Patent Description:
The present disclosure is directed to a system for mechanical die-based manufacture of threaded fasteners.

Thread rolling to manufacture bolts, screws, and other threaded fasteners requires rapid rolling of fastener blanks between a mobile die and a stationary die to form the thread. The manufacturing apparatus reciprocates the mobile die back and forth relative to the stationary die at a high rate of speed, often hundreds of reciprocations in a minute. Because many different blank and thread configurations may be used with and required from one manufacturing apparatus, numerous different dies can be interchangeably used with the same machine. While switching out dies may change the thread patterns, accommodating the different size and shape of the blanks usually falls to the die holders of the apparatus. Such holders typically include an adjustment mechanism which can alter the location and angulation of the dies to accommodate different blanks.

All current manufacturing equipment requires adjustment to the pressure and distance between the faces of the dies, and occasionally the angulation of one or both of the dies. The industry's standard practice uses a threaded adjustment to properly position the die faces. Operators may require several years of training to learn the appropriate "feel" required for current adjustment methods to produce good fasteners, often resulting in unusable batches of product during the long training period. Furthermore, such adjustment mechanisms can be shifted out of position accidentally or over the course of production. Moreover, due to the rapid reciprocating movement of the mobile die and its respective mobile die holder, as well as the cantilevered positioning of the mobile die holder on the apparatus, the mobile die holder may be subject to forces which move it out of alignment, creating further waste of time and material.

It is therefore the object of this application to provide a die positioning system which provides accurate, easily reproducible positioning of at least one die and its corresponding die holder over long periods of high use.

<CIT>) describes cold-forming equipment configured as a high precision thread rolling assembly utilizing racks, guide rails, a bearing assembly including rolling element linear motion bearings and a gear reduction assembly. The thread rolling assembly includes a pair of stationary button blocks between a stationary die block and a stationary die, with recipe blocks and a pair of moving button blocks between a moving die block and a moving die. Each of the stationary and moving button blocks includes a pair of apertures configured to receive a die button.

One aspect of the present invention is a die positioning system as defined by claim <NUM>.

Another preferred aspect of the present invention is a die positioning system including multiple pairs of key bars, at least one pair of key disc inserts, multiple sets of key discs, and at least one set of disc backers according to the system shown above.

It should be understood that for clarity, not every part is labeled in every drawing. Lack of labeling should not be interpreted as a lack of disclosure.

<FIG> and <FIG> present perspective views of one embodiment of key system <NUM> for use in a die positioning system <NUM>. Each key system <NUM> includes a plurality of pairs of key bars <NUM>, a plurality of sets of key discs <NUM>, and at least one pair of key disc inserts <NUM>. In the exemplary embodiment of <FIG>, system <NUM> includes <NUM> pairs of key bars <NUM>, <NUM> sets of key discs <NUM>, and one pair of key disc inserts <NUM>. Other embodiments may include more or fewer pairs of key bars <NUM>, sets of key discs <NUM>, and pairs of key disc inserts <NUM>.

Each key bar <NUM> of each pair of key bars <NUM> is a solid rectangular cuboid having an identical thickness within the pair, but differing from the thickness of other pairs of key bars <NUM> in the key system <NUM>. Pairs of key bars <NUM> typically differ in thickness at increments of approximately <NUM> (<NUM> inches), though other increments are possible. Each pair of key bars <NUM> may be uniquely marked within the key system <NUM> by alphanumeric and/or colored indicia for identification and separation from other pairs of key bars <NUM>.

Each key disc <NUM> of each set of key discs <NUM> is a solid three-dimensional shape having an identical thickness within the set, but differing from the thickness of other sets of key discs <NUM> in the key system <NUM>. While the key discs <NUM> shown in the instant figures are cylindrical, other three-dimensional shapes, such as cuboids, cubes, hemispheres, prisms, and/or any combination thereof, are contemplated and encompassed by the claims of this application. Sets of key discs <NUM> typically include four key discs <NUM>, though other embodiments may use more or fewer key discs <NUM>. Sets of key discs <NUM> typically differ in thickness at increments of approximately <NUM> (<NUM> inches), though other intervals are possible. Each set of key discs <NUM> may be uniquely marked within the key system <NUM> by alphanumeric and/or colored indicia for identification and separation from other sets of key discs <NUM>. Sets of key discs <NUM> may be used completely or may be "mixed and matched" with key discs from another set to angle a stationary die D or a mobile die D.

