EP0090824B1

EP0090824B1 - Equipment for the treatment of cylindrical hollow structures by means of blast cleaning

Info

Publication number: EP0090824B1
Application number: EP82902984A
Authority: EP
Inventors: Markku Juhani Fingerroos
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-10-02
Filing date: 1982-10-01
Publication date: 1986-08-20
Also published as: FI813064L; WO1983001220A1; DE3272741D1; FI64904B; EP0090824A1; FI64904C; JPS58501622A

Abstract

It is known in prior art to treat the inside face of a pipe by means of a so-called spear device, which is provided with one or several nozzles, whereby, when the nozzles progress axially in relation to the pipe to be treated, this pipe is, at the same time, by means of a rotating device, made to revolve around its axis. This prior-art solution, however, involves the drawback that the blasting sand tends to remain in the pipe, from where it must be removed by means of separate compressed-air blowing. According to the invention, a combined transfer and rotating device is used which comprises two wheel sets (2 to 8) placed side by side, the structure (1) to be treated resting and being rotatable around its own axis on the said wheel sets. When the angular position of the wheels (2) in the wheel sets is changed, the rotating device is converted into a transfer device, by means of which the structure (1) to be treated can be shifted into and out of the blast chamber. The equipment includes a spear device (23), which comprises two blasting spears, by means of which both inside and outside cleaning of the structure (1) to be treated can be performed simultaneously.

Description

The present invention is concerned with an equipment in accordance with the preamble of claim 1. Equipment of this type is used when especially metallic pipes are treated by means of simultaneous inside and outside sand blasting of blast cleaning.
Such equipment usually comprises a blast chamber as well as transfer means for shifting the structure to be treated into and out of the blast chamber. The blasting material of steel, quartz, or of any other suitable cleaning material is blasted by means of compressed air through nozzles against the face to be treated.
An apparatus according to the precharacterizing features of claim 1 is known from DE-A-2 852 106 being the nearest relevant art. This known apparatus comprises a blast chamber and two transfer wheel sets placed side by side, for shifting the structure to be treated axially into and out of the blast chamber. Each wheel set consists of a plurality of wheels, which are preferably of equal size and which can be rotated in a position oblique to the direction of shifting of the structure to be treated, at least some of which are motor-driven, and on whose support the structure can be, at one time or another, both shifted axially and rotated around its axis.
This prior-art solution, however, involves the drawback that the blasting material tends to remain in the pipe, from which it must be removed by means of separate blowing by compressed air. Moreover, the fact that the cleaning operations directed at the inside and the outside faces of the structures to be treated take place at different times makes the treatment prolonged and inconvenient. At the same time, it has been difficult to treat pipes of different diameters by means of the same equipment, because there has been no sufficient adjustability.
The object=-of the present invention is to eliminate the above drawbacks and to provide equipment of an entirely novel type for the rotation and axial transport of cylindrical hollow structures.
The invention is based, e.g., on the following ideas:

A combined transfer and rotating device is used, which comprises two wheel sets placed side by side, on which wheel sets the structure to be treated rests and can be rotated around its own axis. When the angle position of the wheels in the wheel sets is changed, the rotating device is converted into a transfer device, by means of which the structure to be treated can be shifted into and out of the blast chamber.

More specifically, the equipment in accordance with the invention is mainly characterized in what is stated in the characterizing part of claim 1.
By means of the invention, remarkable advantages are achieved. Thus, as the inside and outside cleaning is performed at the same time, considerable economies of time are achieved. Since a correct choice of pressure and speed of rotation causes the cleaning material to be removed from the interior of the structure to be treated automatically, this also allows to avoid unnecessary consumption of time for additional cleaning. Owing to a pivotable wheel set, the transfer and the rotation are efficient and rapid since they are performed by means of one apparatus.
The invention will be examined in more detail below by means of the exemplifying embodiment in accordance with the attached drawings.

Figure 1 is a schematical side view of the equipment in accordance with the invention before the beginning of the blasting process.
Figure 2 shows the equipment of Fig. 1 during the blasting process.
Figure 3 shows the equipment in accordance with the invention as viewed from the end placed next to the feeding table.
Figure 4 shows the equipment in accordance with the invention as a cross section at the blast chamber.
Figure 5 is a side view showing the relative connections between the sand-feed containers and the blasting spears.
Figure 6 shows the combination of Fig. 5 as viewed from the end next to the spear device of the equipment.
Figure 7 is a side view of the blasting spears at the ends next to the nozzles.

