US3195156A - Method of producing thread swaging devices - Google Patents

Method of producing thread swaging devices Download PDF

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Publication number
US3195156A
US3195156A US115846A US11584661A US3195156A US 3195156 A US3195156 A US 3195156A US 115846 A US115846 A US 115846A US 11584661 A US11584661 A US 11584661A US 3195156 A US3195156 A US 3195156A
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Prior art keywords
thread
blank
shank
screw
pitch
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US115846A
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English (en)
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Jr Harvey F Phipard
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Research Engineering and Manufacturing Inc
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Research Engineering and Manufacturing Inc
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Priority to US115846A priority Critical patent/US3195156A/en
Priority to DE1961R0031282 priority patent/DE1400229C2/de
Priority to SE10341/61A priority patent/SE341295B/xx
Priority to AT793261A priority patent/AT242447B/de
Priority to BE609563A priority patent/BE609563R/fr
Priority to CH1247861A priority patent/CH386182A/fr
Priority to DK427361AA priority patent/DK134413B/da
Priority to NO141974A priority patent/NO115459B/no
Priority to ES271676A priority patent/ES271676A1/es
Priority to FR877628A priority patent/FR81507E/fr
Application granted granted Critical
Publication of US3195156A publication Critical patent/US3195156A/en
Priority to US590699A priority patent/US3918345A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
    • F16B25/0078—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw with a shaft of non-circular cross-section or other special geometric features of the shaft
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
    • B21H3/00—Making helical bodies or bodies having parts of helical shape
    • B21H3/02—Making helical bodies or bodies having parts of helical shape external screw-threads ; Making dies for thread rolling
    • B21H3/027—Rolling of self-tapping screws
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/001—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed
    • F16B25/0021—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed the material being metal, e.g. sheet-metal or aluminium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
    • F16B25/0036—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw
    • F16B25/0042—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw
    • F16B25/0047—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by geometric details of the screw characterised by the geometry of the thread, the thread being a ridge wrapped around the shaft of the screw the ridge being characterised by its cross-section in the plane of the shaft axis

Definitions

  • the present invention relates to vices, particularly to self-tapping screws and the like devices, and to factoring the same.
  • Self-tapping screws fall into two broad classes, the first being those which are provided with cutting edges at the work-entering end, the second, and most common, being those which are so designed as to form threads with a swaging operation. Screws of the first type have numerous disadvantages, one of the most significant being that they all form chips which are cut from the body into which they are driven. While screws of the second type form no chips, they have other equally serious limitations. Depending upon the nature and hardness of the metal into which they are driven, screws of the second type require a high driving torque, particularly in metal greater than one-eighth inch in thickness. High driving torque is objectionable, not only as regards manual drivability, but also in connection with the use of clutch controlled power driver-s such as are used in assembly lines.
  • the driver clutch must be so set that the screws will consistently be driven home to the fully seated position before disengagement.
  • the driving torque of individual screws varies considerably due to presence of any lubricant, surface condition of the threads, and other variable factors.
  • the stripping torque of the mating threads as well as the failure torque of the screws vary considerably from one to the next.
  • clutch mechanisms of the power drivers cannot be relied upon to disengage at precisel the same torque value each time. Therefore, if the differential between the average value of the driving torque of a quantity of screws and the average value of the failure torque is relatively narrow, it will be extremely difficult to adjust the clutch so that the driver will be disengaged properly each time. When this does not occur, the threads will be stripped, or the screw will be broken, either of which will result in costly delays of the assembly line while repair or replacement is made.
  • a further object of the invention is to provide a new and improved thread-forming screw having a relatively low driving torque and a relatively high stripping or failure torque so that the difierential between such torques is relatively great, making it easier for the adjustment of thread-forming deor thread-forming methods for manu- 3,i5,l5h Patented July 20, 1%65 ice automatic clutches of power drivers so that clutch disengagement can more readily be eflected prior to failure of the screw or stripping of the threads of the parent body.
  • a still further object of the present invention is to provide a new and improved self-threading device whereby substantially full threads may be formed with a substantiaiiy perfect fit thereby resulting in a more perfect assembly due to the snug fit between the screw and the parent body.
  • a still further object of the present invention is to provide a new and improved self-threading device which may be driven into metal of any thickness, such as, into blind holes.
  • the thread-forming device of arcuate polygonal cross-sectional shape having an odd number of sides. While others have heretofore proposed thread-forming devices of various different noncircular cross-sectional shapes, those have been of such a complicated nature as to render them entirely unsuitable for production on a commercial basis, or else the cost of manufacture was so great as to restrict the field of use within very narrow limits. In most instances, however, such non-circular, or lobular, cross-sectional shapes as have been proposed heretofore were accompanied by one or more serious defects, either in details of configuration or in the methods required for manufacturing the same, so as substantially to preclude their successful manufacture and usage. The particular noncircular, or lobular shapes herein disclosed as being of my invention, are such as enables the manufacture of the thread-forming devices on mass production basis with machinery readily available .while the resultant product possesses the superior performance characteristics recited above.
  • Another object of the invention is to provide a new and improved method of making a lobular thread-forming device, which method resides in forming a blank having a work-entering end portion, shaping at least such portion into an arcuate lobular configuration having an odd number of arcuate sides with each transverse cross section of substantially equal width throughout 360 degrees, and then rolling a continuous thread on the blank including the end portion, and while doing so, maintaining on at least the end portion an arcuate lobular pitch surface configuration that in every transverse cross section is of equal width throughout 360 degrees, and during the rolling operation forming a taper on the crest of the thread on the end portion, which taper extends inwardly toward the tip thereof.
