Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B15/00—Screwdrivers
  • B25B15/001—Screwdrivers characterised by material or shape of the tool bit
  • B25B15/002—Screwdrivers characterised by material or shape of the tool bit characterised by material used or surface finishing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B15/00—Screwdrivers
  • B25B15/001—Screwdrivers characterised by material or shape of the tool bit
  • B25B15/004—Screwdrivers characterised by material or shape of the tool bit characterised by cross-section
  • B25B15/005—Screwdrivers characterised by material or shape of the tool bit characterised by cross-section with cross- or star-shaped cross-section

Definitions

• the invention relates to screwdriver bits of the type specified in the preamble of claim 1, in particular for use in power screwdrivers.
• Screwdriver bits of this type have hitherto been produced from alloyed tool steels, which usually contain a carbon content and alloy additives such as silicon, manganese, chromium, molybdenum and vanadium in proportions of less than 1%. After tempering, these steels have a service hardness of approx. 60 to 64 HRC. When used in power screwdrivers, the screwdriver bits made of tool steel are subject to relatively high wear at the tip of the function, because the stress is higher than with a handheld screwdriver. When using screwdrivers in the commercial sector, in particular also for screw assembly in automated production, the aim is to achieve longer service lives for screwdriver inserts.
• screwdriver bits were made from high-speed steel, which has significantly higher alloy proportions of tungsten, cobalt, molybdenum and similar metals. Although this results in greater hardness, this is associated with increased brittleness. This is particularly important because screwdriver bits made from high-speed steel can only be machined. Because of certain profiles, e.g. B. Phillips profiles, specified, relatively sharp-edged profiling and the structure of the base material interrupted during machining of the profile, screwdriver bits made from high-speed steel do not achieve the torques required by standards and in practice, so that the emdimg sections are reached before they are reached break off these torques brittle.
• US Pat. No. 3,393,722 describes a screwdriver for cross-head screws, which consists of a shaft made of relatively soft steel and a tip part made of an extremely hard material. Both parts are connected by welding.
• the tip part is preferably made of hard metal (tungsten carbide).
• the screwdriver or screwdriver bits of this type have not become known on the market, although more than 30 years have passed since the registration and the increasing demand for wear-resistant screwdrivers or screwdriver bits is promoting the market fit.
• the tip part is preformed by powder metallurgical manufacturing. No information is given about the manufacture, shape and dimensions of either font. It can be assumed that no manufacturing process was found for these versions, which led to satisfactory results.
• Emdrmgab sections in addition to the high hardness also have sufficient toughness so that the torques required in practice are transmitted, at the same time, however, a significantly higher wear resistance or service life is achieved compared to known types of construction and inexpensive production is possible.
• the screwdriver inserts in one part as in DE 92 11 907 Ul, DE 42 41 005 AI and DE 43 00 446 AI, but in two parts with one short front part made of hard metal and a drive part made of steel.
• the hard metal Front part is given an overall length, which is essentially determined by the length of an emdring part, which is dimensioned such that it corresponds to the maximum depth of penetration of the cross recess in screw heads of the assigned size, plus a certain surcharge.
• the compacts reach sintering without cracks, which is necessary for good durability, particularly of cross tips.
• the metal powder pressed under high pressure into the die or the resulting compact apparently opposes its removal from the mold with a high resistance, which is greater the larger the surface of the compact.
• This resistance to demolding must be overcome by the force of the ejector or lower punch acting on the central tip.
• the high specific load on the tip and the ejector force acting on the crossbars can lead to the formation of fine cracks, which are not compensated for even during sintering and disrupt the homogeneity of the structure.
