OLSEN REIDAR OTTO (NO)
| US4249346A | 1981-02-10 | |||
| GB2016321A | 1979-09-26 | |||
| US5566437A | 1996-10-22 | |||
| GB1576193A | 1980-10-01 |
C L A I M S
1. Tool (20) for cutting and grinding of welds on doubling plates in offshore environments where there is a danger of explosion, c h a r a c t e r i s e d by comprising: at least one end support (22a, 22b) with corner legs (26) on wheels, a magnet (28) that can be activated for clamping of the tool (20) to a base, an adjustable arm (30) with a cutting or grinding disc (32), where the arm (30) is arranged to be moved between predetermined points on a longitudinal glide rail (24) by a motor-driven spindle (34), where the glide rail (24) is arranged between said end supports (22a, 22b), a control cabinet (36) for control and supply of air to the tool, and a control cabinet (38) for control and supply of water to the tool, whereby the longitudinal movement of the arm and the adjustment to the cutting or grinding area is arranged to be controlled by air, while the cutting or grinding disc (32) is arranged to be driven by air and cooled by water.
2. Tool (20) according to claim 1, c h a r a c t e r i s e d i n that the spindle (34) is driven by an air motor (Ml, M2) at one or both ends, and that a clutch (40), which is placed between the air motor (Ml, M2 ) and the spindle (34), is activated by a number of air cylinders (C2, C3, C4, C5) .
3. Tool according to claim 1, c h a r a c t e r i s e d i n that the longitudinal movement on the glide rail (24) of the arm (30) is controlled by contact switches (Kl, K2), which are movable and attachable.
4. Tool according to claim 1, c h a r a c t e r i s e d i n that the arm (30) is secured to a cross-wise slide.
5. Tool according to claim 1, c h a r a c t e r i s e d i n that the arm (30) comprises appliances for supply of water to the cutting or grinding disc (32), arranged to ensure that the temperature of the working area is held below a predetermined limit value.
6. Tool according to claim 5, c h a r a c t e r i s e d i n that the temperature is arranged to be held below 80 0 C, preferably below 65 0 C. |
Tool for cutting and grinding in EX environment.
The present invention relates to a tool for cutting and grinding of welds on doubling plates in offshore environments where there is a danger of explosion.
From prior art, reference is made to JP 62139653 which relates to a device for grinding of a weld seam with the help of a removable frame. GB 2,016,321 relates to a machine for grinding rails which is moved on a wheel- supported wagon that can be driven along the rails.
In EX environments, i.e. environments where there is a danger of explosion there are, on offshore installations, special reguirements which must be met, which are, for one thing, regulated in the EU directive ATEX 94/9. The present invention is designed to satisfy these requirements .
Consequently, it is an object to provide a tool for cutting and grinding in offshore environments where there is a danger of explosions.
None of the abovementioned known documents refers to grinding equipment which is driven by air and which is cooled by water to avoid explosions during work in environments where there is a risk for explosions.
Said object is achieved with a tool that is defined in the independent claim 1, in that the tool comprises: at least one end support with corner legs on wheels, a magnet that can be activated for the clamping of the tool to a base, an adjustable arm with a cutting or grinding disc, where the arm is arranged to be moved by a motor driven spindle and on a longitudinal glide rail between predetermined points, where the glide rail is placed between said end supports,
a control cabinet for control and supply of air to the tool, and a control cabinet for control and supply of water to the tool, whereby the longitudinal movement of the arm and the adjustment to the cutting or grinding area is arranged to be controlled by air, while the cutting or grinding disc is arranged to be driven by air and cooled by water.
Alternative embodiments are defined in the dependent claims 2 - 6.
The spindle can be driven by an air motor at one or both ends and a clutch which is activated by a number of air cylinders can be arranged between the air motor and the spindle.
The longitudinal movement of the arm on the glide rail can be controlled by contact switches that can be displaced and fixed. Alternatively, the arm can also be fastened to a crosswise slide.
Furthermore, the arm can comprise devices for supply of water to the cutting or grinding disc, arranged to ensure that the temperature of the working area is kept below a predetermined limiting value. The temperature can be adapted to be held below 80 0 C, preferably below 65 0 C.
The invention shall now be explained in more detail with reference to the enclosed figures, in which:
Figure 1 shows a perspective drawing of an example embodiment of a tool according to the invention.
Figure 2 shows a partially exploded drawing of the tool shown in figure 1.
Figures 3a and 3b show in more detail the motor and clutch system of the embodiment shown in the figures 1 and 2.
Figure 4 shows a cutting and grinding arm of the tool shown in the figures 1 and 2.
Figure 5 shows a connecting diagram for the control system of the tool according to the invention.
