Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23G—THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH
  • B23G7/00—Forming thread by means of tools similar both in form and in manner of use to thread-cutting tools, but without removing any material
  • B23G7/02—Tools for this purpose
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23G—THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH
  • B23G5/00—Thread-cutting tools; Die-heads
  • B23G5/02—Thread-cutting tools; Die-heads without means for adjustment
  • B23G5/06—Taps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23G—THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH
  • B23G2200/00—Details of threading tools
  • B23G2200/48—Spiral grooves, i.e. spiral flutes

Definitions

• the invention relates to an internally threaded tool, which can either be a chip-cutting tap or a non-cutting thread former.
• the tool is usually made of either high-speed steel or hard metal.
• the invention provides a method for producing a thread by means of the tool according to the invention.
• a tap is an internal thread cutting tool with a shank for clamping in a tool holder and with a thread cutting portion, which is made up of screw threads and is interrupted at the free end and consists of screw threads.
• guide or guide part which also consists of screw threads interrupted by flutes.
• this guide part does not perform any cutting work, but, as the name suggests, serves to guide and evenly advance the tap through the hole to be tapped.
• the tap Due to the existence of the guide part, the tap is thus self-propelling forwards, the tool carrier being set up in such a way that it easily accommodates the axial movement of the drill.
• the tool holder is usually provided with a compensating chuck.
• the guide part has certain disadvantages. This creates considerable friction between the tool and the thread that has already been cut. This leads to increased thermal and mechanical stress. This friction has a particularly negative effect at high cutting speeds.
• the guide part hinders the coolant supply to the gate area, where the cutting takes place. Thereby arises at the cutting point increased temperature and thus increased wear. In the case of deep threads, there are additional welding problems.
• the thread teeth of the guide part have to cut through irregularly running chips again, especially when machining long-chipping materials.
• blind hole taps also called blind hole taps
• through-hole taps the first case involves holes with a bottom that are open on one side
• the second case involves holes that are bottomless and open on two sides.
• the chips must be moved out of the hole, axially opposite to the thread cutting
• the flutes are helically shaped in the same direction as the direction of rotation of the drill, which means that they have a cutting effect.
• Thread formers In contrast to the tap, the thread former does not produce chips; it only deforms the material. Thread formers are also referred to as a "gate" and a guide part, although the term gate is strictly incorrect, since thread formers do not cut. For the sake of simplicity, however, this expression is also used here for the tapering front part, in which, just as with taps, the deformation work for the thread production is carried out. Furthermore, the guide part in thread formers has the same disadvantages as mentioned above with regard to taps. For example, In DE-A-2 414 635, a thread turret according to the
• 2 shows a blind hole tap according to the invention
• 3 shows a second embodiment of a blind hole tap according to the invention
• Fig. 6 shows a thread former according to the invention.
• a used blind hole tap comprises a shank 1 and a square 2, which is arranged on the shank 1 for the transmission of a torque in a chuck.
• the shaft carries a tapered neck 3 with a threaded head 4.
• the head 4 and the neck 3 are provided with, for example, three equidistant, helical flutes 5.
• the tool is usually with a conical tip 6, which has no function, but is only there for manufacturing reasons.
• the used tap (and also the used thread former) comprises a chamfer a and a guide part b.
• the bleed a tapers evenly towards the front. While the entire machining takes place in the gate area a, the guide part b only serves for the axial guidance of the tool in the thread that has already been produced. All taps and turrets are available. therefore after the State of the art on both the gate and the guide part.
• the length of the guide part is usually about 7 to 14 threads, with blind hole taps in the lower area and through taps in the upper area.
• the gate length is 1.5 to 6 threads.
• the well-known taps (and also thread formers) are used for both tapping in normal
• a blind hole tap according to the invention has a chamfer a but practically no guide part b.
• three threads 7 are formed behind the chamfer a in FIG. 2, they do not serve to guide the tool but merely form a reserve for possible regrinding.
• a possibly 0 Nachschleif sadness ensure the tool, the tools can Rushzugtechnisch a grout to three such threads underway. 7
• the service life of the tool improves on average by a factor of 2.
• chip evacuation is significantly improved with deep threads.
• the length of the threaded part after the gate (the 5 "regrinding reserve") never needs to be longer than 5 threads, preferably at most 3 (the ground teeth 8 and 10 in FIGS. 3 and 4 are not paid for).
• 3 shows a further embodiment according to the invention.
• three full threads 7 are provided for regrinding.
• a number of increasingly ground thread turns 8a, 8b, 8c, etc. are arranged axially behind the thread turns 7.
• a recess 9 is formed in the 5 direction of rotation in front of this row of increasingly truncated teeth 8, the diameter of which, like the neck 3, allows a certain amount of play with the thread already created.
• the thread core diameter is mainly the same along the entire thread head, including the cores between the ground 0 teeth 8.
• a number (for example 3 to 7) of heavily ground thread turns 10a, 10b, 10c, etc. is provided.
• the thread cores of these threads describe the same cylinder as the other 5 thread cores of the thread head.
• This thread core diameter is somewhat larger than the diameter of the neck 3.
• the thread tips of the thread already generated protrude Sanders somewhat in the grooves 11a, 11b, ll r, wir ⁇ between the abraded teeth 10 into which a secure '/) Soanbowung ensured.
• a chip clamping safely avoided between the thread already created and the tool.
• a tap of this type comprises a form-cutting groove 12 and a so-called dirt groove 13.
• this drill also comprises a threaded head with a mainly uniform core diameter and with a chamfer a.
• the regrinding reserve or "extra thread part” in this case comprises only one thread 7.
• FIG. 6 shows a thread former, which therefore produces threads in the workpiece without cutting. As with the taps, it is
• Thread core diameter slightly larger than the diameter of the neck 3 '.
• the tool can be formed with or without lubrication grooves 14.
• the tool shown has five full threads.
• the radial clearance angle in the thread flanks 15 is relatively small because of the axial guidance and to avoid radial fluctuations.
• the internal clearance angle in the thread of the M8 tap is approximately 0.15 °.
• a higher clearance angle leads to axial intersection of the tap (lack of guidance).
• the clearance angle ir be drastically raised.
• the tap according to the invention can Have clearance angles in the thread of over 0.5 °, preferably about 0.8 to 2 °, ie at least about five times the usual value.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)
• Drilling Tools (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20401736

Family Applications (1)

Country Status (2)

Cited By (3)

Citations (4)

• 1996
  • 1996-03-08 SE SE9600927A patent/SE9600927D0/sv unknown
• 1997
  • 1997-03-05 WO PCT/IB1997/000206 patent/WO1997032682A1/de active Application Filing

Patent Citations (4)

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