiment of the self-tapping screw 10 according to the invention, wherein a sickle tip 104 is less narrow than in the embodiment example according to Figure 3. The sickle tip 104 at a right angle to the cutting surface 60 takes up more than half the core diameter Dk, as can be seen in Figures 4c. Here, the cutting surface 60 is in the longitudinal direction of the screw and adjacently to the bore tip 20, parallel to or substantially parallel to the longitudinal axis 80 of the screw 10. However, the cutting surface 60 could also be inclined, in the embodiment according to Figure 4, against the longitudinal axis 80 by an angle a as in the embodiment according to Figure 2. The screw 10 in the embodiment according to Figure 4 could also be provided at the primary cutting edge 30 with an angle P as in Figure 2, or a diameter reduced by A compared to the core diameter Dk, as in the embodiment according to Figure 3.
Figure 5 shows a fifth embodiment example of the self-tapping screw 10 according to the invention, in which a sickle tip 105 is inclined against the longitudinal axis 80 of the screw 10, as can be seen in Figures 5b and 5d. Here, the cutting surface 60 is hollowed out inward from a surface line of the drilling part 100, as can be seen in Figure 5b, so that the primary cutting edge 30 is parallel to or substantially parallel to the longitudinal axis 80 of the screw 10 over only a portion of its length, that is to say that it is not configured continuously as a straight line. In the embodiment example according to Figure 5, the lateral surface 22 of the drilling part 100 has a diameter Da which is equal to or substantially equal to the core diameter Dk.
Replacement sheet ( Rule 26)
Figure 4 or Figures 1-4d show a fourth embodiment of the self-tapping screw 10 according to the invention, wherein a sickle tip 104 is less narrow than in the embodiment example according to Figure 3. The sickle tip 104 at a right angle to the cutting surface 60 takes up more than half the core diameter Dk, as can be seen in Figures 4c. Here, the cutting surface 60 is in the longitudinal direction of the screw and adjacently to the bore tip 20, parallel to or substantially parallel to the longitudinal axis 80 of the screw 10. However, the cutting surface 60 could also be inclined, in the embodiment according to Figure 4, against the longitudinal axis 80 by an angle a as in the embodiment according to Figure 2. The screw 10 in the embodiment according to Figure 4 could also be provided at the primary cutting edge 30 with an angle P as in Figure 2, or a diameter reduced by A compared to the core diameter Dk, as in the embodiment according to Figure 3.
Figure 5 shows a fifth embodiment example of the self-tapping screw 10 according to the invention, in which a sickle tip 105 is inclined against the longitudinal axis 80 of the screw 10, as can be seen in Figures 5b and 5d. Here, the cutting surface 60 is hollowed out inward from a surface line of the drilling part 100, as can be seen in Figure 5b, so that the primary cutting edge 30 is parallel to or substantially parallel to the longitudinal axis 80 of the screw 10 over only a portion of its length, that is to say that it is not configured continuously as a straight line. In the embodiment example according to Figure 5, the lateral surface 22 of the drilling part 100 has a diameter Da which is equal to or substantially equal to the core diameter Dk.
Replacement sheet ( Rule 26)
16 Figure 6 or Figures 6a-6d show a sixth embodiment example of the self-tapping screw 10 according to the invention, wherein a sickle tip 106 is configured to be flatter than in the previous embodiment examples. Although the cutting surface 60 contains the longitudinal axis 80 of the screw 10, at a right angle to the cutting surface 60 the sickle tip 106 takes up, however, less than half of the core diameter Dk, as can be seen in Figure 6c. The result is a more shovel-like design of the sickle tip 106.
The cutting surface 60 is oriented in the longitudinal direction of the screw 10 and adjacently to the drilling tip 20, parallel to or substantially parallel to the longitudinal axis 80 of the screw 10. The embodiment of the screw 10 according to Figure 6 could also have the angle 0 according to Figure 2 or the reduction of the diameter by A according to Figure 3.
Figure 7 or Figures 7a-7d show a seventh embodiment example of the self-tapping screw according to the invention, in which a sickle tip 107 is slightly blunted. The primary cutting edge 30 in particular extends in its area directly adjacent to the drilling tip 20 obliquely with respect to the longitudinal axis 80 of the screw 10, and it transitions at a corner 110 into an area in which it extends parallel to or substantially parallel to the longitudinal axis 80 of the screw 10, as can be seen in Figure 7b. The primary cutting edge 30, in its area directly adjacent to the drilling tip 20, is formed by the intersection of the cutting surface 60 and of a bent portion 90' of the main free surface 90. Except for the blunting of the sickle tip 107, the embodiment according to Figure 7 substantially agrees with that of Figure 1, so that the explanations pertaining to Figure 1 also apply to the embodiment according to Figure 7.