• the required ejector force is significantly reduced, so that, for. B. a complicated, expensive mold can be avoided, in which the lower punch not only has the profile of the central tip, but also the profile of the conical back of the crossbars, as is the case with the known method explained above
• FIG. 1 to 3 are schematic longitudinal sections through three differently sized front parts of a screwdriver insert according to the invention for Phillips screws, the webs each being shown rotated by 45 ° about the longitudinal axis;
• Fig. 4 is a schematic side view of a front part according to the invention, formed analogously to Figures 1 to 3;
• FIG. 7 shows a partially sectioned side view of a screwdriver insert according to the invention with a front part according to FIGS. 4 to 6;
• FIG. 8 and 9 roughly schematically a pressing tool for producing a front part according to the invention according to FIG. 4;
• FIG. 10 shows an enlarged side view of the front part according to FIG. 4 in combination with an associated screw head shown in section;
• FIG. 11 shows a view corresponding to FIG. 7 of a second exemplary embodiment of a screwdriver insert according to the invention
• Fig. 12 is a section along the line XII-XII of Fig. 11;
• FIGS. 13 to 16 partially cut or uncut front views of three further exemplary embodiments of connection forms of the front part made of hard metal with the drive part; 17 to 19 screwdriver bits for Phillips screws of different sizes;
• FIG. 20 shows an embodiment of the screwdriver insert according to the invention, corresponding to FIG. 7, but with a convex anchoring element projecting from the drive part;
• FIG. 22 shows a screwdriver insert for Phillips screws corresponding to FIG. 17 with a further embodiment of the anchoring element
• FIG. 25 shows an embodiment analogous to FIG. 22, but with a front part for Pozidriv screws (PZ);
• 26 to 28 are views corresponding to FIGS. 22 to 24 of a further screwdriver insert for Phillips screws;
• 29 shows a partial, greatly enlarged longitudinal section through a front part of a screwdriver insert according to the invention for TORX screws;
• FIG. 30 is a top view (front view) of the screwdriver bit according to FIG. 29;
• FIG. 31 shows a side view and a front view of a screwdriver insert according to the invention for TORX screws with an outlet radius
• FIG. 32 each shows a side view and a front view (top view) of a screwdriver insert according to the invention for hexagon screws with an outlet radius;
• 33 is a side and front view of a screwdriver according to the invention Insert for Robertson screws with outlet radius;
• FIG. 34 shows a side view of a screwdriver insert according to the invention for TORX screws without outlet radii, the diameter of a penetration tip being larger than the diameter of a drive part;
• FIG. 36 shows a side view of a screwdriver insert according to FIG. 34 with an associated screw head shown in section;
• 39 is a table with preferred dimensions for the front parts of the screwdriver bits according to the invention.
• Fig. 1 shows a front part 1 of a screwdriver bit according to the invention.
• the front part 1 is provided at its front end with an earring section 2 in the form of a conventional cross tip, which is used for penetration into the corresponding inner profile of a Phillips screw.
• the cross tip contains four cross-shaped ribs or webs 3 with upper edges 4, which converge towards each other in a conical shape and end at a flattened end section 5 which is insignificant for the purposes of the invention.
• At the outlet 8 includes a z. B. cylindrical base portion 9, which ends at a rear end face 10, which is generally perpendicular to a central or axis of rotation 11 of the front part. From the end face 10 there is a processing section 12 in the form of a pin, which has a reduced cross section compared to the base section 9, the sealing section 2, the base section 9 and the anchoring section 12 being arranged coaxially to the axis 11.
• This grand shape of the front part 1 is essentially the same for all screwdriver inserts of the invention, but the outer design and the dimensions of the various sections 2, 4 and 6 in particular on the inner profile of the respectively assigned screw and the sections 12 on the selected one Anchorage type must be adapted, as explained below.
• FIG. 2 shows a front part 1 analogous to FIG. 1 and its dimensions essential for the invention.
• a measure LO denotes the length of the Emdringäbmale 2 between the end section 5 and the outlet 8
• Ll the length of the front part 1 between the end section 5 and the end face 10
• LP the profile length, which is the sum of the length LO and the length of the Spout 8 results
• a screwdriver insert is assembled from the separately produced front part 1 (FIGS. 4 to 6) and a likewise separately produced drive part 14 (FIG. 7), which, for. B. for attaching the insert in the feed Serving screwdriver.
• the front part 1 is made of hard metal, while the drive part 14 is made of a tool steel that is customary for this purpose.
• the drive part 14 is on a front side facing the front part 1 with an incorporated in its surface, with its inner cross section to the outer cross section of the
• Anchoring part 12 provided recess 15. The connection then takes place in that the anchoring part 12 is inserted into the recess 15 and pressed, soldered or fastened in this way in such a way that the drive part 14 can transmit the required torques to the front part 1.
• 7 shows, the recess 15 in a z. B. cylindrical or slightly conical transition section 16, which adjoins a section 17 with a conventional hexagonal outer profile of the drive part 14 and causes a flush transition from section 17 to base section 9.
• the front part 1 is produced with the aid of a pressing tool 19, which is indicated schematically in FIGS. 8 and 9.
