CN2486764Y

CN2486764Y - Self driving screw

Info

Publication number: CN2486764Y
Application number: CN 01246630
Authority: CN
Inventors: 许慰
Original assignee: Qiangli Hardware Co ltd Suzhou
Current assignee: Qiangli Hardware Co ltd Suzhou
Priority date: 2001-07-20
Filing date: 2001-07-20
Publication date: 2002-04-17
Anticipated expiration: 2011-07-20

Abstract

The utility model discloses a tapping screw which comprises a screw head, a screw tail, a screw, screw thread extending spirally on the periphery of the screw and a self tapping groove which is in the center of the screw head surface, and is characterized in that the screw thread extends along the screw to the screw tail according to a certain thread pitch and form a tail nose, and the terminal edge of the tail nose forms declining knife edge in the axial direction and the radial direction. By using the utility model screws can be screwed in the board surface and the wall surface of the foaming cement easily without hard sledding, and the screw can be screwed in effortlessly and has good withdraw resistance, furthermore, dusts produced in the screw-in process can be pressed in the space between the top of the screw tooth which reinforces the tightening effort.

Description

A kind of tapping screw

Invention field

The utility model belongs to a kind of tapping screw, particularly a kind of tapping screw that is applied on foam cement plate or the foam cement brick wall.

Technical background

The foam cement plate is a lightweight, and its quality is soft.Traditional mode is to hole with electric drill on foam cement plate (ALC plate) or foam cement brick wall, imbeds the injection moulding expansion bolt, with wood screw other objects is fixed again; Owing to be to allow the injection moulding expansion bolt in the hole of the inner wall smooth on the parent (ALC plate or foam cement brick wall), the expansion coefficient that screws in the back generation with wood screw reaches fixing purpose, therefore aspect the intensity, have on the durability suitable defective, particularly high-rise building equipment such as air-conditioning outer machine installed big hidden danger.

The purpose of this utility model is, that brings when using at above-mentioned swell fixture is not enough and inconvenient, proposes a kind of screw of architecture advances, and the afterbody of this screw adopts special tectonic, can be very easily and needn't be screwed into the plate face or the metope of foam cement arduously.

Another purpose of the present utility model is, the thread of this screw adopts non-symmetry structure, have when being screwed into leicht fallen D/A and good withdraw resistance is arranged, the powder that produces in the process of being screwed in addition can be pressed in the volume between the thread top by thread itself, strengthens fastening effect.

Summary of the invention

The utility model is to realize like this, a kind of tapping screw, comprise the screw thread that the helical of screw head, screw afterbody, screw rod, screw rod periphery extends and the well of screw head end face central authorities, it is characterized in that, described screw thread extends to the screw afterbody and forms the tail tip along screw rod, and described tail tip terminal edges axially and is radially forming the blade of inclination.

Description of drawings

Below in conjunction with accompanying drawing the utility model is further specified, the person skilled in art can have clearer understanding to structure of the present utility model, feature and advantage from following narration.

Fig. 1 is the profile schematic representation of the utility model tapping screw;

Fig. 2 is the local enlarged diagram of Fig. 1;

Fig. 3 is the worm's eye view of Fig. 2;

Fig. 4 provides the part sectioned view in the screw rod screw-in foam cement plate among Fig. 1.

Embodiment

See also Fig. 1, tapping screw 1 of the present utility model comprises the screw thread 5 that the helical of screw head 2, screw afterbody 3, screw rod 4, screw rod 4 peripheries extends and the well 6 of screw head 2 end face central authorities.Fig. 2 provides the partial enlarged drawing of screw afterbody 3, Fig. 3 is its worm's eye view, in conjunction with these two figure, be positioned at diverse location on the screw rod 4 according to screw thread 5, the screw thread branch can be the main 5a of portion of screw thread, extend to screw afterbody 3 according to certain pitch P and form screw thread guide portion 5b, and form screw thread tail tip 5c at the ending place of screw afterbody 3, the terminal edges of screw thread tail tip 5c axially and is radially forming the blade 7 of inclination.Fig. 4 provides this tapping screw and screws in the interior situation of cement board, F represents screw-in direction in the diagram, R represents to screw out direction, when tapping screw screwed in foam cement plate plate 13, blade 7 was at first cut in the foam cement plate 13, is entered in the foam cement plate 13 by screw thread tail tip 5c again, arrive screw thread guide portion 5b then, with certain pitch P entering part screw thread 5, in rotation, produce certain thrust, thereby screw afterbody 3 is entered in the foam cement plate 13 unobstructedly.After in screw afterbody 3 pierces foam cement plate 13, and then the main 5a of portion of screw thread enters in the foam cement plate 13, at this moment pierce in advance screw thread tail tip 5c in the foam cement plate 13 foam cement plate 13 in the less internal thread of tapping and by after extremely screw thread guide portion 5b expansion, be extended to screw thread 5 with certain pitch P by the main 5a of portion of screw thread again, form internal thread, whole process has no to damage to foam cement plate 13.

Dial-out power according to the R direction of tapping screw 1, transfer to direction thread face 9 will stop the dial-out of screw, if only consider the resistance of dial-out, the half of thread angle β of exit axis thread face 9 should be 0 °, but the dial-out power of this tapping screw 1 forms shearing to not destroyed foam cement plate 15 in foam cement plate 13, not only soft but also fragile foam cement plate hope is transferred to power and formed shearing and impacting force by the β angular dispersion.In this, half of thread angle β is set at 45 °, and the half of thread angle γ of approach axis thread face 8 is set at 21 °, and these two angles roughly have ± 1 ° mobility scale, dial-out power like this is dispersed into shearing and impacting force on the foam cement plate, can reach the effect that best prevention is transferred to.

