EP0675782A1

EP0675782A1 - Tool.

Info

Publication number: EP0675782A1
Application number: EP94903753A
Authority: EP
Inventors: Martin Strauch; Robert Hoy
Original assignee: Wera Werk Hermann Werner GmbH and Co KG
Current assignee: Wera Werk Hermann Werner GmbH and Co KG
Priority date: 1992-12-22
Filing date: 1993-12-10
Publication date: 1995-10-11
Anticipated expiration: 2013-12-10
Also published as: JPH08504685A; US5704261A; DE59307519D1; WO1994014575A1; AU5809894A; EP0675782B1; DE4243608A1; DE4243608C2

Abstract

The invention relates to a tool, especially a torque transmission tool like a screwdriver or screwdriver insert with a shaft and a working region. In order to be able advantageously to absorb torque peaks with such a tool, in the shaft there is a damping region of reduced hardness or lower torque-rod constant than the working region. To this end the damping region can be subsequently annealed or have a different material composition. The latter is preferred in a sintered metal tool.

Description

00001 WERKSEÜG, ESPECIALLY SCREWDRIVER INSERT ******************************************

00002

00003 The invention relates to a tool, in particular a torque

00004 ment transfer tool, preferably screwdriver or

00005 screwdriver bit, with a shaft and a

00006 drive range according to the preamble of claim 1 and

00007 a method for producing such tools- 00008

00009 A generic screwdriver bit is

00010 from European patent application 0 336 136

00011 known. With the screwdriver insert disclosed there

00012 a torsion zone is provided in the shaft area.

00013 This twistable intermediate section constitutes an

00014 flexible element with corresponding reset

Assets after overcoming the peak load. He

00016 endures bigger moments, even with repeated ones

00017 load. The intermediate section acts as a damper, so

00018 that torque peaks are not directly proportional to

00019 screwdriver tip section take effect- In particular-

00020 special if with such screwdriver bits

00021 machine screwed screws in metal thread

00022, there are considerable torques

00023 ment peaks, since the speed of the drive motor will soon

00024 ster time must drop to zero. This period of time will

00025 extended by the elasticity of the torsion section,

00026 so that the torque load is reduced overall

00027 will. With regard to the further advantages of such a

00028 gene torsion section is also on DE 38 07 972

00029 referenced. With the screwdriver disclosed there

00030 sets the torsion zone b ° i a tool ~ <i "i

00031 uniform material properties through a special

00032 le geometrical formation of this shaft area

00033 forms. This is essentially done by a Uuei -

00034 weakening in this area. 00035 The invention has for its object in one

00037 generic tool the damping zone advantageous

Further training. 00039

00040 The object is achieved by the

00041 ne invention and that specified in claim 10 to 12

00042 manufacturing process. 00043

00044 The subclaims represent advantageous further developments

00045 of the invention. 00046

According to the invention, there is a tool in which

00048 the different torsibility or hardness or

00049 material strength of tip and shaft section not

00050 necessarily achieved by the shape of the tool

00051, but rather through different specific

00052 see properties of the material from which the tool is made

00053 is made. According to the invention it is provided that the

00054 damping zone has a material that has a low

00055 higher hardness or what is the same, a lower

00056 has material strength. But it is also planned

00057 that this damping range has a lower torsional

00058 constant than the work area can have.

00059 Finally, it is also envisaged that the

00060 see damping area both a lower torsional

00061 spring constant as well as a lower material

00062 speed. During the output range, which at

00063 a screwdriver bit from the screwdriver

00064 ze is made of a material which

00065 a high torsion spring constant or high hardness

00066, the twistable shaft section is made of one

00067 made of material that has a lower torsion spring

00068 constant or low torsion spring constant.

00069 The damping zone consists of a material which

00070 is softer than the work area, i.e. a smaller one 00071 has strength, it can nevertheless be provided

00072 that the modulus of elasticity in both shaft sections

00073 is identical or almost identical. The zone softer

00074 material or lower strength is then, however

00075 plastically deformable to a greater extent than the working

00076 rich. If the screwdriver suddenly stops

00077 tools, the rotational energy of the screwdriver

00078 ges in the plastic deformation of the shaft section

Include 00079. The hardness of this damping zone is preferred

00080 so far reduced that a plastic deformation of

00081 30 to 60 is possible without the tool breaking.