• a pressing tool 19 which is indicated schematically in FIGS. 8 and 9.
• This includes a pressing bush 20, which at one end has a z. B. cylindrical receiving opening 21 for a z. B. also cylindrical press ram 22 and at the other end with a press die 23 inserted into it, which on a coaxial opposite side of the receiving opening 21 as a negative mold 24 for the front part 1 to be produced, d. H. is designed in the exemplary embodiment as a negative shape for a cross tip.
• the press bushing 20 has a cavity 26 between the negative mold 24 and the receiving opening 21.
• the die 20 is provided with a central passage into which an ejector 25 is inserted.
• the press die 22 is provided on its end face facing the press die 22 with a recess 27 which is designed as a negative form of the anchoring part 12.
• the cavity 26 is first filled with the desired hard metal powder when the ejector 25 is inserted and pushed up to the pressing die 24, as is indicated in FIG. 8 by the reference numeral 28.
• the press ram 22 is inserted into the receiving opening 21 and pre-pressed with the pressure required to compress the hard metal powder 28 in the direction of the press die 23, as a result of which the hard metal powder 28 is compressed and shaped into the shape of the front part 2 (FIG. 9). brought.
• the press die 22 is removed, the ejector 25 is advanced in order to eject the front part 2 from the press die 22 and the press bush 20, and the front part 2 obtained in such a pressing method, for. B.
• the hard metal powder mixture contains e.g. B. cobalt, molybdenum, and tungsten carbide and possibly proportions of iron and leads through the pressing and sintering process to an extremely hard and wear-resistant front part 2.
• the two-part design of the screwdriver inserts 2, 14 according to the invention ensures that the actual functional or effective zone, which is contained in the front part 1, is produced using a comparatively simple, inexpensive method, but with the optimum pressing conditions nevertheless can be achieved. After the front part 1 has been connected to the drive part 14, a screwdriver insert is then produced which also withstands high loads.
• the front part 1 In order to achieve a uniform pressure distribution and thus a homogeneous structure in the front part 1, it is considered necessary within the scope of the invention to design the front part 1 as small as possible in order to cause the lowest possible friction losses in the tool 19. Since the shape and size of the actual penetration section 2 depends on the inner profile in the head of the respectively assigned screw, the following considerations are used to achieve this goal:
• FIG. 10 shows a front part 1 according to FIGS. 1 to 7, which dips into the profiled opening of a screw head 29, which has a depth of penetration T which is smaller than the length L0 of the sealing portion 2.
• the length L0 for each screw size is dimensioned according to the screw head that has the greatest depth of penetration T according to the respective standard or other regulation.
• the type of screw whose head shape gives the greatest depth of penetration T is assumed. These are in the case of Phillips screws z. B. raised countersunk screws according to EN-ISO 7047. Since the penetration depth T is significantly smaller for all other screw types, fit using the Countersunk tapping screws also measure inserts on the heads of other screws that have the same inner profile.
• the screw with the greatest penetration depth T is selected for the dimensioning of LO.
• Size 2 with cross recess have differently standardized penetration depths of the gauge, to which the areas T ⁇ N to T ⁇ x from 1.48 / 1.93 mm to 2.9 / 3.35 mm are assigned.
• the largest occurring area of the largest screw head shape is used for the dimensioning of LO, in that LO receives the value 3.35 mm. This ensures that the front part 1 can dip into all screw heads with full penetration depth T.
• An advantage of this way of measuring LO is that LO is not made larger than is required for the desired function.
• the size of Ll for cross recess profiles depends, among other things, on how large the values for LP and LB (FIG. 2) should be, and it is clear that the maximum value for Ll is the respective dimension of L0. With regard to LP, it has proven expedient to choose the outlet 8 to be significantly smaller than is possible with conventional bits.
• Size 1 Here the range ET ⁇ N to ET ⁇ x-is 1.22 to 1.47 mm for smaller and 1.83 to 2.08 for larger screw heads.
• L0 2.1 mm
• LP 3.0 mm
• Ll 3.8 mm are selected.
• Size 3 The range ⁇ T mN to ET ⁇ x is between 2.73 mm and 3.18 mm.
• L0 4.4 mm
• LP 6.6 mm
• Ll 8.1 mm
• screw heads e.g. B. Type H (Phillips) according to EN-ISO 7045 - 7047
• EN-ISO 7045 - 7047 can be used in a corresponding manner.
• the base section 9 consists of a short, plate-shaped section, which mainly serves to form the anchoring elements 12. These can consist of convex, protruding from the end face 10 (FIG. 1) or of concave, sunk into the end face 10. Some exemplary embodiments are explained in more detail below with reference to FIGS. 11 to 24, in which the front parts 1 essentially up to partially different base sections correspond to the front part 1 according to FIGS. 1 to 9. In an analogous manner, the drive parts 14 essentially correspond to the drive part 14 according to FIG. 7, which is why only the different parts are designated with different reference numerals than previously. 1 to 9 is a cylindrical pin, the front part 1 in FIGS.
• an anchoring anchoring element 31 projecting perpendicularly from the other end face of the base section 9 with a TORX profile, which is inserted into a recess 32 of the drive part 14 is used, which has a corresponding inner profile.
• the firm connection of the two parts 1.14 takes place, for. B. by gluing, soldering, pressing or the like.
• the non-circular cross-section of the anchoring elements 31, 32 has the advantage that a non-rotatable, the transmission of high torques enabling connection is achieved by positive locking.
• FIG. 13 shows a concave anchoring element 33 in the base section 9 and a corresponding, but convex anchoring element 34 on the drive part 14. B. by gluing or soldering.
• the 14 shows two anchoring elements in the form of flat surfaces on the underside of the base section 9 or on the top of the transition section 16 of the drive part 14.
• the two anchoring parts are firmly connected to one another here along an interface 35 by welding.
• the front part 1 is provided with an anchoring element 36 in the form of a wedge rib projecting from the base section 9, while a drive part 37 is provided on its end face facing the base section 9 with an anchoring element 38 in the form of a corresponding, concave keyway.
• the two anchoring elements 36, 37 are fastened to one another by soldering along a solder seam 39.
• the exemplary embodiment according to FIG. 15 also differs from those according to FIGS. 7 to 14 in that the drive part 37 is cylindrical.
• FIG. 14 is connected to the front part 1 by welding along a weld seam 40.
• the cross section of the drive part 37 according to FIGS. 13 and 14 is somewhat larger than that of the base section 9 or as the diameter D1 in FIG. 2.
• 17 and 18 show a direct comparison of two screwdriver bits according to the invention, which differ in the area of a base section 9 and 41, respectively. While the base section 9 in FIG. 17 is configured as in FIGS. 1 to 9, the base section 41 has, in direct connection to an outlet 42, a radially widening zone 43 which then merges into a zone 44 corresponding to the base section 9.
• the embodiment according to FIG. 19 shown in direct comparison with FIGS. 17 and 18 differs from the embodiment examples according to FIGS.
• a drive part 45 is connected to a base section 47 of a front part 48 via a transition section 46.
• the base section 47 here has a dimension D1 (FIG. 2) which, in contrast to FIG. 7, is larger than the diameter of the hexagon section of the drive part 45, and the transition section 46 in this case serves to make the smaller cross section of the hexagon section with the larger one Cross section of the base portion 47 to connect.
• the anchoring elements 48 and 49 have a TORX profile analogous to FIG. 12.
• the connection of the two anchoring rod elements 48, 49 takes place, for. B. by soldering along a solder seam 50.
• a raised protruding anchoring element 52 is formed on the base section 9 of the front part 1 with a cross-shaped profile, which is inserted in a corresponding anchoring element 53 in the form of a cross slot which is formed in the upper end face of the transition section 16 of the drive part 14 ,
• the attachment is made, for. B. by gluing or soldering. This embodiment is currently considered the best variant of the anchoring elements.
• FIG. 25 shows an exemplary embodiment analogous to FIG. 17, in which a front part 1 a is provided with a penetration section 2 a with Pozidriv profile.
• a base section 9a is provided with a protruding anchoring element 12a which projects into a corresponding anchoring element 15a in the form of a recess which is machined into the upper end face of the transition section 16 of the drive part 14.
• the connection of the two anchoring elements 12a, 15a is carried out by soldering along a solder seam 54.
• LO is the length of the emrmg section 2a extending to a spout 8a
• L1 is the total length of the front portion la except for the length of the anchor rod 12a.
• Ll 2.5 • LO applies, preferably Ll ⁇ 2.2 • LO and with a very special advantage Ll ⁇ 2 • LO, LO being determined analogously to the description above.