Structural another main feature of the utility model is, as shown in Figure 4, the volume of supposing a screw 11 between the pitch P is V, and adjacent two thread tops 12 are C to the volume that forms at circumferencial direction between the screw rod tabular surface 10, and these two volume ratios satisfy C/V＞0.7.After screw 1 is screwed into foam cement plate 13 like this, shift to the periphery of screw 1 after crushed with the foam cement plate of screw 1 equal volume, the powder 14 of crushed foam cement plate 13 all is accommodated in the volume between the crest end.

In the example of Fig. 4, suppose the outer diameter D=8.15mm of screw, pitch P=4.50mm, thread rolling is processed rounded material and is formed thread, the diameter D1=5.97mm of the material before the thread rolling processing.Usually disregard axial mobile being left in the basket because of thread rolling processing, obtain thus calculating foregoing volume C and volume V according to following formula:

V＝π/4×5.97 ²×4.50＝125.90M ³

C＝π/4×8.15 ²×4.50-V＝108.74M ³

C/V calculates like this:

C/V＝108.74/125.90＝0.86(86％)

According to the pertinent regulations of JIS (JIS) to tapping screw, when the screw external diameter is 8.15mm, when pitch was 2.82mm, material diameter must be 6.35mm before the thread rolling, so just can calculate C/V.

V′＝π/4×6.35 ²×2.82＝89.26M ³

C′＝π/4×8.15 ²×2.82-V′＝57.78M ³

C′/V′＝57.78/89.26＝0.65(65％)

Standard C/the V=0.65 that promptly meets general tapping screw in the JIS of JIS.

The general shared volume averaging of foam cement plate bubble is about 75%, and only 25% is the cement solids thing, and wherein the diameter of bubble is 0.5mm.When on cement foamed plate, being screwed into screw like this, because of being screwed into, screw cause the material of the foam cement plate that is equivalent to the screw rod volume to be squeezed away, the material of this part is to crush bubble in the plate and be squeezed into volume C with 4 times density owing to screw is screwed into, be that the part bubble is also compacted in the ruined while between this field in the field between top, adjacent thread top.

In the example that Fig. 4 provides, the ratio of the volume C in zone is 100: 86 between the volume V of screw rod and adjacent thread crest, and the volume of the foam cement sheet material material that is not destroyed in the foam cement material in this zone volume is assumed to X, wherein has following relation:

X+4×(C-X)＝C+V

X＝C-V/3＝86-100/3＝53％

So just will cause 53% the material that is not destroyed to stop the dial-out of screw.As described in the institute of front, according to the regulation of JIS (JIS) to tapping screw,

V∶C＝100∶65

X=C '-V '/3=65-100/3=32 (%) does not have destroyed foam cement sheet material material to have only 32% like this, and fastening force is very high.By experiment, draw following table:

	C/V×100％	Withdraw resistance
	C/V×100％	Withdraw resistance	Trial target
1	86％	○	Trial target
1	86％	○	Trial target 2	74％	○
Trial target 3	70％	△	Trial target 2	74％	○
Trial target 3	70％	△	Trial target 4	55％	×
Trial target 5	51％	×	Trial target 4	55％	×
Trial target 5	51％	×	Zero good △ better * poor

The present technique field generally acknowledges, screw be in order to obtain sufficient fastening force, the volume C that the zone constitutes between the thread top reach screw rod volume V more than 70% for well.According to above-mentioned experimental result, adopt the tapping screw of the utility model structure, the C/V that obtains has reached 86%, has showed good effect aspect fastening.

The utility model is except being applicable to the foam cement plate or using on the body of wall that the foam cement brick makes, can also be used in the fixedly aspect of other building materials such as wood, steel, aluminium, plastics, or carry out that at exterior wall the installation of equipment such as air-conditioning outer machine for example or other are decorateed etc.

When using screw of the present utility model to shoot,, when the foam cement plate is cut, cause it to form screw cutting because the sharp-pointed front of screw combines with sharp thread; And when screw turns round, correspondingly the line style (spirality) according to thread advances, product pierces when beginning at screw, to the foam cement plate good incision is arranged and pierce and pierce after screw provide and be used for best self precession screw that fastening performance is arranged in the foam cement plate; Simultaneously, this product solved other screws pine, soft foam cement plate hollow revolves not tight problem.

More than all embodiments only for the explanation the utility model usefulness, but not to restriction of the present utility model, person skilled in the relevant technique, under the situation that does not break away from spirit and scope of the present utility model, can also make various conversion or variation, so all technological schemes that are equal to also should belong to category of the present utility model and should be limited by each claim.

Claims

1, a kind of tapping screw, comprise the screw thread that the helical of screw head, screw afterbody, screw rod, screw rod periphery extends and the well of screw head end face central authorities, it is characterized in that, described screw thread extends to the screw afterbody and forms the tail tip along screw rod, and described tail tip terminal edges axially and is radially forming the blade of inclination.

2, tapping screw according to claim 1, it is characterized in that, described screw thread is called approach axis thread face near a side of screw afterbody, described screw thread is called the direction thread face of transfering to away from screw afterbody one side, the thread form half-angle of described dial-out direction thread face is 45 ° ± 1 °, and the thread form half-angle of described approach axis thread face is 21 ° ± 1 °.

3, tapping screw according to claim 1 is characterized in that, described tapping screw satisfies:

C/V＞0.7

Wherein V represents the volume between the described screw unit pitch, and C represents the volume that adjacent two threaded tip form at circumferencial direction to described screw rod tabular surface therebetween.