00082 Especially with small plastic deformation angles

00083 of 30 ° is provided that after an inevitable

00084 elastic reset by a few degrees again plastic

00085 see deformations around larger amounts are possible without

00086 that the screwing tool breaks. Wise according to a

00087 preferred design the shaft areas different

00088 elasticity modules, is an undesirable twistable

00089 speed of the output area avoided, but the

00090 desired torsion (elasticity) of the shaft ab-

00091 section of the damping zone achieved. 00092

00093 According to the preferred further development, the shaft section has a material of lower hardness than the section.

00095 drive area. This measure differentiates

00096 before the deformability of the two areas is achieved.

The hardness (Rockwell) of the shaft section is up to

00098 about a quarter less than the hardness of the output

00099 area. The shaft section is preferably

00100 telbar adjacent to the output area. That is, the

00101 The tip of a screwdriver bit closes

00102 immediately a plastically deformable shaft section

00103, which then, for example, in a drive area

00104 can pass, which is polygonal in cross section

00105 is and again made of a harder material 00106 hen. The shaft section that has the lower strength

00107 speed can be achieved by subsequent tempering (heating

00108 men) of a pre-hardened tool.

00109 The tool can then be produced using the same material. 00110

00111 In a further preferred embodiment of the tool

00112 the tool consists of two different sintered materials

00113 rialien, preferably steels, the output range

00114 made of a harder material and the shaft section

00115 is a softer material. The softer material

00116 of the shaft section can also be in the

00117 Continue output area and there a core area

00118 who is certain of a harder sintered material

00119 is encased. This casing forms

00120 the working tip of the tool. Through this measure

00121 e is a continuous change in strength from

00122 shaft section given to the output area. The two

00123 sintered materials can differ due to their grain size

00124 or differentiate by their material composition.

00125 It is essential, however, that in the sintered state,

00126 So in the finished tool zones with different

00127 Form spring characteristic. In this made of sintered metal

00128 manufactured tool is particularly provided that

00129 a shaft section made of a material with a low

00130 Ren modulus of elasticity is made, so that here

00131 lower torsion spring constant is achieved. 00132

According to the manufacturing process it is provided that at

00134 pre-hardened tool at least one shaft area

00135 of the shaft is tempered to a temperature. at

00136 which is a softening of the material, which preferably consists of

00137 steel or a steel alloy, takes place.

00138 The output area is cooled, around whose material

00139 to obtain properties. The starting happens

00140 such that the heated shaft section a 00141 gets blue coloring. Through this tempering the

00142 shaft section preferably heated up to the core area

00143 and then continuously receives a different material structure

00144 with a lower strength. Because of that when starting

00145 emerging temperature gradients to the cooled area

00146 a continuous strength transition is achieved.

