The handlebars of bicycles have many types, mainly divided into straight handlebars and horn handlebars. Compared with straight handlebars, horn handlebars are mainly composed of straight pipes and elbows. Riders holding elbows during riding can make the upper body pressure lower, so as to reduce wind resistance and facilitate long-distance riding; However, due to the reason that the rider holds the elbow and bends down his upper body, the connection between the straight pipe and the elbow needs to bear greater force, especially when driving on bumpy roads, the pressure on the connection between the straight pipe and the elbow increases sharply, resulting in the fracture of the horn handle.
In order to improve the bearing capacity of bicycle handlebars, seamless handlebars (sheep horn handlebars) have appeared in the market. By directly using bending equipment to bend both ends of the straight pipe, the purpose of seamless forming of the straight pipe and the elbow is achieved.
However, due to the differences in compressive strength and corrosion resistance of various metal materials, titanium pipes (titanium alloy pipes) are popular with manufacturers for their high compressive strength and good toughness. However, due to the great difficulty of bending titanium pipes, if they are directly bent by bending equipment, it is easy to cause titanium pipes to fracture and low yield; In addition, collapse and wrinkle may also occur in the process of bending treatment, resulting in the decline of the bearing capacity of the finished handlebars and poor quality.
A manufacturing method of bicycle handle, comprising a titanium tube bending process described in any one of claims 1-5, comprising the following steps:
1) . pipe shrinking treatment: adopt a titanium pipe with a diameter of D1, a wall thickness of B, and a length of H. use a pipe shrinking machine to compress both ends of the titanium pipe, so that the middle of the titanium pipe is formed into a vertical installation pipe with a diameter of D1 and a length of H1, and both ends of the titanium pipe are formed into a shrinkage pipe with a diameter of D2 and a length of H2; The wall thickness of the handle riser is equal to the wall thickness B of the two shrink tubes, and the handle riser is seamlessly connected with the two shrink tubes, and the transition radian at the connection is α； This process does not need heating treatment, and the titanium pipe after pipe shrinkage treatment is pickled as a whole according to step B;
2) First bend: install step C, put the pickled titanium tube into the heating equipment as a whole, and preheat the titanium tube at 500 ℃ for 5min; Then adjust the direction of the preheated titanium tube shrink tube and put it into the machine mold of the hydraulic press, start the hydraulic press according to the bending section modulus of the titanium tube to press and bend the shrink tube at both ends of the vertical installation tube, and in the process of pressing and bending the shrink tube by the hydraulic press, it is necessary to heat the shrink tube placed in the machine mold of the hydraulic press synchronously with a heating temperature of 700 ℃; In order to make the shrink tube form a relatively curved transverse grip tube and a first elbow, the first end of the transverse grip tube is connected with the handle vertical installation tube, and the second end is connected with the first elbow by bending, and the bending angle at the connection between the transverse grip tube and the first elbow is β， The bending radius is R1 and the bending arc length is La; The length of the horizontal grip tube is H1, the length of the first elbow is H2, and the length of the shrink tube h2 = H1 + H2 + La;
3) Second bend: remove the titanium tube after the first bend is processed, and preheat the first bend with a temperature of 500 ℃ and a duration of 5min according to step 2); Then adjust the direction of the preheated first elbow and put it into the machine mold of the pipe bender, and start the pipe bender to press and bend the first elbow. In the process of pressing and bending the first elbow by the pipe bender, it is necessary to synchronously heat the first elbow placed in the machine mold of the pipe bender with a heating temperature of 700 ℃; In order to make the first elbow form a radial grip tube and a curved brake mounting tube, the first end of the brake mounting tube is connected with the transverse grip tube, the second end is connected with the radial grip tube, and the bending angle of the brake mounting tube is δ， Bending radius R2, and the arc length of the brake mounting tube is LB; The length of the radial grip tube is LC, and the length of the first elbow h2 = lb+lc.
4) The third bend: continue to put the titanium tube processed in the second bend into the machine mold of the pipe bender, and preheat the radial grip tube with a temperature of 500 ℃ and a duration of 5min according to step 3); Then adjust the direction of the preheated radial grip tube and put it into the machine mold of the pipe bender, and start the pipe bender to press and bend the radial grip tube. During the bending of the radial grip tube by the pipe bender, it is necessary to synchronously heat the radial grip tube placed in the machine mold of the pipe bender with a heating temperature of 500 ℃, so that the bending angle of the radial grip tube is θ， The bending radius is R3.
5) Grinding: put the processed titanium pipe of the third bend into the mold of the heating equipment, and press the titanium pipe to adjust the left and right balance and grinding. So far, the bicycle handle is made and formed.
