Background technique
Development along with the modern aerospace technology; Requirement to mechanical connection technology is more and more goed deep into, refinement; The extensive application of composite structure, multiple material overlaying structure has proposed requirements such as clear and definite light weight, high tenacity, long lifetime to employed interconnection technique.And titanium alloy material is low because of its density, characteristics such as specific strength is high, good corrosion resistance, is the ideal material of space flight and aviation with interconnection technique.Existing Aero-Space are mainly used regular screw threads, MJ screw thread and U.S. standard screw thread with the titanium alloy bolt, and it all is L ˊ≤2P (P representes pitch) that its screw-thread ending requires, and its transition zone is with the direct transformation of straight line angle.Screw-thread ending is meant the transition zone at the bottom of the product button complete thread last tooth, is lower than the bolt of 800MPa for strength grade, and screw-thread ending place intensity does not constitute influence to bolt.But strength grade is greater than the high-strength bolt of 800MPa, and screw-thread ending place Bottom of Thread, crest are concentrated the screw thread crackle intensity that causes because of break place stress and can be had a strong impact on the bulk strength of bolt, and product safety is constituted a threat to.Aero-Space use the tensile strength of titanium alloy high-strength bolt to be mostly 1100MPa, so screw-thread ending place structural relation is to the safety of integral device.
Summary of the invention
The purpose of the utility model is to solve the deficiency that above-mentioned prior art exists, and a kind of simple in structure, easy to process, titanium alloy short thread ending bolt that fatigue resistance is high is provided.
The utility model is realized through following technological scheme:
A kind of Aero-Space are with titanium alloy short thread ending bolt; Comprise bolt head 1 and bolt shank 3; Periphery, bolt shank top is processed with screw thread 5, and its specialization is the length L≤1.5P (P representes pitch) of screw-thread ending groove 4, because the screw-thread ending slot length is shorter; Can effectively eliminate crest and concentrate the screw thread crackle that causes, increase the fatigue resistance of bolt because of break place stress.
Said bolt head 1 forms under head fillet 2 with bolt shank 3 joints;
Said bolt head 1 is the countersunk head type of plush copper type or band tapering.
Said plush copper type bolt head is hexagonal head type, semicircle head dummy or plane plush copper type.
Said screw thread 5 is common metric thread, MJ screw thread, UNJ made in U.S.A or UN screw thread.
The beneficial effect of the utility model: since the screw-thread ending slot length of titanium alloy bolt from≤2P (P is a pitch) is reduced to≤1.5P, thereby the height of matching used nut also can reduce simultaneously with it, greatly reduces the weight of whole assembly system.The screw-thread ending structure of the utility model can significantly strengthen screw-thread ending place intensity; Eliminate Bottom of Thread, crest effectively because of the concentrated bolt fracture that causes of the stress that break caused; Improve the bolt fatigue resistance, and simple in structure, easy to process, using effect is good.
Description of drawings
Fig. 1: the utility model bolt head is the structural representation of hexagonal head type;
Fig. 2: the utility model bolt head is the structural representation of countersunk head type;
Fig. 3: be the utility model screw-thread ending position schematic representation;
Fig. 4: be prior art screw-thread ending position schematic representation;
Fig. 5: for the utility model short thread ending titanium alloy bolts and nuts cooperate schematic representation;
Fig. 6: for the prior art bolts and nuts cooperate schematic representation;
Among the figure: 1, bolt head, 2, under head fillet, 3, bolt shank, 4, the screw-thread ending groove, 5, screw thread.
Embodiment
Following with reference to accompanying drawing, provide the embodiment of the utility model, be used for the formation of the utility model is further specified.
Embodiment 1
A kind of Aero-Space of present embodiment shown in accompanying drawing 1, comprise bolt head 1 and bolt shank 3 with titanium alloy short thread ending bolt, and bolt head 1 forms under head fillet 2 with bolt shank 3 joints; Bolt head is a hexagonal head type, and the screw thread 5 of the peripheral processing in bolt shank top is common metric thread, and pitch P is 2mm; Screw-thread ending slot length L is 3mm; L≤1.5P, screw-thread ending position structure is shown in accompanying drawing 3, and d representes the screw thread path; C representes the imperfect tooth form diameter of thread, and D representes Major Diam.Because the screw-thread ending slot length is shorter, can effectively eliminate crest and concentrate the screw thread crackle that causes because of break place stress, increased the fatigue resistance of bolt.
Embodiment 2
A kind of Aero-Space of present embodiment shown in accompanying drawing 2, comprise bolt head 1 and bolt shank 3 with titanium alloy short thread ending bolt; Bolt head is the countersunk head type, and the screw thread 5 on the bolt shank is a UNJ screw thread made in U.S.A, and pitch P is 3mm; The ending slot length L of screw thread is 4mm, and L≤1.5P is because the screw-thread ending slot length is shorter; Can effectively eliminate crest and concentrate the screw thread crackle that causes, increase the fatigue resistance of bolt because of break place stress.