ELE

The guillotine saw were composed of four parts which are the cut mechanism, spiral feed mechanism, mechanism of eccentric cam (used to lift the blade in backhaul) and chain fixing mechanism. 3D assembly of the guillotine saw was shown in Figure 2.2.

The guillotine saw could adapt to the cutting of 10 "-24" diameter pipe as well as rails and steel frames and so on within this scope of diameter. The guillotine saw could adapt to the different pipe by adjusting the length of the chain. The machine could be operated in vertical or horizontal state. It could be operated in water or on land. It could also cut the pressure pipe without the limit of conditions. It had a reliable performance. The material of pipes was high-strength steel for underwater oil&gas transporting. So the saw blade should had a good performance. It was chosen to be horniness alloy steel saw with staggered chamfering and back edge of 1 / 3 of the tooth width. A special saw blade also could be chosen to directly cut off the steel pipes coated with reinforced concrete, which studded

diamond particles on high-speed steel saw blade.

to the saw blade is heavy, it is necessary to drive the saw blade to move back and forth horizontally to achieve the cutting movement. In this paper, the transformation from the turn motion of the hydraulic motor to the linear motion of the saw blade is performed by sine mechanism. As was shown in Figure 3.1, transmission fork on the big gear can only move in the guided T-groove. When the big gear rotates, the tool carrier joined at the guided T-groove moves horizontally.

Fig.3.1 Principle of cutting movement

Movement analysis of mechanism was shown in Figure3.2. The rotation center of the big gear rotation acted as center of the coordinates. L1=50mm, LBC=295mm (the length of the tool carrier),

yC=

42mm,

1=4πα

rad/s,

α3B=-90º,

LBD=180mm (distance from the center of mass of the ABC pole

to B-point), α1is variable.

Fig.3.2 Movement analysis of cutting mechanism

3.1.1. Displacement equation

Fig.2.2 3D assembly of the guillotine saw

According to the geometric relationship in Figure 3.2, the

vector equation was established:

JJJKJJJKJJJKOA+AC=OC

III. KINEMATIC ANALYSIS

It was respectively established that the kinematic model of the cutting mechanism, feed mechanism, back cutter mechanism wiht the influence coefficient of sea current to the movement. We combined the four movement models and analyzed the composite movement. xC=xA+LBC=50cos4πt+295

3.1 Movement analysis of cutting mechanism

Transform the vector equation into the analytic form and

establish the displacement equation of transmission fork 2: xA=L1cosα1 x=50cos4πt (1)

A

yA=L1sinα1 yA=50sin4πt

The movement equation of slider C(the tool carrier):

yC=42

(2)

The function of the guillotine saw is making the damaged section of the underwater pipes successfully be removed. Owing

The coordinate of the center of mass of the ABC pole: