WO2018154173A1

WO2018154173A1 - Electrode slipping device

Info

Publication number: WO2018154173A1
Application number: PCT/FI2017/050126
Authority: WO
Inventors: Jarmo JOKINEN; Seppo JUVONEN
Original assignee: Outotec Finland Oy
Current assignee: Outotec Finland Oy
Priority date: 2017-02-27
Filing date: 2017-02-27
Publication date: 2018-08-30
Anticipated expiration: 2019-08-27
Also published as: ZA201905163B; EP3586569A1; PL3586569T3; CA3052687A1; EA201991785A1; CN110326360A; LT3586569T; EP3586569B1; CA3052687C; EP3586569A4; EA037728B1; CN110326360B

Abstract

An electrode slipping device (1) comprises an upper holder ring (2) and a lower holder ring (3) having one or more clamping assemblies including a clamping shoe (4) and a clamping device(5). The clamping shoe (4) is operable between a clamping position and a release position. The clamping device (5) comprises a frame element (6) fixedly attachable to a holder ring (2, 3) to be stationary in relation to the holder ring, a cylinder portion (7), a plunger (8) and a pressing spring (11) arranged inside the cylindrical housing (9) of the plunger (8) for urging the plunger (8) to- wards the clamping shoe (4) and for pressing the clamping shoe (4) against the electrode (E). A tension bar (12) is releasably attached to the end plate (10) of the plunger (8). A piston element 15) is arranged movable inside the cylinder portion (7) to form a hydraulic power means (16). The clamping device (5) com- prises one and single tension bar (12) arranged centrally in relation to the frame element (6), the plunger (8), the pressing spring (11) and the piston element (15).

Description

ELECTRODE SLIPPING DEVICE FIELD OF THE INVENTION

The present invention relates to an electrode slipping device.

BACKGROUND OF THE INVENTION

In prior art, e.g. documents WO 2015/001180 Al and WO 2015/001179 Al disclose an electrode slipping device according to the preamble of claim 1. Also Figure 1 shows this kind of an electrode slipping device hav^¬ ing, on the left side encircled with a dot-and-dash line denoted with A, two prior art clamping devices 5' mounted on the upper holder ring 2 and on the lower holder ring 3. Figure 2 shows such a prior art clamping device 5' . The clamping device 5' comprises a frame element 6' which is attachable to a holder ring 2 and/or 3 to be stationary in relation to the holder ring. A cylinder portion 7' is stationary in relation to the frame element 6' . A plunger 8 is arranged to be engaged with a clamping shoe (not shown) . The plunger 8 comprises a cylindrical housing 9' and an end plate 10' (not shown) . A pressing spring (not shown) is arranged inside the cylindrical housing 9' to act be- tween the frame element 6' and the plunger 8' for urg^¬ ing the plunger 8' towards the clamping shoe and for pressing the clamping shoe against the electrode E. Four tension bars 12' are arranged outside the cylin^¬ drical housing 9' inside which the pressing spring is located. Each tension bar 12' has a first end which is releasably attached to the end plate 10' of the plunger 8' . A piston element (not shown) is arranged movable inside the cylinder portion 1' to form a hydraulic power means 16' wherein the piston element can be moved by hydraulic pressure of hydraulic fluid which is arranged to be guided to a space between the piston element and the cylinder portion. Movement of the piston element by hydraulic pressure of the hy^¬ draulic fluid causes the tension bars 12' to pull the plunger 8 against the spring force of the pressing spring to move the clamping shoe from a clamping posi- tion to a release position.

As mentioned, the four tension bars are located out^¬ side the cylindrical housing which accommodates the pressing spring. This kind of arrangement of tension bars makes the clamping device bulky and heavy. The end plates, to which the tension bars are attached, must be both wide and thick to be sturdy enough to withstand the bending force caused by the pressing spring acting on the central region of the end plate and at a distance from the support points to tension bars, in order to avoid bending of the end plates. The clamping device also has many parts making it complicated and expensive to manufacture and difficult to service .

OBJECTIVE OF THE INVENTION

The objective of the invention is to alleviate the disadvantages mentioned above. In particular, it is an objective of the present in^¬ vention to provide an electrode slipping device having a clamping device which has a simple, compact and light-weight structure with few parts, easy to mainte^¬ nance and cheap to manufacture.

SUMMARY OF THE INVENTION

According to an aspect of the invention, the present invention provides an electrode slipping device com^¬ prising an upper holder ring and a lower holder ring, the upper holder ring and the lower holder ring containing one or more clamping assemblies including a clamping shoe and a clamping device arranged in co- operation with each other, so that the clamping shoe is operable between a clamping position, where an electrode is clamped, and a release position, where the electrode is undamped. The clamping device com- prises a frame element fixedly attachable to a holder ring to be stationary in relation to the holder ring. The clamping device comprises a cylinder portion, the cylinder portion being arranged stationary in relation to the frame element. The clamping device comprises a plunger, the plunger comprising a cylindrical housing and an end plate arranged to be engaged with the clamping shoe. The clamping device comprises a press^¬ ing spring arranged inside the cylindrical housing to act between the frame element and the plunger, for urging the plunger towards the clamping shoe and for pressing the clamping shoe against the electrode. The clamping device comprises a tension bar having a first end releasably attached to the end plate of the plung^¬ er, and a second end. The clamping device comprises a piston element arranged movable inside the cylinder portion to form a hydraulic power means wherein the piston element can be moved by hydraulic pressure of hydraulic fluid which is arranged to be guided to a space between the piston element and the cylinder por- tion. Movement of the piston element by hydraulic pressure of the hydraulic fluid causes the tension bar to pull the plunger against the spring force of the pressing spring to move the clamping shoe from the clamping position to the release position.

According to the invention the clamping device comprises one and single tension bar arranged centrally in relation to the frame element, the plunger, the pressing spring and the piston element.

The advantage of the invention is that due to one and single central tension bar the clamping device can be a simple, compact and light-weight structure with few parts, being easy to maintenance and cheap to manufac^¬ ture. The single centrally arranged tension bar ena^¬ bles that a thick end plate is not needed since the tension bar does not exert bending forces to the end plate, as happens in the prior art device. For exam^¬ ple, a prior art clamping device having a pressing force 60 tn may have a weight 450 kg. The weight of the clamping device according to the invention with the same pressing force may be less than 300 kg. Re^¬ duction of weight is considerable.

In an embodiment of the electrode slipping device, the frame element, the plunger and the pressing spring each have a central hole to receive the tension bar therein .

In an embodiment of the electrode slipping device, the end plate has a central hole having an inner thread, and that the first end of the tension bar has a first outer thread threaded to the inner thread of the end plate .

In an embodiment of the electrode slipping device, the second end of the tension bar has a second outer thread on which a lock nut is threaded.

In an embodiment of the electrode slipping device, the clamping device comprises two or more cylinder por- tions and piston elements disposed radially around the tension bar to form two or more hydraulic power means around the tension bar.

In an embodiment of the electrode slipping device, the clamping device comprises three or four cylinder portions and piston elements disposed radially around the tension bar to form three or four hydraulic power means around the tension bar.

In an embodiment of the electrode slipping device, the clamping device comprises a second end plate to which the piston elements are attached, the second end plate comprising inlets and outlets for guiding the hydrau^¬ lic fluid to and from the two or more hydraulic power means .

In an embodiment of the electrode slipping device, the cylinder portion and the piston element are both annular thereby forming an annular hydraulic power means which is concentric in relation to the tension bar.

In an embodiment of the electrode slipping device, the frame element comprises an inlet and an outlet for guiding the hydraulic fluid to and from the annular hydraulic power means

In an embodiment of the electrode slipping device, the pressing spring consists of a plurality of conical disc spring washers.

In an embodiment of the electrode slipping device, the lower holder ring comprises a single clamping device configured to releasably press one clamping shoe against the surface of the electrode. Further the low^¬ er holder ring comprises a contact shoe made of elec^¬ trically conductive material for supplying current to the electrode, the contact shoe being arranged at an opposite side of the lower holder ring in relation to the position of the clamping shoe.

In an embodiment of the electrode slipping device, the upper holder ring is attached to a stationary structure, and that the lower holder ring is suspended from the stationary structure by vertical hydraulic cylin^¬ ders .

It is to be understood that the aspects and embodi- ments of the invention described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to pro^¬ vide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the de- scription help to explain the principles of the inven^¬ tion. In the drawings:

Figure 1 shows an axonometric view of an electrode slipping device provided with clamping devices accord- ing to prior art A and according to a first embodiment of the invention B,

Figure 2 shows an axonometric view of a prior art clamping device,

Figure 3 shows an axonometric view of a clamping de^¬ vice of a first embodiment of the electrode slipping device of the invention, Figure 4 shows an axonometric view of an electrode slipping device according to a second embodiment of the invention,

Figure 5 shows a cross-section V-V from Figure 4,

Figure 6 shows a side view of a clamping device of Figure 5, Figure 7 shows an end view VII-VII of the clamping de^¬ vice of Figure 6, Figure 8 shows a cross-section VIII-VIII from Figure 6,

Figure 9 shows a longitudinal cross-section of a fur^¬ ther embodiment of a clamping device in a clamping po- sition I wherein the hydraulic power means is unpres- surized, and

Figure 10 shows the clamping device of Figure 9 in in a release position wherein the hydraulic power means is pressurized.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows an electrode slipping device 1 which is for holding and slipping of a self-baking Soderberg electrode E. The slipping device 1 comprises an upper holder ring 2 and a lower holder ring 3. The upper holder ring 2 and the lower holder ring 3 both comprise several clamping assemblies including a clamping shoe (not shown in Figure 1) and a clamping device 5 arranged in co-operation with each other. The clamping shoe is operable between a clamping position where an electrode E is clamped and held in its position and a release position where the electrode E is undamped and can be moved. The operation principle of the clamping device 5 is explained in more detail with reference to Figure 9 and 10.