All the embodiment examples have in common that at the transition into the shaft 14 of the cutting surface 60, radii, bevels and cavities areas are formed. In addition, in each embodiment example, the thread 12 starts on a portion of the shaft 14, portion which faces the Replacement sheet ( Rule 26)
The cutting surface 60 is oriented in the longitudinal direction of the screw 10 and adjacently to the drilling tip 20, parallel to or substantially parallel to the longitudinal axis 80 of the screw 10. The embodiment of the screw 10 according to Figure 6 could also have the angle 0 according to Figure 2 or the reduction of the diameter by A according to Figure 3.
Figure 7 or Figures 7a-7d show a seventh embodiment example of the self-tapping screw according to the invention, in which a sickle tip 107 is slightly blunted. The primary cutting edge 30 in particular extends in its area directly adjacent to the drilling tip 20 obliquely with respect to the longitudinal axis 80 of the screw 10, and it transitions at a corner 110 into an area in which it extends parallel to or substantially parallel to the longitudinal axis 80 of the screw 10, as can be seen in Figure 7b. The primary cutting edge 30, in its area directly adjacent to the drilling tip 20, is formed by the intersection of the cutting surface 60 and of a bent portion 90' of the main free surface 90. Except for the blunting of the sickle tip 107, the embodiment according to Figure 7 substantially agrees with that of Figure 1, so that the explanations pertaining to Figure 1 also apply to the embodiment according to Figure 7.
All the embodiment examples have in common that at the transition into the shaft 14 of the cutting surface 60, radii, bevels and cavities areas are formed. In addition, in each embodiment example, the thread 12 starts on a portion of the shaft 14, portion which faces the Replacement sheet ( Rule 26)
17 drilling tip 20, and is adjacent to the drilling part 100, as can be seen without problem in the figures.
In reference to Figure 8 or Figures 8a-8e, a drilling process is now described using the example of screw 10 according to the invention corresponding to the embodiment example according to Figure 1. Figures 8a-8d show different phases of the drilling process. Figure 8e shows a detail X on an enlarged scale of the representation according to Figure 8b.
Figure 8a shows the beginning of the drilling process. The self-tapping screw 10 has been set with its sickle tip 101 on the workpiece 120, specifically at a place which corresponds to the center of the cross section of a through bore to be produced in the work piece 120. The longitudinal axis 80 of the screw 10 is inclined by an angle d against a longitudinal axis 85 of the through bore to be produced, as can be seen in Figure 8a. To set the screw 10, any desired screwing tool can be used, which has sufficient play in the receiving portion for the head 11 to allow the inclined arrangement of the screw 10 shown in Figure 8a. The screwing tool needs to turn only around its own axis. The receiving portion of the tool should not perform any type of back and forth movement or a circular movement. Immediately from the start of the drilling process on, the drilling tip 20 moves radially outward in the direction of the periphery of the through bore to be produced. The angle d in the process becomes increasingly smaller, as can be seen in the representation in Figure 8b and in the detail according to Figure 8e. If the workpiece 120 is a workpiece made of wood, the fibers of the wood are severed by the primary cutting edge 30 which moves radially outward. Accordingly, the wood fibers are severed in the axial direction by the secondary cutting edge 40 which moves axially inward. The tendency to move radially outward during the drilling process is conferred to the primary cutting edge 30 by the screw 10 which presses with the inclined secondary cutting edge 40 axially against the workpiece 120.
Replacement sheet ( Rule 26)
In reference to Figure 8 or Figures 8a-8e, a drilling process is now described using the example of screw 10 according to the invention corresponding to the embodiment example according to Figure 1. Figures 8a-8d show different phases of the drilling process. Figure 8e shows a detail X on an enlarged scale of the representation according to Figure 8b.
Figure 8a shows the beginning of the drilling process. The self-tapping screw 10 has been set with its sickle tip 101 on the workpiece 120, specifically at a place which corresponds to the center of the cross section of a through bore to be produced in the work piece 120. The longitudinal axis 80 of the screw 10 is inclined by an angle d against a longitudinal axis 85 of the through bore to be produced, as can be seen in Figure 8a. To set the screw 10, any desired screwing tool can be used, which has sufficient play in the receiving portion for the head 11 to allow the inclined arrangement of the screw 10 shown in Figure 8a. The screwing tool needs to turn only around its own axis. The receiving portion of the tool should not perform any type of back and forth movement or a circular movement. Immediately from the start of the drilling process on, the drilling tip 20 moves radially outward in the direction of the periphery of the through bore to be produced. The angle d in the process becomes increasingly smaller, as can be seen in the representation in Figure 8b and in the detail according to Figure 8e. If the workpiece 120 is a workpiece made of wood, the fibers of the wood are severed by the primary cutting edge 30 which moves radially outward. Accordingly, the wood fibers are severed in the axial direction by the secondary cutting edge 40 which moves axially inward. The tendency to move radially outward during the drilling process is conferred to the primary cutting edge 30 by the screw 10 which presses with the inclined secondary cutting edge 40 axially against the workpiece 120.