00147 Because of the heat penetration from the surface, can

00148 the temperature reached in the core area may be lower

00149 as the temperature at the surface, what regarding

00150 a continuous hardness transition as advantageous

00151 is viewed. The heating is preferably done by

00152 an inductive heating. The tool comes with

00153 the shaft section to be heated in an induction coil

00154 le held. Both sides are preferred

00155 shank section adjoining tool areas

00156 a liquid application cooled, so that only

00157 the intermediate section the desired material softening

00158 experiences. The application of liquid can

00159 Weil consist of a water shower. 00160

00161 The method for producing a sintered tool

00162 ges provides that first a shaft forming

00163 blank is molded from softer sintered material,

00164 which then the output area made of harder material

00165 is molded. This two-component raw

00166 ling is then used for solidification in a known manner

00167 heat applied. The blank can be injection molded

00168 sen and made of globular sintered material with a

00169 grain size of 10-15 μ exist. Can be used as a binder

00170 a plastic must be added to the metal powder

00171 injection molding can be known from plastics technology

00172 procedures are applied. During the sintering process,

00173 the heating of the workpiece in an oven on the

00174 required sintering temperature of 1,200, for example

00175 Celsius, the binder escapes from the blank. By 00176 additional pressurization finds compression

00177 of the workpiece instead, possibly also shrinkage. 00178

00179 Two embodiments of the invention are described below.

00180 fertilized explained with reference to Figures 1-4. It shows: 00181

00182 Fig. 1 shows a machine screwdriver bit

00183 of a first embodiment, 00184

00185 FIG. 2 shows the hardness curve in a tool according to FIG. 1, 00186

00187 Fig. 3 is a schematic representation of a tool

00188 of FIG. 1 in the manufacturing process, and 00189

4 shows a cross section through a tool of the two-

00191 th embodiment. 00192

00193 The tools shown in Figures 1-4 are

00194 screwdriver bits according to DIN standard. You instruct

00195 drive end, which has a hexagonal cross section

00196 is formed and a shaft section which in

00197 cross section is round and one in cross section

00198 cross-shaped working tip, which for engagement in a

00199 Phillips screw is suitable. With regard to the

00200 closer design features of the embodiments

00201 in particular like the dimensioning of the individual areas

00202 before can be trained on the European

00203 patent application 0 336 136. The material of the

00204 tool according to the invention has in its extension

00205 direction (axis) an inhomogeneous spring characteristic

00206 history. 00207

In the first embodiment (Fig. 1) there is

00209 Tool made from a material and

00210 hardened steel body, the shaft area 4 subsequently 00211 borrowed by applying heat in its hardness or

00212 strength has been changed. Output range 2 and

00213 drive area 3, however, are not in their hardness or

00214 strength has been changed. The measured in degrees of hardness

00215 course of the strength of that shown in Fig. 1

00216 screwdriver bit 1 is shown in Fig. 2.

00217 There it can be seen in particular that the output

00218 rich I, that of the cross-shaped in cross section

00219 insertion tip 2 is formed, a higher hardness or

00220 has strength than the shaft portion II that of

00221 the substantially cylindrical shaft 4

00222 det. The diameter of the shaft 4 is

00223 example less than the largest cross-sectional

00224 extension of the cruciform output tip 2. The

00225 drive area III, which is of a six-

00226 angular cylinder 3 is formed, the diameter

00227 is larger than the shaft 4, has the hardness or strength

00228 speed of the output range I, which is higher than that

00229 hardness or strength of the shaft section II- 00230

00231 The hardness transition of the output area I in the shaft

00232 section II and the hardness transition from the drive

00233 cut III in the shaft section II does not take place

00234 erratic but continuous. 00235

00236 In Figure 3, the method for manufacturing is schematic

00237 of a screwdriver bit of the first embodiment

00238 form shown. To the material structure of the shaft

00239 section II to be changed so that its spring characteristics

00240 never gets smaller, this shaft section II is through

00241 heat applied. For this purpose, the shaft section 4 in

00242 introduced an induction coil 5, which then with

00243 current is applied. Due to the eddy current formation in

00244 shaft 4, heat is generated there which changes the structure.

00245 tion causes. The application of heat is preferred 00246 until the surface of the shaft 4 is blue

00247 has accepted color. So that the material structure of the

00248 output tip 2 and the drive area 3 not

00249 dert, the tip 2 and the hexagonal section 3 with

00250 a coolant K applied. This can get in the way

00251 a shower-like water application happen. 00252

00253 After such a treatment of the tool is on

00254 the working tip has a strength of 63 HRC (Rockwell

00255 hardness) and on the shaft 4 a strength of 45 HRC (rock

00256 hardness) measured. The shaft of one treated in this way

00257 tool can be turned more than the hardened

00258 te tip 2 or the hexagonal section 3 allows, whereby

00259 with the stronger rotation a plastic deformation

00260 goes along, depending on the reduction in strength 30 ^°

00261 to 60 can be. The zone can not only

00262 once, but several times plastically deformed without 00263 that the value of a maximum torque at which the

00264 plastic deformation begins, changes significantly.

00265 If you load a screwdriver manufactured in this way

00266 bit with increasing torque, this is done first

00267 an elastic deformation of the tool. After over

00268 If a limit torque is exceeded, a plastic

00269 see deformation. After completing the plastic deformation

00270 mung turns the rotated tool only around the elastic

00271 see the angular amount back again. 00272

00273 The screwdriver bit shown in FIG.

00274 consists of a cross-shaped tip 12,

00275 which forms the output area I and a m eseni-

00276 lent cylindrical shaft 14, the

00277 forms shaft section II and a hexagon tab

00278 cut, which forms the drive area III. The

00279 shank 14 has a smaller diameter

00280 as the maximum diameter of the hexagon section 1 ' 00281 and the working tip 12 of the screwdriver bit

00282 11. The screwdriver bit 11 consists essentially of

00283 chen made of a softer sintered material W

00284 existing core and a training tip 12

00285 the jacket made of harder sintered material H. 00286

00287 hexagon area 13 and shaft 14 are in this embodiment

00288 example of the softer sintered material w,

00289 zen therefore has a lower torsion spring constant than

00290 the tip 12. To achieve a continuous

00291 hardness transition or spring constant transition is the

00292 core area 15 of working tip 12 made of softer sintered

00293 material W. The actual work tip

00294, on the other hand, is made of harder sintered material H

00295 forms, which extends like a jacket over the core.