• LO can also be selected equal to the dimension ET ⁇ x plus a small surcharge for tolerance compensation, since in this case the length LO would always be appropriate.
• the length of the anchoring elements should be as small as possible, so as not to impede the homogeneous distribution of pressure during the pressing process.
• the anchoring rod elements are arranged on the side of the front parts 1, la facing the press ram, their length is less critical than is the case for the lengths LO and Ll. Apart from this, it can be provided if necessary to include the anchoring elements in dimension L1.
• 26 to 28 show an embodiment of an insert for Phillips screws in which a front part 1b made of hard metal has no base part and no anchoring part.
• the crossbars continue cylindrical from length LO, the wall thickness, the core and the diameter of a crossbar profile 55 being retained as at point LO.
• the cross bar profile 55 is inserted in a corresponding recess 56 in the end face of the drive part 14 in a form-fitting manner and is expediently connected to it by soldering.
• the indentation sections have a cross-section that is uniform in the axial direction - slightly conical at Robertson.
• the profile preferably merges into a base part with a rounded outlet. This has the advantage that the cross section of the hard metal tip (the hard metal functional part) increases in the area in which the torsional forces become effective during use.
• the anchoring in the drive part is carried out in the same way as described in detail above.
• the minimum lengths LO of the Emdringa section are also specified by the manufacturer's standards or other regulations.
• B. have an associated data sheet. The functional lengths for the different profile sizes are derived from this if necessary with a surcharge.
• B. hexagon or Robertson profiles.
• the penetration sections with or without an outlet can merge into a base section corresponding to the outlet 8, 8a (for example FIGS. 1, 25), which usually runs along an arc.
• FIGS. 1, 25 for example FIGS. 1, 25
• the length L1 can be regarded as identical to the length LP, from which it follows that the ratio L1 / L0 in this case can be smaller than in the case of cross-slot front parts 1.1a, which have a comparatively large outlet 8.8a and thus have a comparatively large LP.
• the application of the invention to TORX and other profiles is explained in more detail below with reference to FIGS. 29 to 38.
• FIGS. 29 and 30, in analogy to FIGS. 1 and 2, show a front part 58 of a screwdriver insert according to the invention intended for TORX screws on a greatly enlarged scale.
• the front part 58 is arranged coaxially to a longitudinal or rotational axis 59 and is provided at its front end with an Emdringäb section 60, which has a conventional TORX profile, the undulating course of which results in particular from FIG. 30, and which penetrates into the corresponding inner profile a TORX screw.
• the TORX profile is characterized by webs 61 and grooves 62 (FIG. 30) with rounded edges which follow one another in the circumferential direction and are parallel to the axis 59 from which give the profile a wavy course along an imaginary circle.
• the TORX profile is the same in the entire sealing section 60 in the direction of the axis 59 and ends at a conical, flattened end section 63 which is insignificant for the purposes of the invention.
• the groove bases are from a point 64, the the rear end of the sealing section 60 defines, is curved radially outwards, as a result of which, analogously to the outlets 8, 8a, an outlet 65 is formed which ends at a base section 66 which essentially corresponds to the base section 9 according to FIG. 1 and has a rear end face 67 , which is generally perpendicular to axis 59.
• An anchoring element 68 in the form of a pin projects rearward from the end face 67 and has the same meaning as the anchoring element 12 according to FIG. 1. 29 and 30, the penetration section 60, the base section 66 and the anchoring rod element 68 are also arranged coaxially to the axis 59.
• the main part of the front part 58 essentially corresponds to that of the front part 1 according to FIG. 1, which is why for the purposes of the present invention the same lengths L0, Ll, LP and LB as well as the diameter D1 are assigned to it, as detailed above with reference to FIG was explained.
• a screwdriver insert for TORX screws according to FIG. 31 is assembled from the front part 58, which is produced separately and in one piece, and a drive part 69, likewise produced separately, which, for. B. in a section 70 has a conventional hexagon profile and is connected to the front part 58 by means of a transition section 71 analogous to FIGS. 1 to 30.
• the transition section 71 is provided with a corresponding anchoring element 72 in the form of a recess formed in its front end face.
• the connection of the two anchoring elements 68, 72 takes place analogously to the above description by gluing, welding, soldering or by other connection methods.
• the front part 58 is produced analogously to the cross-pointed front parts 1 from a hard metal powder and with the aid of a press tool according to FIGS. 8 and 9, the press bushing 20 and optionally the press die 23 being adapted accordingly.
