Buckling type double-shaft-shoulder friction stir head

The invention discloses a buckling type double-shaft-shoulder friction stir head. The friction stir head comprises an upper shaft shoulder, a lower shaft shoulder and a stir needle. The upper shaft shoulder is fixedly connected with an upper shaft shoulder sleeve, and one end of the stir needle sequentially penetrates the upper shaft shoulder sleeve and the upper shaft shoulder to be connected with the lower shaft shoulder; a first key groove and a second key groove are formed in the two ends of the stir needle, an upper-position key groove is formed in the top end of the upper shaft shoulder sleeve, a lower-position key groove is formed in the bottom end of the lower shaft shoulder, and the upper-position key groove is communicated with the top end of the upper shaft shoulder sleeve; and the lower-position key groove is communicated with the bottom end of the lower shaft shoulder, upper-position keys are arranged in the first key groove and the upper-position key groove, and lower-position keys are arranged in the second key groove and the lower-position key groove. The buckling type double-shaft-shoulder friction stir head is convenient to mount and dismount, the length of the upper-position keys and the length of the lower-position keys are adjusted, therefore, the distance between the upper shaft shoulder and the lower shaft shoulder is changed, the antiknock characteristic is good.