00296 A particular advantage of making tools from

00297 sintered materials is that the individual

00298 shaft areas made of different materials or

00299 material compositions can be manufactured. Here-

00300 to it is even possible to the individual switch areas

00301 to give different elasticity modules. hereby

00302 is not just an intervention in the hardness curve or

00303 strength course possible. The specific

00304 fish spring constant over the length of the tool

Set 00305. 00306

00307 To manufacture such a screwdriver insert

00308 zes 11 is first the hexagon section 13 and

00309 the shaft 14 and the core 15 forming blank

00310 soft sintered material W pre-pressed (injection-molded) -

00311 This blank is then made from harder sintered material

00312 al H existing tip 12 molded (injection molded),

00313 which is essentially a cross-shaped cross section

00314. This Rohlinq consisting of two components

00315 is then subjected to heat build-up in a known manner 00316 solidified. The different sintered materials W

00317 and H can differ with regard to their composition and

00318 differentiate their grain size. A grain size is preferred

00319 large from 10-15 microns for the harder area

00320 selected. In addition to metallic components

00321 the sinter powder also plastic components as

00322 have binders. With the finished screwdriver

00323 set, the shaft 14 has a greater twistability

00324 or firmness as the cross-shaped working tip

00325 12. The hardness of the working tip 12 can range

00326 are between 60 and 63 HRC and the hardness of the shaft

00327 14 be about 50 HRC. 00328

00329 A method according to the German

00330 patent specification 39 07 022 can be selected. 00331

00332 A metal powder injection molding process is suitable for

00333 powder metallic production of small parts. The

00334 method is derived from the known plastic fuel

00335 zen, the plastic 50-70 volume percent metal

00336 powder can be added. The resulting flowable

00337 hige mass is pressed to said green compacts. In front

00338 the actual metal powder injection molding is the metal

00339 powder with a binder, which contains plastic components 00340, in a certain volume ratio of

00341 for example 70:30 with reduced inert gas pressure and approx.

00342 150-180 Celsius mixed together. The volume ratio is determined by the grain size

00344 injection molding machine, the mass at 150-200 ^° and at

00345 slowly scoring a pressure of 150 bar into a mold.

00346 The different components can either

00347 simultaneously (multi-component injection molding) or one after the other

00348 of different forms or the same forms

00349 are injected. The binder can be removed in two stages

00350. In a first step, the green compacts can 00351 a solvent can be immersed, part of the

00352 binder is removed so that a spongy open

00353 Porosity arises, which runs through the entire component.

00354 The second binder removal can then be carried out in the sintering furnace

00355 take place together with the actual sintering process.

00356 The delivery phase is preferably in the phase in

00357 which the furnace is heated up. It can be in the oven

00358 an increased pressure from a mixture of argon and water

00359 serstoff be set. Simultaneously with the delivery

00360 fertilize the powder particles begin to mix

00361 tern. This happens around a temperature of 800

00362 Celsius. Then there is already a mechanically stable one

00363 sintered body. The furnace is then placed on the sintering

00364 temperature of about 1,200 Celsius and the oven

00365 is evacuated. If the the initially open porosity

00366 has completely closed, the pressure in the oven can

00367 can be increased up to 100 bar to ensure complete

00368 to achieve sealing of the component. As powder material

00369 are globular particles with a grain size of 10-15 μm.

00370 hen. The chemical composition (alloy) is

00371 according to the intended hardness (spring characteristic) of the

00372 material selected. When molding the green compacts

00373 can use a mold with a variety of mold nests

00374 find fertilizer. 00375

00376 The in the above description, the drawing and

Features of the invention disclosed in the claims can

00378 both individually and in any combination for

00379 the realization of the invention may be of importance.

00380 All disclosed features are inventive + l eh- In

00381 the disclosure of the application is hereby also the

00382 Disclosure content of the associated / attached priori -

00383 full documents (copy of the pre-registration)

00384 borrowed included.