  • FIG. 1 is a side view of a thread-forming member according to one form of the present invention
  • FIG. 2 is an end view of the member shown in FIG. 1;
  • FIG. 3 is a side view of a blank used for making the screw shown in FIG. 1;
  • FIG. 4 is an end View of blank shown in FIG. 3;
  • FIG. 5 is a schematic view illustrating the rolling of screw blanks between a pair of fiat faced thread rolling cues
  • FIG. 6 is a schematic view illustrating a rotary thread roller
  • PEG. 7 is a view, partly in section, illustrating a screw driven into a body of metal
  • FIG. 8 is a diagram illustrating one convolution of a thread such as along the line 88 of FIG. 1;
  • FIG. 9 is a planar projection of the spiral curve illustrated in FIG. 8.
  • FIG. 1. cross section of certain threaded members herein dis- FIG. is a view, somewhat schematic, taken along the line 1010 of FIG. 7;
  • FIG. 11 is a view taken along the line 1111 of FIG. 10; 7
  • FIG. 12 isa view taken along the line 12-12 of FIG. 10;
  • FIG. 13 is a view taken along the line 12-12 of FIG. 10, but illustrating the screw in the loaded condition
  • FIG. 14 is a diagram illustrating the outline of one form of blank
  • FIG. 15 is a sectional view of a screw made from a blank of a shape shown in FIG. 14;
  • FIG. 16 is a sectional view taken along the line 16-16 of FIG. 15;
  • FIGS. 17, 18, 19 and 20 are diagrams illustrating the outlines of blank cross-sections according to various 'different further modifications
  • FIGS. 21 to 26, inclusive are side and end views of different additional modifications of thread forming screws constructed in accordance with the present invention.
  • FIG. 27' is a view partly in section illustrating a length of Wire being drawn through a re-forming die
  • FIG. 28 is a sectional view taken along the line 2828 of FIG. 7;
  • FIG. 29 is a view partly in section illustrating the cut off die station of a conventional cold header machine
  • FIG. 30 is a view partly in section illustrating the first, upsetting, station of a cold header machine
  • FIG. 31 is a View partly in section illustrating the final heading station of a cold header machine.
  • Pitch diameter is used as a generic term to designate the diameter i.e., maximum transverse width, of any section of either the pitch cylinder or the pitch cone as determined by the three-wire method of pitch diameter measurement. (See 58, FIG. 10.) Due to the poly o'nal'nature of certain configurations herein discussed, the pitch diameter, i.e., maximum transverse width, does not always extend throughthe axial center of the configuration. V
  • Pitch cylinder is, on a straight thread, an imaginary coaxial'cylinder, the surface of which would pass through thethread profiles, or the projection thereof, at such points as to make the width of the groove, or the projection thereon-equal to one-half the basic pitch. (See 30, Due to the. polygonal configuration of the cussed, the pitch cylinder thereof is not round but of arcuate polygonal cross-sectional shape.
  • Pitch cone on a taper thread is an imaginary coaxial cone, th e surface of which wouldpass through the thread profiles, or the projection thereof, at such points as to make the width of the groove, or the projection thereof, equal to one-half the basic pitch. (See 26, FIG. 1).
  • Pitch diameter cross section as used herein means the transverse cross section of either a pitch cylinder or a pitch. cone, and for reasons-pointed out above it may be of arcuate polygonal configuration.
  • Pitch surface is used herein to designate the surface of revolution of the pitch line defining either the pitch cylinder or the pitch cone as hereinbefore defined.
  • Pitch surface 'cross section is used herein to designate the transverse cross section of any pitch surface, such as that of either the pitch cylinder or the pitch cone, as hereinbefore defined. For reasons mentioned above, it may be of arcuate polygonal configuration.
  • pitch diameter cross section and pitch surface cross section are intended to be synonymous expressions and are used interchangeably herein.
  • the invention will first be described with reference to a screw indicated generally at 20 having a driving head 21 and a straight thread formation 22 on the main shank portion 23 and a tapered thread formation 24 on the work-entering end 25 of the screw.
  • the threaded portion of the screw is of noncircular, or lobular, shape and which may, for convenience, be termed an arcuate polygon, or more specifically, in this instance, an arcuate equilateral triangle.
  • the configuration is characterized by tree equally spaced lobes 2'7, 28 and 29, having a radius of curvature substantially less than one-half the pitch diameter of the screw, the lobes being separated by relatively broad arcuate sides 31, 32 and 33, each having a radius of curvature substantially greater than one-half the pitch diameter ,of the screw.
  • the sides 31, 32 and 33 merge smoothly and continuously with the intervening lobes, 27, 28 and 2?, respectively.
  • FIGS. 3 and 4 there is illustrated a blank which is preformed for use in the manufacture of the screw illustrated in FIGS. 1 and 2.
  • This blank includes a straight shank portion'35 having a driving head 36 at one end, which head may be provided with any driving means as desired, and 'a tapered end 33 at the other.
  • the driving end need not necessarily include an enlarged head, inasmuch as otherforms of driving heads are well known.
  • the blank is also of arcuate triangular shape similar to the configuration illustrated in FIG. 2.
  • the blank the-rein shown is made by working an odd number of uniformly spaced apart surface areas 37 extending longitudinally of a length of metal stock inwardly of such length to a greater extent than the intermediate surface areas 39 and thereby producing a shank portion that is of generally arcuate polygonal cross section of substantially uniform width throughout 360 degrees.
  • the blank can be formed from stock prepared by drawing a length ofround wire 16% through. a forming or sizing die 162 provided with a triangularly shaped orifice 164 of a size and shape desired for the cross section of the blank as illustrated in FIG. 4.
  • the fiow of metal is so con trolled by the die orifice so' as to form the cross section of the Wire with an odd number of symmetrically arranged, arcuate sides.