Each key disc insert <NUM> includes at least one disc aperture <NUM> designed to receive and hold a single key disc <NUM>. The key aperture <NUM> has a diameter greater than the key disc <NUM>, and a shape conforming to the outer periphery of the key disc <NUM>. In the exemplary embodiment of <FIG> and <FIG>, each key disc insert <NUM> includes two disc apertures <NUM>, though other embodiments may use more or fewer key disc apertures <NUM>. Each key disc insert <NUM> has a stepped configuration between a thicker section and a thinner section. The thinner section is equal in thickness to or thinner than the thinnest set of key discs <NUM> to allow proper biasing using each set of key discs <NUM> in the key system <NUM>. The thicker section extends above the die holder H with the step holding the key disc insert <NUM> in place vertically with respect to the die D and the die holder H. In certain embodiments, at least one magnet aperture <NUM> extends through a sidewall of each disc aperture <NUM> to accommodate at least one capture magnet <NUM>. The capture magnet <NUM> helps to hold the key disc <NUM> in place in the disc aperture <NUM>, as the key discs <NUM> can be made from a ferromagnetic or ferrimagnetic material.

In use, as can be seen in <FIG> and <FIG>, at least one recess within the die holder H receives a pair of key bars <NUM> and a pair of key disc inserts <NUM> in the space between the die D and the die holder H. The key disc inserts <NUM> hold at least one set of key discs <NUM>. One key bar <NUM> of the pair of key bars <NUM> and one key disc insert <NUM> of the pair of key disc inserts <NUM> extends along a first end of one side of the die D, while the other key bar <NUM> of the pair of key bars <NUM> and the other key disc insert <NUM> of the pair of key disc inserts <NUM> extends along a second end of the same side of the die D, as can be seen in <FIG>. In the embodiment of <FIG>, the position of the die D can thereby be adjusted in increments of approximately <NUM> (<NUM> inches) by changing the key bars <NUM> used, and adjusted in increments of approximately <NUM> (<NUM> inches) by changing the key discs <NUM> used.

If a user wishes to create a vertical or horizontal angle for the surface of the die D, they may combine the key discs <NUM> from different sets. For vertical angulation, the thicker key discs <NUM> are typically placed in lower disc apertures <NUM>, though reversal is possible. By way of non-limiting example, if a first set of key discs <NUM> has a thickness of approximately <NUM> (<NUM> inches) and a second set of key discs <NUM> has a thickness of approximately <NUM> (<NUM> inches) with a distance between center points of the disc apertures <NUM> of approximately <NUM> (<NUM> inches), the surface of the die D will have an angulation of approximately <NUM> degrees from vertical if using the thinner key discs <NUM> in the upper disc apertures <NUM>. It is contemplated that the key discs <NUM> from any number of different sets of key discs <NUM> may be used to create vertical and/or horizontal angulation of the die D, depending upon the desired angulation and number of the key discs <NUM> which can be used within the die positioning system <NUM>.

Each key system <NUM> can be used with either a stationary or a mobile die D. Because most manufacturing apparatuses include both stationary and mobile dies D, two key systems <NUM> may be used, one for each die D. Referring back the above example, doubling the angulation, that is, providing similarly differentiated key discs <NUM> in the key disc inserts <NUM> for both the mobile and stationary dies D, will result in a fastener having a taper of approximately <NUM> degrees.

As shown in <FIG>, a disc adjustment assembly <NUM> allows the key system <NUM> to be stabilized at any angle. Within the assembly <NUM>, sets of disc backers <NUM> interact with sets of key discs <NUM> to allow the key discs <NUM> to extend at an angle relative to the plane of the die holder H. While the embodiment shown in <FIG> includes four disc backers <NUM>, sets with more and fewer disc backers <NUM> are contemplated to interact with the same number of key discs <NUM>.

The disc backers <NUM> have backer surfaces <NUM>, non-planar forward surfaces which are placed behind the key discs <NUM>. In the embodiment shown in <FIG> and <FIG>, the backer surfaces <NUM> at the front of disc backers <NUM> have a domed, convex configuration allowing at least partial rotation of the key discs <NUM> about at least three axes. In other embodiments, the backer surfaces <NUM> have a spherical or at least partially spherical convex configuration with complementary concave mating surfaces on the backs of the key discs <NUM>, also allowing at least partial rotation of the key discs <NUM> about at least three axes. The reverse may also be true, with the backer surfaces <NUM> having a spherical or at least partially spherical concave configuration with complementary convex mating surfaces on the backs of the key discs <NUM>. In certain other embodiments, the backer surfaces <NUM> have a convex angled configuration, allowing at least partial rotation of the key discs <NUM> about two axes. All of these configurations prevent the disc backers <NUM> from exerting a force on an edge of the key discs <NUM>, preventing deformation of the key discs <NUM>.

