Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Pilot end having means enhancing fastening or installation
Reexamination Certificate
2000-01-24
2002-10-22
Saether, Flemming (Department: 3679)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Pilot end having means enhancing fastening or installation
Reexamination Certificate
active
06468013
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a threaded bolt.
BACKGROUND OF THE INVENTION
A threaded bolt is known from U.S. Pat. No. 4,952,110. This threaded bolt is provided with an eccentric tip with a smooth portion and a threaded portion, located opposite each other. The threaded portion of the eccentric tip is located on the surfaces that are substantially aligned with the threaded surfaces of the shank of the threaded bolt. The smooth surfaces are located at the areas of the tip that are radially inwardly shifted with respect to the threaded surfaces of the shank.
In the known threaded bolt, the eccentric arrangement of the tip also provides a means for axial alignment of the central axis of the threaded bolt and the central axis of the nut or tapped hole. The threaded side of the tip helps to prevent an inclined position (“cross-threads”) of the threaded bolt.
Cross-threading occurs when a threaded bolt, especially in the automobile industry, does not precisely, or with a deviation of more than 5° with respect to the perpendicular direction of insertion, fit in a nut or tapped hole. Such a form of cross-threading is also called angular deviation.
From U.S. Pat. No. 4.981.406 a threaded bolt is known with a threaded shank and a tip that may be threaded on one side and may be smooth on the other side, possibly with inwardly shifted areas, and the central axis of which is at an angle with or parallel, yet staggered, to the central axis of the shank.
From the European patent application 0.475.712 a threaded bolt is known with a threaded shank and with a tip, the surface of which, on one side, forms a continuation of the thread of the shank and, on the other side, is smooth and is tapered in distal direction.
All the cited, known threaded bolts have the disadvantage that, although they provide a certain degree of alignment, the threaded portion on the tip results in a destruction of the thread of the nut or tapped hole when the insertion position of the threaded bolt is too oblique. It has to be kept in mind here that, especially in the automobile industry, robots are used to screw the threaded bolts in the appropriate holes with a predetermined turning moment. This means that, independent of the situation the threaded bolt that is to be screwed in encounters, the threaded bolt is rotated in until the required tightening moment, which, if the thread has an incorrect position with respect to the screw hole, may result in an unacceptable degree of deformation of either of the threads when they interact. The connection in question will then not be as it should be, as a result of which, after this has been ascertained, the connection will either have to be repaired, causing loss of time, or a certain degree of danger will have been created for the period during which the end product, particularly a motor-car, is used.
Other known threaded bolts have a tip that is provided with a circumferential thread that forms a continuation of the thread of the shank, yet wherein the tip is centrically tapered. Such threaded bolts are not given preference because a tip like that is difficult to manufacture, while, in addition, the effect with respect to the realization of the alignment of the central axis of nut or tapped hole and threaded bolt is very limited.
Another known threaded bolt has a threaded shank that is provided with a truncated conically shaped, centric, smooth head, in which a circular cylinder portion is provided between the smooth head and the shank, which circular cylinder portion is also smooth and has a diameter that is smaller than the inner diameter of the thread on the shank. The aligning function of this bolt, too, leaves much to be desired.
Another, similar threaded bolt has a truncated conically shaped, centric, smooth head with a convex generatrix and, in proximal direction, connecting smooth, circular cylinder-shaped surfaces, the diameter of which substantially corresponds to the inner diameter of the threaded shank.
In the automotive industry, in particular, it is becoming more and more difficult to attune the parts that have to be assembled in such a way that they precisely coincide at their several points of attachment. It may occur that certain parts have to be fastened to one another at as many as five or six places with the aid of threaded bolt connections. If the high cost involved with accurate attuning, and, consequently, a minimizing of the tolerances, is to be avoided, measures will have to be taken with which deviations can be levelled out. Nowadays, for this purpose case nuts (floating nuts) are used that are located on a plate member that has to be fastened, with their screw hole behind the relatively large hole of that one plate that has to be fastened. In accordance with the dimensions of the slotted hole, said case nuts have a freedom of movement that is limited by retainers welded to that one plate that has to be fastened. Owing to the necessary freedom of position of said case nuts, these will often not be in alignment with the fastening holes of the other part/plate that has to be fastened.
An improved threaded bolt is disclosed in European patent 0.832.363 in the name of assignee. This known threaded bolt provides a solution to many of the above-mentioned problems.
U.S. Pat. No. 5.073.073 discloses a threaded bolt having a smooth distal end comprising a right-circular cylindrical distal portion located offset with respect to the shank central axis and a truncated portion located between said distal portion and the threaded shank.
It is also known to provide a threaded bolt with measurement planes by arranging measurement planes at a recess or an elevation with respect to the actual end planes at both the head end and at the insertion end by means of cold deformation. The presence of several radial planes, situated at different axial distances measured along the centre line of the threaded bolt, however, has a detrimental influence on the recognizability and the clearness of the measurement results. This threaded bolt is described in European patent application 0.459.365, the contents of which should be considered inserted here by reference.
Another proposal is known from U.S. Pat. No. 4.846.001, in which a threaded bolt is shown of which the head is provided with a recess with a measurement plane in it, which by finishing has been made sufficiently smooth/level, in order to be used in ultrasonic measuring. The recess is used for accommodating a piezo-electric sensor. In another embodiment the recess is absent and the sensor is placed at the end plane at the head.
There is still a need, however, for a further improved threaded bolt with which, even under the above circumstances, alignment can be guaranteed, and cross-threading is prevented in addition, and which therefore has a practically maximum capacity to align the central axes of holes and threaded bolt, as well as an improved optimal capacity for correcting oblique positions of insertion of the threaded bolt.
SUMMARY OF THE INVENTION
For this purpose, the invention provides a threaded bolt having a distal insertion end and a proximal head-end and a threaded shank extending in between, said shank having a longitudinal axis, wherein the distal insertion end comprises a first distal portion that comprises the outermost distal end of the distal insertion end, said outermost distal end being eccentrically located with respect to the central axis of the shank, the first distal portion defining a circumferentially continuous, smooth, non-threaded surface, in which a second distal portion, in proximal direction, connects to said first distal portion, said second distal portion defining a circumferentially continuous, smooth, non-threaded, right-circular cylindrical surface, which is located centrically with respect to the central axis of the shank, wherein the first distal portion has been provided with surfaces, the generatrix of which has a straight course and is inclined with respect to the longitudinal axis.
Preferably, said surfaces of said first distal portion form part of a conical s
Koninklijke Nedschoref Holding N.V.
Saether Flemming
Thomas Kayden Horstemeyer & Risley LLP
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