  • Stock material 166 so formed can then be fed into a conventional cold heading machine 168 wherein predetermined length-s may be severed by cutoff means 179 and an end portion upset and headed with conventional upsetting and heading punches 171 and 1'72.
  • the heading punch 172 can provide either a slot, recess or other driving means such as a hex head, as may be desired, in the upset head portion.
  • a taper 38 may simultaneously be placed on the end of the blank in any manner well known in the art such'as, for example, by providing an inwardly tapering end 174 in the cavity of the heading die 171:, in the event that such a taper i desired in the final article.
  • the form of screw illustrated in FIGS, 25 and 26, for example, does not require any such taper, however.
  • the transverse width of the blank as determined by a micrometer is substantially constant or equal throughout 360 around the blank even though it is not round so that a thread may be generated thereon with readily available centerless thread-forming machines.
  • the blank 35 may be threaded between conventional flat thread-rolling dies 49, 41 as illustrated in MG. 5.
  • the blank 35 may have threads formed thereon as by rolling it between a rotating die 43 and a stationary arcuate die 44- as shown in FIG. 6.
  • the various thread-rolling machines indicated in F368. and 6 are characterized by the fact that they all form threads on a cente-rless basis.
  • the opposed workpiece supporting surfaces are spaced a substantially uniform distance apart throughout the thread-forming operation and which is important for ease and economy of manufacture. It is to be understood, however, that some forms of conventional threadforrning means referred to may be contoured to form certain types of taper threads on the work-entering end, and are also slightly and uniformly inclined toward each other from the starting to the finish ends. During the thread-rolling operation, a continuous thread is formed on both the shank and tapered end portions 35 and 33, respectively, of the blank.
  • the thread particularly on the end portion of the blank, is provided with an arcuate lobular pitch surface configuration, which configuration is substantially the same as that of the corresponding cross sections of the blank, as will be noted by a comparison of FIGS. 2 and 4.
  • a taper is formed on the crest of the thread into its final shape on the end portion, which taper extends inwardly toward the tip thereof.
  • the taper may be formed on the thread over the work-entering end solely during the rolling operation with conventional contoured dies, and without requiring previous tapering of the end of the blank.
  • the line 54 illustrates the peripheral or crest contour of a single spiral revolution of thread on the tapered end 24 of the screw 20.
  • the root of the thread portions which will be formed in a parent body, such as 51, by the crests of the lobes 27a, 28a and 29a may be represented by the circular arcs 55, 56 and 57, the extent of which may be further represented by the arcs D, E and F.
  • From the crests of the lobes the screw thread recedes from contacting engagement with the surfaces of the thread formed in the parent body and hence there is no frictional contact throughout the entire extent of the arcs D, E and F.
  • the working engagement of the lobes 28a, 29a and 2715 with the body of parent material is indicated by the arcs A, B and C.
  • the dotted circle 8 indicates the root diameter of the thread formed by a complete revolution of the lobe 275.
  • FIG. 9 illustrates a planar projection of the single spiral revolution illustrated in FIG. 8.
  • the successive thread lobe crests, 27a, 28a, 2-911 and 27b are indicated.
  • the starting radius, that is, the distance from the axis 6% ⁇ of the screw to the crest of the lobe 2% is indicated at 61 while the distance from such axis to the crest of the dual lobe 27b is represented at 62.
  • the extent of working engagement of the successive lobes 28a, 29a and 2% with the metal of the parent body may be represented by the distances A, B and C, it will be observed that the total engagement amounts to approximately 25% of the total peripheral extent of the screw thread.
  • FIG. 10 is illustrated a schematic sectional view through the shank of the screw, and in which the line 64 indicates the peripheral, or crest edge of the screw thread, 65, the root of the thread While the dotted line as represents the pitch cylinder of the thread.
  • the pitch cylinder is not round but in this instance is of arcuate polygonal crosssectional configuration.
  • the dotted line as is also sometimes referred to hereinafter as representing the pitch surface of the thread inasmuch as considerable of the following description referring to this aspect is applicable to the pitch cone of the thread as Well as to the pitch cylinder there-of.
  • the transverse cross section of this pitch surface as is sometimes, for convenience, referred to hereinafter as the pitch diameter cross section of the thread.
  • the line 67 represents the root of the completed thread formed in a parent body such as 51 and which is a true circle concentric With the screw axis 6:).
  • the radius of the circle 67 corresponds with the distance between the screw axis 6t? and the outermost points on the thread lobes Z7, 23 and 29. It will be obvious that only those portions of the screw threads at the outer portions of the lobes 27, 28 and 29 will be in firm contacting engagement with the threads formed in the parent body and which is furthermore indicated in the sectional view of FIG. 11.
  • the relatively broad sides 31, 32 and 33 of the screw thread will be supported out of engagement with the adjacent threads in the parent body 51 as illustrated in FIG. 12 on account of the outof-round condition of the screw. Accordingly, during driving operation, frictional resistance between the screw and the parent body is reduced to a minimum in the shank portion as Well as in the tapered work-entering portion as previously described.
  • the pitch diameter of the threaded section is represented by the distance 65.
  • the pitch diameter of an arcuate triangular threaded section may be measured by the previously mentioned three-wire method of measurement, as indicated by the wires 46 and 47 in FIGS. 1 and 10. The diameter of these wires is selected so that they will contact the flanks of the threads at the points coinciding with the pitch cylinder indicated at 369 in FIG. 1 and by the line 65 in FIG. 10. In the case of a uniform thread illustrated in FIG.
  • tie contact points will, of course, fall at the midpoints of the sloping thread fiank faces.