Replacement sheet ( Rule 26)
18 This tendency disappears as soon as the screw 10 has moved outward by half of the core diameter Dk. From this time on, the screw 10 drills a hole with the diameter Dk, as can be seen in Figure 8c. Subsequently, the screw 10 with its thread 12 cuts a counterthread into the workpiece 120, as shown in Figure 8d. From this time on, when the primary cutting edge 30 has moved outward by half the core diameter Dk, the angle d between the longitudinal axis 80 of the screw and the longitudinal axis 85 of the bore produced by the screw 10 is equal to zero.
Replacement sheet ( Rule 26)
Replacement sheet ( Rule 26)
19 List of reference numerals Screw 11 Head 12 Thread 14 Shaft Drilling tip 22 Lateral surface Primary cutting edge Secondary cutting edge 60 Cutting surface 70 Auxiliary free surface 80 Longitudinal axis 90 Main free surface 100 Drilling part 101 Sickle tip 102 Sickle tip 103 Sickle tip 104 Sickle tip 105 Sickle tip 106 Sickle tip 107 Sickle tip 110 Corner Replacement sheet (Rule 26)
20 A Distance A' Arrow B' Arrow Dk Core diameter y Angle (3 Angle a Angle Replacement sheet ( Rule 26)
Claims (18)
1. Self-tapping screw (10) with a drilling part (100) and a shaft (14) provided with a thread (12) and a core diameter (D k), wherein the drilling part (100) has a lateral surface (22) and a drilling tip (20) arranged eccentrically in relation to a longitudinal axis (80) of the screw (10), and comprises at least one first cutting edge which extends obliquely with respect to the longitudinal axis (80) of the screw (10), and wherein the drilling part (100) is configured as a sickle tip (101-107), characterized in that the drilling part (100) has a second cutting edge forming a primary cutting edge (30), the second cutting edge being formed substantially by the intersection of a cutting surface (60) and of a main free surface (90), and extends from the drilling tip (20) predominantly parallel to or substantially parallel to the longitudinal axis (80) of the screw (10), in that the first cutting edge is a secondary cutting edge (40) which is formed by the intersection of the cutting surface (60) and of an auxiliary free surface (70), and which extends from the drilling tip (20) obliquely with respect to the longitudinal axis (80) of the screw (10) over the width of the drilling part (100), and in that the drilling tip (20) lies on an imaginary circle around the longitudinal axis (80) of the screw (10), whose diameter is equal to or substantially equal to the core diameter (D k).
2. Self-tapping screw according to claim 1, characterized in that the drilling tip (20) is formed by the intersection of the cutting surface (60), of the auxiliary free surface (70), and of the main free surface (90).
3. Self-tapping screw according to claim 1 or 2, characterized in that the secondary cutting edge (40) forms an angle (y) of up to 40 degrees with the longitudinal axis (80) of the screw (10).
4. Self-tapping screw according to any one of claims 1 to 3, characterized in that the lateral surface (22) of the drilling part (100) has a diameter (D
a) which is equal to or substantially equal to the core diameter (D k).
a) which is equal to or substantially equal to the core diameter (D k).
5. Self-tapping screw according to any one of claims 1 to 4, characterized in that the main free surface (90) is a portion of the lateral surface (22) of the drilling part (100).
6. Self-tapping screw according to any one of claims 1 to 5, characterized in that the sickle tip (101-107) is substantially parallel to the longitudinal axis (80) of the screw (10).
7. Self-tapping screw according to claim 6, characterized in that the sickle tip (102, 102, 105, 107) at a right angle to the cutting surface (60) takes up half the core diameter (D k).
8. Self-tapping screw according to any one of claims 1 to 7, characterized in that the cutting surface (60) contains the longitudinal axis (80) of the screw (10).
9. Self-tapping screw according to any one of claims 1 to 7, characterized in that the cutting surface (60) forms an angle (.alpha.) of up to 30 degrees with the longitudinal axis (80) of the screw (10).
10. Self-tapping screw according to claim 9, characterized in that the primary cutting edge (30) in an area adjacent to the drilling tip (20) is inclined by a small angle (.beta.) of up to 10 degrees toward the longitudinal axis (80) of the screw (10) against a surface line of the lateral surface (22).