• the dimension LO is again dimensioned as short as possible and preferably according to the penetration depths T that the provider of the respective TORX system specifies in a data sheet or the like.
• the length LO is preferably dimensioned at least equal to the predetermined penetration depth, with an addition being expediently added for tolerance compensation.
• the length L0 is z. B. to 2.40 mm, 2.50 mm, 3.50 mm, 3.65 mm and 5.05 mm and the length Ll to 4.1 mm, 4.8 mm, 5.8 mm, 6.95 mm and 8.35 mm are selected, in which case the Ll values are far below twice the L0 value. Very particularly preferred dimensions result from FIG. 39.
• Fig. 32 shows a screwdriver insert for screws with hexagonal inner profiles. This differs from the screwdriver insert according to FIGS. 29 to 31 only in that it has a front part 74 with an emdring section 75, which is provided with a conventional hexagonal profile. Otherwise, the different parts are the same, which is why the same parts with the same reference numerals as in FIGS. 29 to 31 are provided in FIG. 32.
• An outlet 1 is provided with the reference number 76.
• FIG. 33 shows a two-part screwdriver insert with a front part 77 having a Robertson profile, which has an indentation section 78 with a square profile designed in the manner of a square and seen from the top view.
• the front part 77 is connected along an arcuate radially outwardly curved outlet 79 to a base section which is provided on its rear side with the anchoring element 68, which is inserted into the anchoring element 72 designed as a recess of the drive part 69, which is preferably made of normal tool steel, and into this is attached. Since the arrangement is the same except in the sealing section 78 as in FIGS. 31 and 32, the same parts are again provided with the same reference numerals to simplify the illustration. It is clear that, for. B. the transition section 71 may have different shapes depending on the shape of the respective section 60, 75 or 78.
• Tungsten carbide which is designed as a TORX profile over its entire length.
• a drive part
• anchoring rod element 84 in the form of a concave recess, the inner cross section of which corresponds to the outer cross section of the front part 81.
• anchoring element 85 of the front part 81 the rear end portion is used here, the z. B. inserted into the anchoring element 84 and then firmly connected by gluing, pressing or soldering along a soldered seam to the transition section 83.
• FIGS. 37 and 38 show a further screwdriver insert which, in contrast to FIGS. 34 to 36, has a front part 87 which is designed continuously as a hexagonal profile.
• the transition section 83 as anchoring element 88 has a recess with an internal hexagonal profile in which the front part 87 with its rear end, which forms a further anchoring element 89.
• B. is fixed by soldering.
• the exemplary embodiments according to FIGS. 34 to 36 and FIGS. 37, 38 are distinguished from the other exemplary embodiments described in that the front parts 81, 87 have no outlet (e.g. 8 in FIG. 1) and no base part (e.g. 9 in Fig. 1).
• the length L1 of the front part 81 measured according to FIG. 2 actually corresponds to the length LO, since in this case the penetration section has a correspondingly dimensioned length over the entire length of the front part 81 due to the absence of the outlet Screw head opening could be inserted.
• the dimension L1 (FIG. 36) should again be chosen as small as possible.
• the maximum penetration depth T ⁇ x specified by the provider of the TORX or hexagon system or by someone else is assumed to be the penetration depth required to achieve an optimal torque transmission.
• this depth of penetration T MAX corresponds to the dimension T of the screw head 86, although the respective manufacturer usually specifies a dimension that is slightly larger or smaller than the dimension T in FIG. 36.
• the value L1 is then set at a maximum of 2.5 • LO and preferably at a maximum of 2.2 • LO. Ll ⁇ 2.0 • LO applies with particular advantage. It follows from this that the dimension LO is ultimately in all cases a variable which is determined by the system or by the prescribed or required penetration depth T, and that the dimension L1 need not be significantly greater than the penetration depth T here.
• the cross section of the front part 81, 87 is increased by approximately 0.1 to 0.2 mm in the region of the length LV.
• the front part 81, 87 can then be demolded without friction after ejection by the length LV, as a result of which the demolding process as a whole is facilitated.