  • a suitable micrometer or other measuring device having parallel plane gauge surfaces, the distance between the outer surfaces of the oppositely disposed wires may be measured. From this value, the pitch diameter 68 can readily be computed.
  • the pitch diameter for any section of a pitch cone, such as that indicated at as in FIG. 1, may also be measured similarly by the three-wire method taking into consideration, of course, the angle of taper of the cone at the seC- tion 'being measured. I
  • the thread-forming devices of the present invention are susceptible of considerable variation insofar as the cross-sectional configuration is concerned. Certain basic considerations must be observed, however, in order that the blanks may readily be threaded by available, conventional thread-rolling equipment as previously referred to. To begin with, at least that portion of the blank which is to be provided with lobular threads, as herein disclosed, must be of such cross-sectional shape that it will readily rotate between the opposed threadforming dies. This means that the blank portion should be of substantially uniform width throughout 360. By the term uniform width, it is meant that the crosssection of the blank portion is of'uniform transverse width as determined by a micrometer even though such cross-section is not round.
  • an outline of a blank is shown in its simplest form, namely, in the shape of an arcuate, equilateral triangle 72.
  • Each side of this triangle is arcuate with respect to the intersection of the other two sides as indicated by the radius 73.
  • the triangle 72 is of uniform width throughout 360 and hence may be freely rotated between two parallel surfaces spaced apart a distance corresponding to the length of the radius 73.
  • FIG. is illustrated an approximaiton of the crosssectional shape of the resultant screw after a blank of a shape such as in FIG. 14 has been passed between a pair of flat rolling dies. It will be observed that the lobes 78, 79 and 36 are smoothly rounded with a curvature which merges with the broad sides 82, 83 and 84. On account of the relatively large amount of out-of-round with respect to the blank, as indicated by the distance 74 in 1 16.14,
  • FIG. 17 is illustrated at 9% a further outline configuration for a screw blank in the form of another arcuate equilateral triangle having sides 91,92 and 93, each side having a radius of curvature 94, somewhat greater than one-half the diameter of the circumscribed circle 95.
  • the arcuate triangle therein illustrated comprises broad sides 102, 103 and 104 having a radius of curvature 165. These sides merge'smoothly and tangentially with intermediate arcuate lobes 1%, 109 and 1163 each having a radius of curvature 111. The lobes are internally tangential with respect to the circumscribed circle 114. The maximum clearance between the sides 102, 1&3 and 1M and the circumscribed circle 114 may be indicated by the distance 116. a
  • a blank having a cross-sectional configuration comparable to that illustrated in FIG. 18 will roll smoothly between a pair of flat rolling dies in that the width is substantially uniform throughout 360. Moreover, with an amount of clearance as indicated at 116, threads can readily be completely formed over the sides 162, 103 and 104 as well a across the lobes, 1%, 109 and 110. Moreover a minimum of deformation will occur in cross sectional shape between that shown in FIG. 18 for the blank and that of the finished screw. This is a distinct advantage insofar as commercial practice is concerned since it is thus possible to predict and thus design in advance, within reasonably close limits the final cross-sectional shape of the screw by corresponding design of the blank.
  • the volume of metal which will be raised above the surface of the blank will correspond to the volume of the grooves formed in the blank between the raised thread portions. Accordingly, the blank configuration illustrated in FIG. 18 will conform rather accurately to that of the pitch surface of the finished thread.
  • R equals the radius of curvature 165 of the broad sides such as MP2, 193 and ltl i; r equals the radius of curvature 111 for the lobular portions such as 1%, Hi9 and 11%; C equals the diameter of the circle to which the lobular portions are internal tangents, such as the circle 11 i; and K is the amount the sides of larger radius depart from such a circle, and as indicated by the distance 116.
  • the fractions, 2.741 and 3.741 may be converted to whole numbers 3 and 4, respectively, for use in designing small size blanks.
  • the lobular portions will be defined by sides 7.24, 125 and 126 which are concentric about the axis of the blank or, in other words, segments of the circumscribed circle 12.7 which, for the conditions assumed, is the same diameter as the circle 114-.
  • the amount of clearance, K, between the sides 12%, 121 and 122, and the circle 127, indicated at 128 is the same as the clearance 116.
  • the blank shape illustrated in FIG. 19 conforms very closely to the shape illustrated in PEG. 18 or, in other words, the deviation occasioned by the concentric portions 124, 125 and 126 as distinguished from the portions 108, 109 and 11d of lesser arcuate curvature is so slight as to be hardly noticeable, and especially in the smaller sized screw blanks.
  • this minor discrepancy disappears entirely in that the cross-sectional shape of the finished screw blank does conform to the shape illustrated in FIG. 18. In other words, in the finished screw, no part of the lobes will be concentric with the screw axis.
  • arcuate lobular configuration or arcuate polygonal cross section, of substantially uniform width throughout 360 degrees, and the like, as used herein and especially in the claims, it is intended to include all such shapes as approximate an arcuate polygonal configuration so that the blank will roll smoothly between conventional thread-rolling dies as previously described, and still form pronounced lobes in the finished product.
  • the factor K employed in the above formulas that is, the maximum amount of clearance between the threads of the screw and of the parent body, is indicated in FiG. 12.
  • the extremities of the threads that is, the crests roots
  • Usual- 1y these extremities are imperfectly formed and, consequently, they do not provide reliable reference points for the determination of the amount of the factor K.
  • the pitch cylinder for the screw Zti is indicated by the dotted line while the pitch cylinder for the thread formed in the body 51 is indicated by the dotted line 136.
  • the difference in the diameters of the cylinders 135i and 136 may also be represented by the same factor K.
  • the value of the factor C in the above formulas is determined by the size of the screw to be provided, the value of the factor K may be varied as desired.
