A combined cam shaft assembling method comprises the following steps: A, grinding the outer diameter of a steel pipe (2) to specified precision, and machining an inner hole of a cam sheet (1) and a signal disc to specified precision; B, pre-installing the cam sheet (1) and the signal disc onto the steel pipe (2) according to a specified sequence, distance and angle; C, utilizing a tension part (3) to penetrate through the steel pipe (2), ensuring the steel pipe (2) to be expanded, so as to fix the cam sheet (1) and the signal disc onto the steel pipe (2) and reach a specified torque. The method is carried out through a combined cam shaft assembling device. By adopting the tension part (3) to expand the steel pipe (2), the steel pipe (2) and the cam sheet (1) can be rapidly combined, the cam sheet (1) and the signal disc can be clamped onto the steel pipe (2) in a more reliable manner, and the strength of the entire cam shaft is relatively high.

A combined cam shaft assembling method comprises the following steps: A, grinding the outer diameter of a steel pipe (2) to specified precision, and machining an inner hole of a cam sheet (1) and a signal disc to specified precision; B, pre-installing the cam sheet (1) and the signal disc onto the steel pipe (2) according to a specified sequence, distance and angle; C, utilizing a tension part (3) to penetrate through the steel pipe (2), ensuring the steel pipe (2) to be expanded, so as to fix the cam sheet (1) and the signal disc onto the steel pipe (2) and reach a specified torque. The method is carried out through a combined cam shaft assembling device. By adopting the tension part (3) to expand the steel pipe (2), the steel pipe (2) and the cam sheet (1) can be rapidly combined, the cam sheet (1) and the signal disc can be clamped onto the steel pipe (2) in a more reliable manner, and the strength of the entire cam shaft is relatively high.

Disclosed is a pipe expanding punch for a drill, which is configured to expand a pipe by hitting the pipe by an anchor drill or a rechargeable drill. The pipe expanding punch includes: an expanding mandrel provided with at least one portion (hereinafter referred to as an expanding part) having an outer diameter larger than an inner diameter of a pipe to be expanded; and a holder formed integrally with the expanding mandrel and fixedly coupled to a drill such that the pipe is expanded using the drill, wherein the outer diameter of an introduction part of an end portion of the expanding mandrel is smaller than the inner diameter of the pipe, a first tapered step is provided between the introduction part and the expanding part, and at least one polished flat surface is formed by polishing the first tapered step.

Disclosed is a pipe expanding punch for a drill, which is configured to expand a pipe by hitting the pipe by an anchor drill or a rechargeable drill. The pipe expanding punch includes: an expanding mandrel provided with at least one portion (hereinafter referred to as an expanding part) having an outer diameter larger than an inner diameter of a pipe to be expanded; and a holder formed integrally with the expanding mandrel and fixedly coupled to a drill such that the pipe is expanded using the drill, wherein the outer diameter of an introduction part of an end portion of the expanding mandrel is smaller than the inner diameter of the pipe, a first tapered step is provided between the introduction part and the expanding part, and at least one polished flat surface is formed by polishing the first tapered step.

A combined cam shaft assembling method comprises the following steps: A, grinding the outer diameter of a steel pipe (2) to specified precision, and machining an inner hole of a cam sheet (1) and a signal disc to specified precision; B, pre-installing the cam sheet (1) and the signal disc onto the steel pipe (2) according to a specified sequence, distance and angle; C, utilizing a tension part (3) to penetrate through the steel pipe (2), ensuring the steel pipe (2) to be expanded, so as to fix the cam sheet (1) and the signal disc onto the steel pipe (2) and reach a specified torque. The method is carried out through a combined cam shaft assembling device. By adopting the tension part (3) to expand the steel pipe (2), the steel pipe (2) and the cam sheet (1) can be rapidly combined, the cam sheet (1) and the signal disc can be clamped onto the steel pipe (2) in a more reliable manner, and the strength of the entire cam shaft is relatively high.