Claims

00385 A N S P R Ü C H E 00386

00387 1st tool, in particular torque transmission

00388 stuff, preferably screwdriver or screwdriver

00389 set, with a shaft and a work area, thereby

00390 characterized in that the shaft (4, 14) at least one

00391 shaft section (II) has a lower hardness

00392 as the work area (I). 00393

00394 2nd tool, in particular torque transmission

00395 stuff, preferably screwdriver or screwdriver

00396 set with a shaft and a work area, in particular

00397 dere according to claim 1, characterized in that the

00398 shaft (4, 14) at least one shaft section (II)

00399 has a lower torsion spring constant

00400 as the work area (I). 00401

00402 3. Tool after or in particular after one or more

00403 ren of the preceding claims, characterized

00404 net that the hardness of the shaft end measured in Rockwell

00405 section (II) is up to about a quarter less

00406 as the hardness of the work area (I). 00407

00408 4. Tool after or in particular after one or more

00409 ren of the preceding claims, characterized

00410 that the shaft section (II) directly

00411 beitsbereich (I) is adjacent. 00412

00413 5. Tool after or in particular after one or more

00414 ren of the preceding claims, characterized thereby

00415 net that the area of lower hardness and / or lower

00416 rer spring constant between a drive range h (III)

00417 and a work area (I) is arranged. 00418 00419 6. Tool after or especially after one or honorary

00420 ren of the preceding claims, characterized

00421 net that the material hardness of the work area (I)

00422 molded-on shaft section (II)

00423 by subsequent tempering of the hardened tool

00424 (1) is lowered. 00425

00426 7. Tool after or especially after one or honorary

00427 ren of the preceding claims, characterized

00428 net that the shaft section (II) has a drive

00429 rich (III) with a higher torsion spring constant

00430 and / or hardness. 00431

00432 8. Tool in particular according to claims 1-4, characterized

00433 characterized in that output area (I) and shaft section (II) from two different sintered materials,

00435 preferably consist of sintered steels, the output

00436 rich from a harder material (H) and the shaft

00437 cut (II) consist of a softer material (W), 00438 where the output area consists of a harder area (H) 00439 or a material with a higher modulus of elasticity and

00440 the shaft area (II) made of a softer material (B)

00441 or a material with a lower modulus of elasticity

00442 hen. 00443

00444 9. Tool, in particular according to claim 7, thereby

00445 indicates that the output area (I) in the transition area

00446 submit to the shaft section (II) in the core area (15)

00447 Sintered material of lower hardness (W) or less

00448 has elastic modulus. 00449

00450 10. Manufacturing process for a tool according to or

00451 in particular according to one of claims 1-6,

00452 indicates that with the pre-hardened tool at least

00453 ens a shaft section (II) of the shaft (4) on a 00454 temperature is started at which a softening of the

00455 material, preferably steel, takes place during the

00456 work area (II) is cooled. 00457

00458 11. The method in particular according to claim 9, characterized in 00459 that the heating takes place inductively. 00460

00461 12. The method in particular according to claim 9, characterized by

00462 indicates that the working area (I) and the arrival

00463 drive area (III) which divides the shaft section (II)

00464 see themselves absorbing liquid

00465 can be cooled. 00466

00467 13. Method for producing a tool, in particular

00468 others according to claims 7 and 8, characterized

00469 net that the soft sintered material (W) or sintered

00470 preformed material with lower modulus of elasticity

00471 shaft (14) a work area (12) made of harder sintered

00472 material (H) or material with a higher modulus of elasticity

00473 is molded and this consists of two components

00474 en blank is hardened for solidification. 00475

00476 14. Tool after or especially after one or

00477 several of the preceding claims, characterized

00478 shows that the shaft area (II) of lower hardness

00479 plastically deforms when a torque lying above an upper limit torque is applied. 00481

00482 15. Tool after or in particular after one or

00483 several of the preceding claims, thereby

00484 shows that the plastic deformability is an independent

00485 very unique, preferably repeated overturning of the

00486 shaft section (II) by at least 30 ^° , preferably 40,

00487 50 or 60 without weakening the tool

00488 allows. 00489 16. Tool after or in particular after one or

00490 several of the preceding claims, characterized

00491 shows that the limit torque at which a

00492 plastic deformability occurs after a first

00493 plastic deformation essentially unchanged

00494 remains.