  • the optimum value for the factor K is arrived at as a compromise between two opposing conditions.
  • the condition illustrated therein represents the unloaded condition of the screw relative to the body 51.
  • FIG. 13 represents the loaded condition, that is, the screw driven home tightly, the opposing forces being represented by the arrows 137 and 138.
  • the lobular portions of the screw will be Brinelled, that is, slightly indented, into the formed threads in the parent body 51 until the flanks 139 of the screw 20 are drawn into substantial engagement with the corresponding adjacent flanks 140 of the body 51.
  • maximum resistance is provided against the tendency for the threads of either one or the other interengaged elements from stripping. It will also be obvious that the greater the areas of engagement between the flanks 139 of the screw and the adjacent thread flanks 140 of the parent body, the greater will be the stripping resistance.
  • the value selected for the factor K may be varied somewhat depending upon the size of the screw being manufactured and other factors.
  • K the following values for K for the most common screw sizes provides an excellent compromise between low driving torque on the one hand, and high stripping torque, or holding power, on the other hand, and with a wide differential therebetween providing an ample range within which automatic clutches for power screw drivers can be adjusted for insuring that the screws may be driven firmly home before disengagement of the clutch and at the same time being assured that disengagement of the clutch will take place before the threads are stripped.
  • Screw size Value of K (inches) 2 .0035 3 .004 4 .005 6 .006 8 through 1 .009
  • K a value of K corresponding approximately from one-fourth to one-half of the thread depth in order to obtain a high value of holding power per thread and at the same time provide for low driving torque. It will be obvious that the holding power per thread of the screw will diminish very considerably as the amount of overlap of adjacent threads, as illustrated in FIG. 13, decreases. While the limit is not critical, the amount of overlap at the low points of the sides of the screw should be at least approximately one-third of the thread height.
  • the difference between the distance from the axis to the farthest points on the lobes of the pitch cylinder and the distance from the axis to the nearest points on the sides of the pitch cylinder should not be substantially greater than two-thirds of the thread height.
  • the amount of K may be greater.
  • V and 104 with a radius of curvature 105 which is greater than one-half the pitch diameter, i.e., the transverse width of the pitch surface,,the latter being equal to the sum of the radii 105 and 111.
  • the pitch diameters of the pitch cylinder do not pass through the'center of the pitch surface throughout 360 degrees. As shown in FIGURE 18, however, all pitch will pass through the point 117, and all pitch diameters measured across the side 104 and lobe 109 will .pass through the point'101.
  • the difference between the minimum and maximum radial dimensions of any pitch diameter cross section is preferably held to an amount not substantially more than two-thirds the depth of the thread on the shank portion.
  • the maximum radial dimension of the pitch surface 66 is indicated, for example, by the distance from point G to the center 60.
  • the minimum radial dimension of the pitch surface 66 is indicated for example, by the distance from point H to the center 60.
  • the difference in these two dimensions corresponds substantially to the distance 70.
  • this difference may preferably be held to an amount not substantially more than twothirds, and not substantially less than one-quarter, the depth of the thread.
  • the peripheral extent of the lobes, 108, 109 and 110 is substantially less than one-half of the extent of each of the sides 102, 103 and 104, and which may be represented by the linear distance 107, respectively.
  • the sum of'the linear distances 106 of the three lobes is approximately equal to twenty-five (25%) percent of the peripheral extent of the pitch cylinder illustrated. It is to be understood that in case of a reduction in the, amount of K, the extent 106 of the lobes is increased with a corresponding reduction in the extent 107 of the intermediate sides 102, 103 and 104.
  • the cross-sectional shape for all the various modifications of blanks were of arcuate equilateral triangular configuration.
  • the cross sectional shape may be either five or seven sided.
  • FIG. 20 is illustrated a five sided cross-sectional configuration.
  • the configuration in 'thisinstance consists of five equiangularly spaced apart sides 142 with intermediate lobe-s 143.
  • the radius of curvature of the sides 142 is approximately equal to the diameter of the circumscribed circle 144 while the radius of curvature of the lobes 143, as in previous instances, is less than one-half of such diameter and actually approximately one-fourth thereof.
  • the lobular segments between the sides 142 may consist of segments of the circle 144, as in the case of the blank configuration described above with reference to the diagram of FIG. 19. While the poly,,, onal shapes of five or seven sides might be advisable for large size threaded members such as, for example, above /2 in diameter, I prefer to use the three sided polygonal shapes for smaller diameters.
  • the screw illustrated in FIG. 1 has a thread formation of the vanishing type in that, in its work-entering end portion 25 it is characterized in any axial plane by a constant root diameter and progressively decreasing outside and pitch diameters.
  • the screw 145 is provided with a thread formation 146 which is also of the vanishing type in the end portion thereof.
  • the thread in the work-entering end portion 147 is further characterized, in any axial plane, by decreasing root, pitch and outside diameters.
  • the pitch cylinder of the thread formation on the shank is indicated by the dotted lines 181;
  • the pitch cone of the work-entering end portions is indicated by the dotted lines 182. It will be noted that the inwardly tapering sides of the cone, as viewed in longitudinal section, are curved rather than straight.
  • Both the pitch cylinder 181 and the pitch cone 182 are of lobular cross-sectional configuration, as is readily apparent from the end View of FIG. 22, and moreover, every transverse cross section of such pitch surfaces is of equal transverse width throughout 360 degrees.
  • FIGS. 23 and 24 is illustrated a screw 149 having a thread formation 150 which is finished or completely formed in its main shank portion but which is unfinished in its work-entering end portion 151 where the thread formation in any'axial plane is characterized by a constant root and pitch diameter and a decreasing outside diameter.