In the starting situation in accordance with Fig. 1, the pipe 1 to be treated has been shifted from the feeding table 9 shown in Fig. 3 by means of a lever arm 10 operated by a hydraulic cylinder 12 onto the wheel sets 2. As comes out more clearly from Figures 3 and 4, these wheel sets comprise several wheel rims 2 of equal size, placed coaxially at a distance from one another, solid tyres 3, e.g. of rubber, being fitted on the circumference of the said rims. Some of these wheels 2 are freely revolving, whereas some of them are motor-driven, preferably inverter-operated.
As comes out mainly from Fig. 4, the wheels 2 are, by means of journalling 6, attached to the V-shaped bottom part of the blast chamber so that they can be diverted from their rotating position, in the radial plane, to the transfer position so as to achieve axial shifting of the structure 1. This diverting takes place by means of a longitudinal rod 8, which is connected to a lever 7 related to the journalling of each wheel 2. In this way, all the wheels of both wheel sets 2 are automatically always shifted into the same angular position.
After the pipe 1 has been, by means of the wheel sets 2, shifted into the blast chamber in accordance with Fig. 2, the position of the wheels 2 is restored to the radial plane so that the pipe 1 revolves in the blast chamber 13 around its axis as supported on its wheel sets 2. At the same time, the spear device, which comprises an upper spear 19 and a lower spear 23, placed directly underneath the upper spear, as well as material feed containers 28 and 30 connected to the said spears, is shifted as one unit into connection with the pipe 1 to be treated. Then, the upper spear 19 moves slowly into the pipe 1 while the pipe revolves, and at the same time the lower spear 23 moves to underneath the pipe 1, while blasting material is blown by means of compressed air through the nozzles 20 and 24, respectively, onto the inner and outer face of the pipe. The compressed-air device, which is not shown, is connected to the spears 19 and 23 at points places behind the material feed containers 28 and 30. From these containers 28 and 30, the blasting material has access into the spears 19 and 23 through pipes 29 and 31 and through valves, not shown, placed in the said pipes. The combination of spears and containers moves on the wheel set 32 along rails 33. Moreover, the lower spear 23 is, by means of a support wheel 25, 26 of its own, arranged so as to be supported at one end against the above V-section bottom groove. On the other hand, the upper spear 19 is, by means of resilient guide wheel sets 21, 22 fitted centrally to move inside the pipe 1.
Both of the blasting spears 19 and 23 are dimensioned at least approximately equally and connected to a preferably common pressure source so that the pressure to be used is 5 - 105 to 15 - 10⁵ N/m² (5 to 15 bars), most appropriately about 10.105 N/m² (10 bars). Moreover, as the wheel sets 2 have been arranged so as to make the pipe 1 to be treated rotate at a speed of 20 to 70 r.p.m., preferably about 30 to 40 r.p.m., by the combined effect of the pressure and of the speed of revolution applied, a phenomenon of hovering of the blasting material inside the pipe 1 is produced. This is why the blasting material is automatically removed out of the pipe 1 through one of its ends onto the bottom of the blast chamber 13. The material blasted out of the lower spear 23 likewise falls onto the bottom of the blast chamber 13. All of this material that was used can flow through a longitudinal slot 16 in the bottom 15 of the blast chamber to a, likewise longitudinal, trough 17 placed underneath the bottom 15, a screw conveyor 18 placed in the said trough shifting the material used further for recovery.
As comes out from Figures 3 and 4 the equipment in accordance with the invention is very well suited for the treatment of tubular structures of different sizes both at the factory and at a construction site.
Since the effect of the diameter of the_pipe 1 to be treated is not large on the distance of the lower spear 23 from the bottom face of the pipe 1, the level of the lower spear 23 does not necessarily have to be adjusted in accordance with the size of the pipe 1 to be treated. On the contrary, adjustability of the upper spear 19 at the root end may be important in order to give consideration to different pipe sizes, even though the flexible guide wheel sets 21, 22 also automatically take such variations at the nozzle end of the spear 19 into account.
It should be mentioned that the speed of movement of the spear device is preferably continuously adjustable, owing to which the degree of cleaning can be selected freely.

Claims

1. Equipment for the treatment of cylindrical hollow structures (1) and especially of metallic pipes inwardly and outwardly by means of blast cleaning, which equipment comprises

a blast chamber (13),

two transfer wheel sets (2) placed side by side, for shifting the structure (1) to be treated axially into and out of the blast chamber (13), each wheel set (2) consisting of a plurality of wheels (2), which are preferably of equal size, which can be rotated in a position oblique to the direction of shifting on the structure (1) to be treated, at least some of which are motor-driven, and on whose support the structure (1) can be, at one time or another, both shifted axially and rotated around its axis characterized in that the wheels (2) can be pivoted from their said oblique shifting position to such a rotating position in which the axes (5) of the wheels of both wheel sets (2) are on their own common geometric axis, which is at least substantially parallel to the direction of shifting of the structure (1) to be treated, and that there is further provided

a spear device comprising two blasting spears (19, 23) for blasting and blasting medium through spears (20, 24) simultaneously onto the inner and outer faces of the structure (1), -

a compressed-air source for supplying compressed air into the spear device (19, 23), and blasting medium feed means (28, 30) for feeding blasting medium into the spear device (19, 23).

2. Equipment as claimed in claim 1, characterized in that the wheels (2) in both wheels sets (2) have been journalled so that, by means of a common axial rod (8) or equivalent and of a lever (7) belonging to each wheel (2), they can be simultaneously pivoted to a position diverging from the radial plane.

3. Equipment as claimed in claim 1, characterized in that the wheels (2) are provided with solid tyres i3) of a material, such as rubber.