<FIG> and <FIG> also present perspective and partial cross-sectional views, respectively, of one embodiment of a die clamp assembly <NUM> for use in the die positioning system <NUM>. In the clamp assembly <NUM>, a clamp top <NUM> removably secures the die D to a clamp base <NUM>. A backplate <NUM> extending between the clamp top <NUM> and the clamp base <NUM> includes at least two lateral back flanges <NUM> to either side. Each back flange <NUM> includes at least one backer aperture <NUM> aligned with a disc aperture <NUM> on the key disc inserts <NUM>. The disc backers <NUM> extend at least partially through each backer aperture <NUM>. When the key discs <NUM> are used in system <NUM>, the backer surface <NUM> at the forward surface of each disc backer <NUM> contacts a back surface of the key disc <NUM>, allowing the key disc <NUM> to have an adjustable angle with respected to the vertical backplate <NUM>, resulting in a better-supported angulation of the key bars <NUM>.

A raised base surface <NUM> on the upper surface of the clamp base <NUM> also enables additional stability in clamping the die D by allowing angulation for the die D between the clamp top <NUM> and the clamp base <NUM>. Because the raised base surface <NUM> extends parallel to yet set back from the forward edge of the clamp base <NUM>, the die D may be angled inwardly or outwardly. The raised base surface <NUM> extends behind a first clamp base surface 137a and in front of a second clamp base surface 137b. Because both clamp base surfaces 137a and 137b are lower than the raised base surface <NUM>, the die D may be angled with either a forward or backward slope, depending on the arrangement of the key discs <NUM>.

Clamping the die D securely when using the key bars <NUM> and the key discs <NUM> requires special geometry so the system <NUM> works at any angle created by having a different key disc <NUM> and/or key bar <NUM> in the system <NUM> creating a taper. A difference in the diameter at the top and bottom of the part being rolled or special geometry require distance adjustments between the top and bottom of the die D. The disc backers <NUM> have a fixed distance apart; knowing this distance allows the calculation of the correct combination of key discs <NUM> and/or key bars <NUM> for each part. The backer surface <NUM> on the front of each disc backer <NUM> allows the key discs <NUM> to incline and align more effectively with the key bars <NUM> and the die D.

The raised central geometry of the raised base surface <NUM> on the clamp base <NUM> enables the die D to be clamped down securely. If the upper surface of clamp base <NUM> was flat, the die D would have tendency to straighten when clamped by the clamp top <NUM>. Clearance is required on the left and right of this surface. Because the angle produced by the key discs <NUM> of differing thickness may be positive or negative, the raised base surface <NUM> is raised in the center, as seen in <FIG>. The central rise allows the die D to slope inwardly from the top or outwardly from the top, depending on whether the top or bottom key disc <NUM> is thickest, respectively.

<FIG> presents a perspective view of another embodiment of the disc adjustment assembly <NUM> for use with the key system <NUM>. This embodiment of the disc adjustment assembly <NUM> includes the previously-discussed disc backers <NUM>, and adds a plurality of datum spacers <NUM> and a plurality of draw bolts <NUM>. Each datum spacer <NUM> receives at least part of a disc backer <NUM> at one end and receives at least part of the threaded draw bolt <NUM> through its opposite, threaded end.

<FIG> presents a cross-sectional view of the above embodiment of disc adjustment assembly <NUM> in use. In use, this embodiment of the assembly <NUM> is not placed between the die D and the die holder H, but between a key base K and the die holder H. As a result, the entire die holder H is angled and/or offset instead of just the die D. The die holder H is supported by a die holder rest Hr, which allows proper angulation of the die holder H, similarly to the way in which the raised base surface <NUM> allows angulation of the die D in <FIG>. While the die holder rest Hr has a circular cross-section in the embodiment of <FIG>, other cross-sectional configurations allowing angulation of the die holder H are contemplated.

Each datum spacer <NUM> in located in a stepped bore within the key base K. The draw bolt <NUM> extends from the back of the key base K through the narrower section of the bore and into the datum spacer <NUM> to hold the datum spacer <NUM> in place within the key base K. The datum spacer <NUM> is located in the wider section of the bore, along with the disc backer <NUM>. Part of the disc backer <NUM> extends into the datum spacer <NUM> to hold the disc backer <NUM> in place within the key base K. In the embodiment of <FIG>, four datum spacers <NUM> are used; other embodiments may have more or fewer datum spacers <NUM>. The datum spacers <NUM> extend parallel to each other; their longitudinal axes are parallel in XY and YZ planes.