11. Self-tapping screw according to any one of claims 1 to 6, characterized in that the cutting surface (60) is oriented in the longitudinal direction of the screw (10) and adjacently to the drilling tip (20), parallel to or substantially parallel to the longitudinal axis (80) of the screw (10).
12. Self-tapping screw according to any one of claims 1 to 6, characterized in that the sickle tip (103, 106) at a right angle to the cutting surface (60) takes up less than half the core diameter (D k).
13. Self-tapping screw according to claim 12, characterized in that the drilling part (100) in an area adjacent to the drilling tip (20) has an outer diameter which is smaller by a small distance (A) than the core diameter (D k) of the shaft (14).
14. Self-tapping screw according to any one of claims 11 to 13, characterized in that the sickle tip (104) at a right angle to the cutting surface (60) takes up more than half the core diameter (D k).
15. Self-tapping screw according to any one of claims 1 to 8, characterized in that the cutting surface (60) is hollowed out inward from a surface line of the drilling part (100), so that the primary cutting edge (30) is parallel to or substantially parallel to the longitudinal axis (80) of the screw (10) over only a portion of its length.
16. Self-tapping screw according to any one of claims 1 to 8, characterized in that the primary cutting edge (30) extends, in its area directly adjacent to the drilling tip (20), obliquely with respect to the longitudinal axis (80) of the screw (10) and transitions at a corner (110) into an area in which it extends parallel to or substantially parallel to the longitudinal axis (80) of the screw (10).
17. Self-tapping screw according to any one of claims 1 to 16, characterized in that at the transition into the shaft (14) on the cutting surface (60), radii, bevels or cavities are formed.
18. Self-tapping screw according to any one of the claims 1 to 17, characterized in that the thread (12) starts on a portion of the shaft (14) facing the drilling tip (20) and adjacent to the drilling part (100).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102010017267A DE102010017267B3 (en) | 2010-06-07 | 2010-06-07 | Self-drilling screw |
| DE102010017267.7 | 2010-06-07 | ||
| PCT/EP2011/058886 WO2011154279A1 (en) | 2010-06-07 | 2011-05-31 | Self-tapping screw |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2793494A1 CA2793494A1 (en) | 2011-12-15 |
| CA2793494C true CA2793494C (en) | 2018-03-06 |
Family
ID=44119356
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2793494A Active CA2793494C (en) | 2010-06-07 | 2011-05-31 | Self-tapping screw |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP2577074B1 (en) |
| CA (1) | CA2793494C (en) |
| DE (1) | DE102010017267B3 (en) |
| PL (1) | PL2577074T3 (en) |
| WO (1) | WO2011154279A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2752588A1 (en) * | 2013-01-02 | 2014-07-09 | Shu-Chin Huang | Flat drill end of a screw |
| AU2013200163B2 (en) * | 2013-01-14 | 2016-03-17 | Shu-Chin Huang | Flat drill end of a screw |
| DE102017208282A1 (en) * | 2017-05-17 | 2018-11-22 | Schmid Schrauben Hainfeld Gmbh | Wood screw made of metal for structural timber construction and method for producing a wood screw |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH50995A (en) * | 1910-01-13 | 1911-07-17 | August Mueller Carl | Wood screw |
| DE2913482A1 (en) * | 1979-04-04 | 1980-10-16 | Frank Knoche | Self-drilling screw design - has non-round tip offset from centre line of shank |
| US4477217A (en) * | 1981-06-01 | 1984-10-16 | Rockford Products Corporation | Drill and thread forming screw |
| US4568229A (en) * | 1983-05-09 | 1986-02-04 | Construction Fasteners, Inc. | Drill tip and fastener employing same |
| DE10147767B4 (en) * | 2001-09-27 | 2005-09-15 | Sfs Intec Holding Ag | Self-drilling screw |
| DE202007018179U1 (en) * | 2007-12-18 | 2008-03-13 | Reisser Schraubentechnik Gmbh | screw |
-
2010
- 2010-06-07 DE DE102010017267A patent/DE102010017267B3/en not_active Expired - Fee Related
-
2011
- 2011-05-31 PL PL11722086T patent/PL2577074T3/en unknown
- 2011-05-31 WO PCT/EP2011/058886 patent/WO2011154279A1/en active Application Filing
- 2011-05-31 CA CA2793494A patent/CA2793494C/en active Active
- 2011-05-31 EP EP11722086.3A patent/EP2577074B1/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| EP2577074A1 (en) | 2013-04-10 |
| EP2577074B1 (en) | 2016-01-20 |
| WO2011154279A1 (en) | 2011-12-15 |
| PL2577074T3 (en) | 2016-06-30 |
| DE102010017267B3 (en) | 2011-12-15 |
| CA2793494A1 (en) | 2011-12-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request |
Effective date: 20151201 |