CN87214769U - An extrusion die with low extruding torsion - Google Patents

Abstract

The utility model provides a screw thread extruding screw tap with low extruding torsion, and is characterized in that a direction of a spiral arrise and a direction of spiral of a screw thread are uniform, and thereby, the utility model is called equidirectional spiral arris extruding screw tap, comprising a lead part, an extrusion part, a calibration part, and a shank part. The extrusion part and the calibration part are longer than the general extruding screw taps, and thereby, the extruding torsion is decreased. The extruding screw taps of single-line and multiline trapezoidal, or rectangular and triangular internal screw threads which are designed by the structure can successfully extrude multiline trapezoidal or rectangular internal screw threads and metric internal screw threads.

Description

An extrusion die with low extruding torsion

The internal thread extrusion modling is a processing method with lot of advantages, and its effect is that machining can't rival.

The form of existing thread forming tap has triangular, four ribs, six ribs, eight ribs etc.The seamed edge direction has two kinds of straight trough and helicla flutes; The hand of spiral of scroll is opposite with the hand of spiral of screw thread, and scroll is vertical mutually with screw thread.This screw tap is made up of press section, calibration portion and shank.This thread forming tap is mainly used in the common metric thread of single line, and the moment of torsion that adds man-hour is 1～2 times of cut tap moment of torsion.For the darker trapezoidal or rectangular thread of tooth form profile, because lead angle is big, is difficult to reach according to the screw tap of the thread forming tap structural design of general processing metric system regular screw threads and gives the phase effect, very easily collapse tooth, even can't process.

The utility model provides a kind of extrusion torque less thread forming tap, and this screw tap is successfully used to process single line, multi-thread ladder type, square type and triangle internal thread.If be used for the thread forming tap of common metric thread, its characteristics will make the extrusion torque of extrusion process reduce greatly.

The structure of existing thread forming tap is developed by cut tap basically and comes.Some grooves are all arranged on the cut tap, and the purpose of groove is to form cutting edge and certain positive rake angle and chip removal.Groove has two kinds of straight trough and helicla flutes, generally all design to such an extent that the complementary angle of spiral fluted lead angle is equated with lead angle and direction opposite, i.e. what is called " incorgruous equivalence ".Helicla flute and screw thread are orthogonal, claim " incorgruous vertical " again.The advantage of this design is that the anterior angle of flank up and down equates.Axial force is little in working angles.If the helicla flute direction is identical with the hand of spiral of screw thread, will the two side rake differences up and down of same tooth be strengthened, following side rake is very big, and last side rake is very little, can't use at all.

Thread forming tap does not have cutting edge, no anterior angle problem, and thread forming is that the plastic deformation after being extruded by metal realizes.If the hand of helix of rib is identical with the helix of thread direction, will make screw tap screw-ins of taking advantage of a situation, reduced screwing interference and reaction force, eliminated the disadvantage of incorgruous vertical-type and straightedge type thread forming tap, and squeeze force is even, gets into and withdraws from rapidly, and is laborsaving.Give the discharge of taking advantage of a situation easily of dirt, chip in the hole, anti-detent plug is real, has improved the life-span and the extruding precision of screw tap.Therefore, for thread forming tap with the hand of spiral of scroll by equivalent in the same way or in the same way non-equivalence (equivalence or non-equivalence are meant that the complementary angle ω of the lead angle of rib equates with lead angle β or do not wait) design not only feasiblely, and can reduce the extrusion torque of extrusion process greatly.

For multi-thread trapezoidal or rectangle internal thread thread forming tap, scroll reduces the extrusion torque except that adopting in the same way, also need do some improvement on physical dimension, and particular content is as follows.

The multi-thread trapezoidal or rectangle design of scroll thread forming tap in the same way, referring to accompanying drawing, Fig. 1, Fig. 2, Fig. 3 are the trapezoidal thread thread forming tap.Fig. 4, Fig. 5, Fig. 6 are the rectangular thread thread forming tap.Fig. 1, Fig. 4 are front view, and Fig. 2, Fig. 5 are axial partial sectional view, and Fig. 3, Fig. 6 are the C-C sectional view.By front view as seen, screw tap is by guide portion La, press section Lb, and calibration portion also claims forming section Lc and shank Ld to form.Press section and calibration portion are the working portion of screw tap.Its cross section is similar to regular polygon.

One. the form of scroll in the same way:

1. equivalent in the same way type: β=ω, advantage is to be convenient to calculate, but manufacture difficulty is big.

2. non-equivalence type: β ≠ ω in the same way, in this case, ω must be less than β, otherwise can't make, and is untenable; The screw tap calculation of complex of this form, but handling ease is practical.

Two. the scroll number:

The scroll number must be the number of leads positive integer doubly, 1,2,3,4 ...Lift angle is big, and the line number is more, and the diameter smaller, selects less rib number; When lift angle less, when less or single line of line number and diameter are big, optional more rib number.It is 3,4,5,6,7,8 that general rib is counted Z ...

Three. screw tap each several part size computing method:

1. guide portion:

The guiding screw tap enters by crowded internal thread hole, and guide portion diameter d y is less than screw tap press section point diameter dq, and its length is less than or equal to by crowded reach.

2. press section:

Rib shape end face angle:

Advance bottom outlet for ease of dress cutter location and sword, prevent front end crash and damage the rib body, prevent deflection, protect press section.End face angle also play the guiding role when extruding.

Front end rib shape end face angle:

φa＝60°

The point diameter of press section should be less than the bottom diameter dq＜d1 of thread forming tap, and dq is a point diameter, and d1 is the bottom diameter of thread forming tap.And guarantee that front end can advance to be extruded 2/3 of internal thread total length by sword.