  • the pitch cylinder of the thread formation 150 and 151 is indicated by dotted lines 184.
  • the pitch cylinder as is apparent from the end view of FIG. 24, is of lobular cross-sectional configuration and is of equal transverse width throughout 360 degrees and throughout the entire length of the shank and work-entering end portions.
  • FIGS. 25 and 26 is illustrated a further form of screw 155 which is provided with a finished thread over its main shank portion and an unfinished thread over its work-entering end portion 157.
  • This screw in any axial plane, in its work-entering end portion 157, has a constant pitch diameter while the root diameter increases in the direction toward the outer end 158 while the outside diameter progressively decreases toward the same outer end.
  • the pitch cylinder of the thread formation throughout the entire length thereof is indicated by dotted lines 186.
  • This pitch cylinder is of l-obular cross-sectional configuration and is of equal transverse width throughout 360 degrees throughout both the shank and work-entering end portions.
  • the device in this instance is formed through the use of contoured thread-rolling dies in conjunction with an untapered blank, that is, a blank of lobular cross section but of uniform transverse width throughout its entire length.
  • This screw is of the so-called captive type in that when it is threaded into a pilot hole having a diameter only slightly larger than the extremity 158 of the screw, the female thread formed in the parent body increases progressively at a rate comparable to the decrease in the root diameter of the threa of the screw so that the fully for-med thread in the parent body has an internal crest diameter which is smaller than the diameter of the screw end 158.
  • the reforming pressures being applied by an amount such that the difference in the distance from the axis of the part to the center of first mentioned areas and to the center of the intermediate areas is not substantially more than two-thirds and not substantially less than one-quarter the depth of the fastener thread, whereby to form a shank portion which is of arcuate polygonal cross-section of substantially uniform width throughout 360 degrees,

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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  • Forging (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
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  • Mixers Of The Rotary Stirring Type (AREA)
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US115846A 1961-06-27 1961-06-27 Method of producing thread swaging devices Expired - Lifetime US3195156A (en)

Priority Applications (11)

Application Number Priority Date Filing Date Title
US115846A US3195156A (en) 1961-06-27 1961-06-27 Method of producing thread swaging devices
DE1961R0031282 DE1400229C2 (de) 1961-06-27 1961-10-13 Selbstgewindeherstellende Schraube
SE10341/61A SE341295B (da) 1961-06-27 1961-10-18
AT793261A AT242447B (de) 1961-06-27 1961-10-20 Selbstgewindeherstellende Schraube
BE609563A BE609563R (fr) 1961-06-27 1961-10-25 Vis auto-taraudantes
CH1247861A CH386182A (fr) 1961-06-27 1961-10-26 Vis à filet auto-taraudant et procédé de fabrication de cette vis
DK427361AA DK134413B (da) 1961-06-27 1961-10-27 Selvskærende skrue.
NO141974A NO115459B (da) 1961-06-27 1961-10-31
ES271676A ES271676A1 (es) 1961-06-27 1961-10-31 Perfeccionamientos en sujetadores autoaterrajadores
FR877628A FR81507E (fr) 1961-06-27 1961-10-31 Vis auto-taraudantes
US590699A US3918345A (en) 1961-06-27 1966-10-31 Thread forming fasteners

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BE (1) BE609563R (da)
CH (1) CH386182A (da)
DE (1) DE1400229C2 (da)
DK (1) DK134413B (da)
ES (1) ES271676A1 (da)
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Cited By (43)

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US3263533A (en) * 1964-08-27 1966-08-02 Textron Ind Inc Screw extractor
US3295154A (en) * 1965-02-18 1967-01-03 Besly Welles Corp Metal swaging tool and method of seating and threading a thin walled cylinder in a hole
US3318182A (en) * 1965-11-03 1967-05-09 Textron Ind Inc Self-thread-forming screw with drill point and method of making same
US3385340A (en) * 1966-04-22 1968-05-28 Lock Thread Corp Lock fastener
US3461470A (en) * 1966-07-07 1969-08-19 Fastron Co Thread-forming screw and method of making the same
US3537288A (en) * 1965-10-22 1970-11-03 P D Robertson Mfg Co Ltd Method of manufacturing self-tapping screws
FR2075624A5 (da) * 1970-01-19 1971-10-08 Res Engineering Man
US3772720A (en) * 1970-04-11 1973-11-20 Res Engine Manuf Inc Method for making a thread forming member
US3802015A (en) * 1972-01-10 1974-04-09 Res Eng Mfg Inc Tap
US3803889A (en) * 1970-01-19 1974-04-16 Res Eng Mfg Inc Self-thread forming threaded fasteners and method for making same
US3818749A (en) * 1972-10-02 1974-06-25 Nl Industries Inc Thread rolling dies and method of manufacturing same
US3827331A (en) * 1972-11-01 1974-08-06 Res Eng & Mfg Self-extruding screw
US3875780A (en) * 1974-01-03 1975-04-08 Rockford Headed Products Method of making a thread forming screw
DE2452825A1 (de) * 1973-12-07 1975-06-12 Res Eng & Mfg Schraube
US3935785A (en) * 1974-01-03 1976-02-03 Rockford Headed Products, Inc. Thread swaging screw
US3939683A (en) * 1974-11-28 1976-02-24 Geffen Johannes Adrianus Van Piercing tools
US3985172A (en) * 1971-06-17 1976-10-12 General Motors Corporation Panel extruding nut and assembly
US4028987A (en) * 1973-07-18 1977-06-14 Illinois Tool Works Inc. Self-drilling screws
US4040328A (en) * 1976-03-10 1977-08-09 Research Engineering & Manufacturing, Inc. Thread-forming fastener having dual lobulation and dies for making the same
FR2365052A1 (fr) * 1976-09-16 1978-04-14 Res Eng & Mfg Goupille lobee
US4112812A (en) * 1971-03-25 1978-09-12 Research Engineering & Manufacturing, Inc. Heat-treated article
US4170050A (en) * 1978-06-07 1979-10-09 Groov-Pin Corporation Method of making lobular internally and externally threaded insert
US4235149A (en) * 1978-08-17 1980-11-25 Veldman Donald R Self-thread creating fastener and method and apparatus for making the same
EP0057039A1 (en) * 1981-01-22 1982-08-04 Flowdrill B.V. Flow drill for the provision of holes in sheet material
US4353233A (en) * 1981-01-29 1982-10-12 Amca International Corporation Dies for making thread-forming fasteners
US4480506A (en) * 1980-02-19 1984-11-06 Research Engineering & Manufacturing Apparatus for generating lobular polygonal forms
US4546639A (en) * 1983-09-26 1985-10-15 Colt Industries Operating Corp Thread rolling dies for forming self tapping screws and the like
US4862718A (en) * 1988-07-14 1989-09-05 Sps Technologies, Inc. Thread rolling dies
US5842923A (en) * 1995-06-14 1998-12-01 Minebea Kabushiki-Kaisha Screw and method for its production
US6089806A (en) * 1999-01-25 2000-07-18 Conti Fasteners Blank for self-tapping fastener
US6499724B1 (en) 1994-07-18 2002-12-31 Tka Fabco Corp. Safety latch for a tire carrier
US6547219B2 (en) 1991-01-10 2003-04-15 Tka Fabco Corp. Safety latch for a tire carrier and improvements therefor
US20090010734A1 (en) * 2006-03-16 2009-01-08 Channg Chin Industry Corp. Screw
US20120070247A1 (en) * 2010-09-21 2012-03-22 Sanohatsu Co., Ltd. Method for manufacturing fastening screw and fastening screw
US20130047414A1 (en) * 2010-01-06 2013-02-28 Bernd Werthwein Thread-forming Screw And Use Thereof
TWI498490B (zh) * 2007-08-13 2015-09-01 Res Eng & Mfg 螺紋鎖固／常置扭力固定件及固定件總成
US10125805B2 (en) * 2015-04-21 2018-11-13 Sungwoo Hitech Co., Ltd Rivet screw drill
US20200208670A1 (en) * 2018-12-31 2020-07-02 Robert E. Stewart Faceted lobular threads
USD906099S1 (en) * 2019-02-26 2020-12-29 Winter Equipment Company Carriage bolt
US10914556B2 (en) 2017-09-30 2021-02-09 Robert E. Stewart Mounting and fastening system clamp and clamp assembly
US20210108664A1 (en) * 2019-10-10 2021-04-15 Research Engineering & Manufacturing, Inc. Thread forming and thread locking fastener
US11156248B2 (en) 2015-11-12 2021-10-26 Arnold Umformtechnik Gmbh & Co. Kg Thread-forming screw
GB2564450B (en) * 2017-07-11 2022-07-20 Tite Range Dev Ltd A fastener

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EP0004541A1 (de) * 1978-02-17 1979-10-17 B E L I P A R, Société Anonyme Schraube, insbesondere Gewindeformschraube und Walzwerkzeug zur Herstellung derselben
US4194430A (en) * 1978-05-05 1980-03-25 Research Engineering & Manufacturing, Inc. Thread-forming screw with step taper
DE3046692C2 (de) * 1980-12-11 1986-01-23 Kamax-Werke Rudolf Kellermann Gmbh & Co Kg, 3360 Osterode Gewindefurchende Schraube
FR2584464B1 (fr) * 1985-07-05 1989-05-26 Laurent Sa Tige filetee, telle qu'une vis, et son procede de fabrication
DE4015771A1 (de) * 1990-05-16 1991-11-28 Sfs Stadler Holding Ag Gewindefurchende schraube
DE102006058464B4 (de) * 2006-06-07 2011-02-24 Knipping Verbindungstechnik Gmbh Schraube

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Cited By (54)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3263533A (en) * 1964-08-27 1966-08-02 Textron Ind Inc Screw extractor
US3295154A (en) * 1965-02-18 1967-01-03 Besly Welles Corp Metal swaging tool and method of seating and threading a thin walled cylinder in a hole
US3537288A (en) * 1965-10-22 1970-11-03 P D Robertson Mfg Co Ltd Method of manufacturing self-tapping screws
US3318182A (en) * 1965-11-03 1967-05-09 Textron Ind Inc Self-thread-forming screw with drill point and method of making same
US3385340A (en) * 1966-04-22 1968-05-28 Lock Thread Corp Lock fastener
US3461470A (en) * 1966-07-07 1969-08-19 Fastron Co Thread-forming screw and method of making the same
FR2075624A5 (da) * 1970-01-19 1971-10-08 Res Engineering Man
US3803889A (en) * 1970-01-19 1974-04-16 Res Eng Mfg Inc Self-thread forming threaded fasteners and method for making same
US3772720A (en) * 1970-04-11 1973-11-20 Res Engine Manuf Inc Method for making a thread forming member
US4112812A (en) * 1971-03-25 1978-09-12 Research Engineering & Manufacturing, Inc. Heat-treated article
US3985172A (en) * 1971-06-17 1976-10-12 General Motors Corporation Panel extruding nut and assembly
US3802015A (en) * 1972-01-10 1974-04-09 Res Eng Mfg Inc Tap
US3818749A (en) * 1972-10-02 1974-06-25 Nl Industries Inc Thread rolling dies and method of manufacturing same
US3827331A (en) * 1972-11-01 1974-08-06 Res Eng & Mfg Self-extruding screw
US4028987A (en) * 1973-07-18 1977-06-14 Illinois Tool Works Inc. Self-drilling screws
DE2452825A1 (de) * 1973-12-07 1975-06-12 Res Eng & Mfg Schraube
US3875780A (en) * 1974-01-03 1975-04-08 Rockford Headed Products Method of making a thread forming screw
US3935785A (en) * 1974-01-03 1976-02-03 Rockford Headed Products, Inc. Thread swaging screw
US3939683A (en) * 1974-11-28 1976-02-24 Geffen Johannes Adrianus Van Piercing tools
US4040328A (en) * 1976-03-10 1977-08-09 Research Engineering & Manufacturing, Inc. Thread-forming fastener having dual lobulation and dies for making the same
DE2706246A1 (de) * 1976-03-10 1977-09-22 Res Eng & Mfg Gewindeformender befestiger
FR2365052A1 (fr) * 1976-09-16 1978-04-14 Res Eng & Mfg Goupille lobee
US4106877A (en) * 1976-09-16 1978-08-15 Research Engineeering & Manufacturing, Inc. Lobular pin
US4170050A (en) * 1978-06-07 1979-10-09 Groov-Pin Corporation Method of making lobular internally and externally threaded insert
US4235149A (en) * 1978-08-17 1980-11-25 Veldman Donald R Self-thread creating fastener and method and apparatus for making the same
US4480506A (en) * 1980-02-19 1984-11-06 Research Engineering & Manufacturing Apparatus for generating lobular polygonal forms
EP0057039A1 (en) * 1981-01-22 1982-08-04 Flowdrill B.V. Flow drill for the provision of holes in sheet material
US4353233A (en) * 1981-01-29 1982-10-12 Amca International Corporation Dies for making thread-forming fasteners
US4546639A (en) * 1983-09-26 1985-10-15 Colt Industries Operating Corp Thread rolling dies for forming self tapping screws and the like
US4862718A (en) * 1988-07-14 1989-09-05 Sps Technologies, Inc. Thread rolling dies
US6547219B2 (en) 1991-01-10 2003-04-15 Tka Fabco Corp. Safety latch for a tire carrier and improvements therefor
US6499724B1 (en) 1994-07-18 2002-12-31 Tka Fabco Corp. Safety latch for a tire carrier
US5842923A (en) * 1995-06-14 1998-12-01 Minebea Kabushiki-Kaisha Screw and method for its production
US6089806A (en) * 1999-01-25 2000-07-18 Conti Fasteners Blank for self-tapping fastener
US6089986A (en) * 1999-01-25 2000-07-18 Conti Fasteners, A.G. Die for forming self-tapping fastener blank
WO2000043683A1 (en) 1999-01-25 2000-07-27 Conti Fasteners A.G. Improved self-tapping thread fastener and a blank therefor
US20090010734A1 (en) * 2006-03-16 2009-01-08 Channg Chin Industry Corp. Screw
TWI498490B (zh) * 2007-08-13 2015-09-01 Res Eng & Mfg 螺紋鎖固／常置扭力固定件及固定件總成
US20130047414A1 (en) * 2010-01-06 2013-02-28 Bernd Werthwein Thread-forming Screw And Use Thereof
US8939692B2 (en) * 2010-01-06 2015-01-27 Arnold Umformtechnik Gmbh & Co. Kg Thread-forming screw and use thereof
CN102554109A (zh) * 2010-09-21 2012-07-11 株式会社友荣精密 连接螺钉的制造方法及连接螺钉
US20120070247A1 (en) * 2010-09-21 2012-03-22 Sanohatsu Co., Ltd. Method for manufacturing fastening screw and fastening screw
US10125805B2 (en) * 2015-04-21 2018-11-13 Sungwoo Hitech Co., Ltd Rivet screw drill
US11156248B2 (en) 2015-11-12 2021-10-26 Arnold Umformtechnik Gmbh & Co. Kg Thread-forming screw
GB2564450B (en) * 2017-07-11 2022-07-20 Tite Range Dev Ltd A fastener
US10914556B2 (en) 2017-09-30 2021-02-09 Robert E. Stewart Mounting and fastening system clamp and clamp assembly
US10921096B2 (en) 2017-09-30 2021-02-16 Robert E. Stewart Mounting and fastening system and mounting adapter
US11054223B2 (en) 2017-09-30 2021-07-06 Robert E. Stewart Mounting and fastening system rail
US11287223B2 (en) 2017-09-30 2022-03-29 Robert E. Stewart Mounting and fastening system mounting adapter
US20200208670A1 (en) * 2018-12-31 2020-07-02 Robert E. Stewart Faceted lobular threads
US11686337B2 (en) * 2018-12-31 2023-06-27 Robert E. Stewart Faceted lobular threads
USD906099S1 (en) * 2019-02-26 2020-12-29 Winter Equipment Company Carriage bolt
US20210108664A1 (en) * 2019-10-10 2021-04-15 Research Engineering & Manufacturing, Inc. Thread forming and thread locking fastener
US11125262B2 (en) * 2019-10-10 2021-09-21 Research Engineering & Manufacturing, Inc. Thread forming and thread locking fastener

Also Published As

Publication number Publication date
AT242447B (de) 1965-09-10
NO115459B (da) 1968-10-07
DE1400229C2 (de) 1970-08-06
DK134413B (da) 1976-11-01
DE1400229B1 (de) 1969-12-18
CH386182A (fr) 1964-12-31
SE341295B (da) 1971-12-20
ES271676A1 (es) 1962-03-01
BE609563R (fr) 1962-02-15
DK134413C (da) 1977-04-04

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