The tool 20 itself, according to the invention, shall now be explained with the help of figures 1 -4. As can be seen, the tool 20 according to the invention comprises a frame which can be made up of an end support 22a, 22b arranged at each end of a between-lying glide rail and fastening rail 24. The end supports 22a, 22b are preferably equipped with corner legs 26 with wheels to help the movement of the tool 20. For the clamping of the tool to the base, a magnet 28, the height of which can be adjusted, is mounted to each end support 22a, 22b. The magnet can be switched on and off during use and is selected to be strong enough to keep the tool rigidly- clamped to the base, for example, with a pulling power of 250 kg to 500 kg.
A control cabinet 36 for control and supply of air to the tool and a control cabinet 38 for control and supply of water to the tool are arranged to the glide and fastening rail 24. Said cabinets can, of course, be integrated into each other.
An arm 30 adjustable and movable in the longitudinal direction with a cutting or grinding disc 32 is mounted to the glide rail 24. This arm 30 is, for example, via a plate and associated connecting appliance, linked to a spindle 34 arranged in the glide rail 24. The spindle 34 is driven by at least one air motor Ml, M2, so that the whole arm can be moved forwards and backwards along the glide rail 24. A clutch 40 that can be activated is coupled to each air motor and is controlled by associated air cylinders C2, C3, C4, C5 (figure 5) .
The arm 30 is fastened to a fastening plate 44 which in turn is fastened to a connecting plate 46. The connecting plate 46 is connected to the spindle 34 and rests preferably on the glide rail 24. The arm 30 is adjusted with the help of an air cylinder Cl towards and away from the working area of the disc 32. The arm 30 can be equipped with a stabiliser 50. Furthermore, the disc 32 is driven by an air motor 48, while water is supplied during operation (not shown) with the help of appliances for supply of water to the cutting or grinding disc 32, arranged to ensure that the temperature of the working area is held below a predetermined limiting value, for example, to be held below 80 0 C, preferably below 65 0 C. This water cooling results in maximum temperatures during operation being reduced considerably. In environments where there is a danger of explosions, this is of vital importance to obtain permission of use.
Tests have shown that the maximum temperature which was reached with use of the tool, during maximum load, was around 76 0 C. In use of the grinding disc during normal use, the maximum temperatures were measured to about 62 0 C. Tests carried out without the use of water cooling show that the highest temperatures arise on those places where friction is highest, and temperatures up to 300 0 C were measured. With the use of water cooling according to the present invention such use will not represent any real danger of ignition in explosive environments.
In an alternative embodiment of the invention (not shown) the arm 30 can be fastened to a cross-wise slide so that cutting or grinding operations can also be carried out across the longitudinal direction of the tool. The tool is otherwise built up corresponding to the above description.
The control system (Figure 5) shall now be explained:
The valve Q3 receives a supply of air from the main air supply, and the valve controls a water box, said water box supplies air and water to the adjustable arm with the cutting or grinding disc. When the control air 12 receives water from the valve Q6, the supply to the water box is OFF and the disc stops rotating. When the control air 14 receives air from the valve Q5, the supply to the water box is ON and if the water supply is OK, the disc starts to rotate. The valve Q4 controls the air cylinder Cl which in turn controls the cutting arm 30 and receives air from the main air supply. It is connected to the cylinder in both positions. When the control air 12 receives air from a switch Kl, the air cylinder returns to zero position and when the control air 14 receives air from the switch K2, the air cylinder is moved forwards.
The valve Q5 supplies the air motors Ml and M2, which control the spindle and the air cylinders C2, C3, C4, C5, which control the connecting and disconnecting of the motors. The valve receives air from the valve Q6. When control air 12 receives air from the switch K2 the motor M2 is supplied air and when control air 14 receives air from the switch Kl the motor Ml is supplied air. The valve Q6 is a start and stop valve and supplies the valve Q5 and control air to the valve Q3. When control air 12 receives air from S2 (the starter switch) the valve Q5 is supplied air. When control air 14 receives air from K4 (stop signal) , both valves Q3 and Q4 are supplied with control air on 12.
The contact switch Kl (roller switch) receives a supply of air from the main air supply and switches off the air motor Ml through the valve Q5 and switches on the air motor M2. It also switches off Q4 and the cylinder Cl returns to zero position. Furthermore, it provides control air to the valve K3 which is a counter. The contact switch K2 receives air from the main air supply and switches the air motor M2 off through the valve Q5 and the air motor Ml
on. It also switches on the valve Q4 and the cylinder Cl is moved forwards to a grinding or cutting position.
The counter K3 counts the number of cycles during working operations and receives air from the main air supply.
Furthermore, it provides air to the control air 14 on the valve Q6 through K4 , and receives control air Y from the starter switch S2 and receives control air Z from Kl. K4 receives a signal from the stop valve Sl or the counter K3 and gives the signal 14 to the valve Q6.
The stop switch Sl is activated manually and is used to switch off the system, and receives control air from the main air supply. It provides air to the control air 14 on the valve Q6 through K4. The starter switch S2 is activated manually and is used to switch on the system, and receives control air from the main air supply. It provides air to the control air 12 on the valve Q6 and it sets the counter K3 to the set number of cycles.