The various embodiments of the key system <NUM> and the disc adjustment assembly <NUM> may be retrofit onto/into existing dies D and manufacturing devices. The combination of alphanumeric and/or colored indicia from the pair(s) of key bars <NUM> and the set(s) of key disc inserts <NUM> which are used with a particular die and/or manufacturing apparatus to create a particular type of fastener may be recorded and provided in a standardized listing of combinations. In certain embodiments, one of the key bars <NUM> and the key disc inserts <NUM> may have alphabetical indicia and the other of the key bars <NUM> and the key disc inserts <NUM> may have numerical indicia to facilitate easier identification. In certain embodiments, the type of fastener to be manufactured may be entered into a computer program, along with the die(s) and/or manufacturing apparatus to be used. Software algorithms may use the information to retrieve a known combination or extrapolate potential combinations from known combinations.

<FIG>, <FIG>, and <FIG> show perspective, cross-sectional, and exploded views, respectively, of a bearing assembly <NUM> which may be used in the system <NUM> in conjunction with, or separately from the key system <NUM> and the disc adjustment assembly <NUM>. Whether using a linear bearing or other bearing means for manufacturing threaded fasteners, it is critical that the apparatus does not oscillate vertically (up or down along the vertical axis of the fasteners, as can be seen in <FIG>, represented by dashed lines). All fastener blanks, especially metric or English machine fastener blanks, must have a consistent helix angle. If the helix angle varies at all, the performance of the fastener is hampered. In the art, this is called a drunken thread. Making this more complicated is the fact that all bearings, including linear bearings, require clearance (also known as play) to operate, which may result in unwanted oscillation in a direction orthogonal to the direction of motion. In certain embodiments of the die positioning system <NUM>, a bearing assembly <NUM> can be added directly to a linear bearing assembly A with a reciprocating mobile die holder H to prevent this from happening. When using a linear bearing and a rack and pinion system this additional stability is a requirement to prevent a drunken thread.

As shown in <FIG>, <FIG>, and <FIG>, the linear bearing assembly A includes three elements to make up a working assembly A. A base slide B is connected directly to the machine base and is stationary. The base slide B includes a stationary bearing rail Rs. In the case of a linear bearing assembly <NUM>, a center subassembly C contains two sets of linear bearings L1 and L2 opposing each other. The center subassembly C is positionally controlled by a pinon gear P that interacts with the base slide B and a moving slide M. The moving slide M contains an additional moving bearing rail Rm.

At least one bearing assembly <NUM> is used in the linear bearing assembly A to prevent oscillation. Each bearing assembly <NUM> also includes at least three elements. A plurality of roller bearings <NUM> are directly attached to the base slide B or the machine base. While the embodiment shown in <FIG> includes at least two roller bearings 141a and 141b, other embodiments may include more roller bearings <NUM>. At least one slide rail <NUM> is directly attached to mobile slide M. When the base slide B, the center subassembly C, and the moving slide M are in normal operation, the roller bearings 141a and 141b directly support the moving slide M via the slide rail <NUM>, preventing the moving slide M from experiencing any vertical oscillation. Because the roller bearings <NUM> can operate at normal manufacturing rates and pressures exerted during thread forming operations, the roller bearings <NUM> will not affect manufacturing speed for the linear bearing assembly A.

The roller bearings <NUM> and the slide rail <NUM> may be retrofit onto existing linear bearing assemblies A. The roller bearings <NUM> have diameters smaller than the inner diameter of the slide rail <NUM>. In various embodiments, the roller bearings <NUM> can include caged ball bearings, cylindrical roller bearings, spherical roller bearings, and/or tapered roller bearings. In certain embodiments, the roller bearings <NUM> are vertically offset from each other to provide specific support along the upper inner surface of the slide rail <NUM> and the lower inner surface of the slide rail <NUM>, respectively.

Claim 1:
A die positioning system for positioning a die of a system for mechanical die-based manufacture of threaded fasteners, comprising:
a pair of key bars, each key bar (<NUM>) of the pair of key bars having a solid rectangular cuboid configuration identical in thickness to the other key bar of the pair of key bars;
a pair of key disc inserts (<NUM>), each key disc insert having at least one disc aperture (<NUM>) extending therethrough;
a set of key discs, each key disc (<NUM>) of the set of key discs having a solid three dimensional configuration identical in thickness to all other key discs of the set of key discs, each key disc having a diameter equal to or less than a diameter of the at least one disc aperture (<NUM>) and each key disc having a thickness equal to or greater than a thickness of a section of the key disc insert that the at least one disc aperture extends through; and
a set of disc backers (<NUM>), wherein a forward surface (<NUM>) of each disc backer comprises a backer surface having a non-planar configuration, said forward surface for placing behind a key disc (<NUM>).