• the two-part design described Compared to one-piece, e.g. B. manufactured by injection molding screwdriver inserts (z. B. DE 42 41 005 AI), the two-part design described has the advantage that the small front part made of hard metal is technically and dimensionally more precise and in the plane of the highest torsional stress, ie in the plane of the front end face of the drive part, has no notches which increase the risk of breakage due to the notch stress. As such notches z. B. the immediate transitions of the crossbars in the end face in the one-piece design according to DE 42 41 005 AI.
• ratio Ll / d (FIG. 2) should be approximately 1.0 to 1.2 in the case of cross-slotted profiles, i. H. Ll and dO should be about the same size.
• ratios L1 / dO (FIGS. 29, 30) of approximately 0.9 to 1.4 have proven to be expedient, i. H. here Ll can generally be slightly larger than dO.
• favorable ratios of L1 (FIG. 36) to dO are approximately 1.4 to 1.9, where dO is the corner dimension according to FIG. 38 in millimeters.
• Robertson profiles there are favorable front parts with Ll / dO (Fig. 33) of approx. 1.3 to 1.5, where dO is the corner dimension in millimeters (Fig. 33).
• the ratios length to diameter are expediently based on the total length LG according to FIG. 36.
• z. B. LG / dO be about 1.1 to 1.7.
• the smallest value for Ll / dO or LG / dO is determined by the respective size of Ll, whereby Ll cannot be less than L0.
• the invention is not limited to the exemplary embodiments described, which can be modified in many ways. This initially applies to the shape of the anchoring elements, whereby the use of two or more anchoring elements elements per bit would be conceivable if these z. B. would be formed as a very thin pin in cross section. Furthermore, the sizes LO, Ll, dO etc. described can be dimensioned differently than is specified above as an example. In particular, the length to diameter ratios should always be chosen so that the smallest possible circumferential or contact surfaces with the press tool result, so that favorable
• Friction and small ejector forces can be obtained. It is also possible not to use the absolute greatest depth of penetration for the dimensioning of LO. Rather, z. B. the largest T M ⁇ / T ⁇ N range used and the length LO selected so that it corresponds to a value that is approximately in the middle of this range. Then the penetration sections of the largest screws do not penetrate fully, but nevertheless penetrate deep enough into the recesses of the screw heads to achieve a good fit. Which dimensioning is particularly favorable in the individual case can easily be determined from the above explanations both by calculations and by tests. It turns out that the ratio L / dO should preferably be less than 2.2 throughout and preferably less than 2.0.
• the short length L1 or LG according to the invention is advantageous not only in the case of pressing and immediately following sintering, but also in the case of front parts produced by injection molding.
• demolding by means of an ejector is usually also desirable in injection molding, and it is therefore expedient to reduce the demolding resistance by reducing the length.
• a proportion of thermoplastic superplasticizer e.g. wax or plastic is added to the hard metal powder mixture, which is withdrawn from the blank before sintering.
• the selected grain size composition of the hard metal powder mixture has also proven to be important for the uniformity of the structural fracture of the inserts. Grain gradations in the mixture of 0.5 ⁇ m to 8 ⁇ m are particularly advantageous.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Joining Of Building Structures In Genera (AREA)
• Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
• Portable Nailing Machines And Staplers (AREA)
• Mutual Connection Of Rods And Tubes (AREA)
• Powder Metallurgy (AREA)
• Detergent Compositions (AREA)
• Burglar Alarm Systems (AREA)
• Control Of Stepping Motors (AREA)
• Dowels (AREA)
• Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7633331

Family Applications (1)

Country Status (7)

Families Citing this family (40)

Family Cites Families (20)

• 2001
  • 2001-03-06 EP EP01923507A patent/EP1175284B1/fr not_active Expired - Lifetime
  • 2001-03-06 WO PCT/DE2001/000852 patent/WO2001066312A1/fr active IP Right Grant
  • 2001-03-06 DE DE50110735T patent/DE50110735D1/de not_active Expired - Lifetime
  • 2001-03-06 ES ES01923507T patent/ES2270999T3/es not_active Expired - Lifetime
  • 2001-03-06 AU AU50276/01A patent/AU5027601A/en not_active Abandoned
  • 2001-03-06 AT AT01923507T patent/ATE336334T1/de not_active IP Right Cessation
  • 2001-03-06 DE DE10190814T patent/DE10190814D2/de not_active Expired - Fee Related
  • 2001-11-06 US US09/992,900 patent/US20020129680A1/en not_active Abandoned
• 2003
  • 2003-05-19 US US10/441,135 patent/US7168348B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events