On the thread forming tap of general common metric thread, extruded length is (4～8) tooth number (through hole) or (2.5～4) tooth number (blind hole).Because trapezoidal thread or rectangular thread profile are dark, amount of compression is big, and is through hole.For multi start thread, the big more press section that also requires of helical pitch is long more.For extrusion torque is reduced, extruded length with 15～25 times of lead for well.

Lb＝（15～25）Tβ

For reducing the load of screw tap, big footpath, middle footpath, path can increase progressively extruding, prevent that extruding force is excessive and collapse tooth, and three of press section directly is positive taper thread.The thread form of thread form and calibration portion is similar figures.Big footpath with in, the angle of chamfer equivalence of path:

φc＝φb＝arctg（d－dq）／2Lb

Calibration portion is anti-taper thread; the pitch diameter of thread reduces 0.1mm by the peak of press section to the every 100mm of calibrating direction; thread plug is real and damage when preventing that screw tap from withdrawing from; and footpath wearing and tearing in the minimizing calibration portion; protection calibration portion; improve life-span and serviceability ratio, large, medium and small three footpath reverse taper values equate-3-

φd＝arc tg（0.1／100）·（1／2）

Existing thread forming tap is that every 100mm reduces by 0.03～0.05mm, and calibration minister degree is relevant with helical pitch, gets (5～10) helical pitch doubly and is advisable.

Lc＝（5～10）Tβ

The intersection point dislocation of the anti-taper thread intersection of the positive taper thread of press section and calibration portion, spiral shell square and helical pitch skew will cause the random tooth of screw thread, so the positive taper thread of press section and the anti-taper thread of calibration portion are connected naturally, do not have vestige, require the time processing moulding, must not be intermittently.4. shank: be the taper or the garden cylindricality that have the plane that is installed, the standard design of Morse cone is pressed in taper.

5. calculate in three footpaths:

(1) big directly computing formula:

Trapezoidal: d=d2+2ha+kz+2b/3

Rectangle: d=D+z+kz

Wherein in the d2-screw tap footpath

Ha-screw tap rib band portion crest height

The kz-bulk,

kz＝［d2－dz（1－δ）］·P／D（Dw－D）

＝d2δp／D（Dw－D）

Bulk and rebound value, the flow amount of contraction equates.

B-major diameter of thread tolerance

P-tooth distance

D-is squeezed root diameter

Dw-is squeezed the internal thread race diameter

Z-is squeezed the Bottom of Thread gap

δ-quilt squeezes the percentage elongation of material

(2) footpath in:

Trapezoidal thread: d2=D2+2b2/3+kz

D2-is squeezed footpath in the internal thread

B2-pitch diameter of thread tolerance

(3) path

Trapezoidal: d1max=D-2h-b1/3+kz

Or d1≤D1-b1/3+kz

Rectangle: d1≤D1-Z+kz

D1-thread forming tap bottom diameter

D1-is squeezed the internal thread path

B1-is squeezed internal thread path tolerance

6. rib depreciation k:

The rib depreciation k of the common metric thread that is provided in chief editors' such as Xiao Shigang screw tool one book can calculate by following two empirical equations:

K=(0.04～0.06) d or k=(0.6～0.7) p

To calculate this formula by following formula be general formula to the k value in the utility model

K＝（d／2）（1－Cos360°／2z）＋（Dm／2）｛1－Cos·Sin ^－1［（d／Dm）·Sin（360°／2Z）］｝

Under the bigger situation of emery wheel diameter,

K≈（d／2）（1－Cos360°／2z）

Under the situation of known taps rib number, diameter and the relief grinding angle of descent,

K＝（πd／2z）tgγd

The γ d-relief grinding angle of descent

Dm-emery wheel diameter

7. rib bandwidth

Rib bandwidth f is relevant with screw tap intensity with extrusion torque

D/360 ° of f=π d γ, when z=6, γ d=3～5 °

γ d-rib band central angle

The manufacturing of the thread forming tap of scroll in the same way provided by the utility model is the same with common thread forming tap, can obtain with grinding.

The extrusion torque of equivalence or non-equivalence thread forming tap is little in the same way, be specially adapted to single line, multi-thread trapezoidal or rectangle and triangle thread forming tap, this screw tap intensity is good, be difficult for collapsing tooth, wear-resisting durable, the life-span is long, the screw strength height that squeezes out, roughness can reach Ra1.6～0.8, the precision height, dimensionally stable, required extrusion equipment is simple, and engine lathe all can push, processing ease.

Claims (3)

1, the utility model is a kind of single line that is used to process, multi-thread trapezoidal, the thread forming tap of rectangle and triangle internal thread, also can be used for common metric thread, the front portion of screw tap is the press section of positive taper thread, it behind the press section calibration portion of anti-taper thread, excessively evenly the garden is sliding between press section and the calibration portion, naturally be connected, there is not vestige, be the shank that clamping is used at last, press section and calibration portion do not have cutting edge and chip area and have some extrusion edges, the hand of spiral that it is characterized in that extrusion edge is consistent with the hand of spiral of screw thread, the front end of press section has guide portion, the length of press section:

Lb=(15～25) T β, (T β is a lead),

Front end rib shape end face angle is 60 °, and point diameter is less, and screw tap can be advanced to be squeezed 2/3rds of internal thread total length by sword, and the tapering of calibration portion is bigger, and per 100 millimeters back taper amount is 0.1 millimeter, the rib depreciation:

K≈(d/2)(1-Cos360°/2Z)

2, thread forming tap according to claim 1 is characterized in that: the complementary angle of the lead angle of rib is less than or equal to lead angle.

3, thread forming tap according to claim 1 and 2 is characterized in that the diameter of guide portion is given the aperture, hole less than squeezing internal thread, and length is less than or equal to the length of being squeezed screw thread.

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