The operation principle of the slipping device 1 is known from the prior art. The slipping device allows controlled displacement of the electrode. The upper and lower holder rings 2, 3, are sequentially operated and moved to extend the electrode as the tip of the electrode is consumed in use in the furnace. The two holder rings 2, 3 are connected with vertical hydrau^¬ lic cylinders 100 that enable relative movement be^¬ tween the upper and lower holder rings. This action enables slipping through of the electrode whilst al^¬ ways maintaining a positive grip on the outer surface of the electrode.

In Figure 1 the clamping devices 5 according to the invention are installed in the upper and lower holder rings 2, 3 and are shown on the right side and encir^¬ cled by a dot-and-dash line denoted by B. The clamping device 5 is also shown in Figure 3. When compared to the prior art clamping device 5' shown in Figure 2, Figure 3 shows that the new clamping device 5 is a more simple, compact and light-weight structure with fewer parts.

The structure of the clamping device 5 is disclosed in more detail with reference to Figures 5 to 10 in the following .

As shown in Figures 5, 9 and 10 the clamping device 5 comprises a frame element 6 which is fixedly attached to a lower holder ring 3 to be stationary in relation to the holder ring. A cylinder portion 7 is arranged stationary in relation to the frame element 6. The cylinder portion 7 may be a separate part in relation to the frame element 6 whereby the cylinder portion 7 is attached to the frame element 6. The clamping ele^¬ ment 5 comprises a plunger 8. The plunger 8 comprises a cylindrical housing 9 and an end plate 10. The end plate 10 can be engaged with the clamping shoe 4 to press it. A pressing spring 11 is arranged inside the cylindrical housing 9. The pressing spring 11 acts be^¬ tween the frame element 6 and the end plate 10 of the plunger 8 urging the plunger 8 towards the clamping shoe 4 and for pressing the clamping shoe 4 against the electrode E.

One and single centrally disposed tension bar 12 is releasably attached to the end plate 10 of the plunger 8. The end plate 10 has a central hole 19 having an inner thread 20. The first end 13 of the tension bar 12 has a first outer thread 21 which is threaded to the inner thread 20 of the end plate 10 to provide a releasable attachment.

A piston element 15 is arranged movable inside the cylinder portion 7 of the frame element 6 to form a hydraulic power means 16. The piston element 15 can be moved by hydraulic pressure of hydraulic fluid which is guided into a space S between the piston element 15 and the cylinder portion 7. Movement of the piston element 15 by hydraulic pressure of the hydraulic fluid causes the tension bar 12 to pull the plunger 8 against the spring force of the pressing spring 11 to move the clamping shoe 4 from the clamping position I (Figure 9) to the release position II (Figure 10) .

As shown in Figure 9, in the clamping position I the hydraulic power means 16 is unpressurized and the pressing spring 11 urges the plunger 8 to press the clamping shoe (not shown) against the electrode (not shown) . In this position an end E of the cylinder portion 9 of the plunger 8 is at a distance from a stopper F formed by a surface of the frame element 6.

As shown in Figure 10, in the release position II the hydraulic power means 16 is pressurized and the press^¬ ing spring 11 is pulled by the tension bar 12 to a shortened state wherein the end E of the cylinder por^¬ tion 9 of the plunger 8 abuts against stopper F. In this position the clamping shoe (not shown) is pulled away from contact to the electrode (not shown) and the electrode is free to be moved.

The one and single tension bar 12 is arranged central- ly in relation to the frame element 6, the plunger 8, the pressing spring 11 and the piston element 15. The frame element 6, the plunger 8 and the pressing spring 11 each have a central hole 17, 18, 19 to receive the tension bar 12 therein. The second end 14 of the ten- sion bar 12 has a second outer thread 22 on which a lock nut 23 is threaded.

Figures 5 to 8 show an embodiment of the clamping de^¬ vice 5 which comprises four cylinder portions 7 and four piston elements 15 disposed radially around the tension bar 12 to form four hydraulic power means 16 around the tension bar 12. The clamping device 5 comprises a second end plate 24 to which the piston ele^¬ ments 15 are attached. The second end plate 24 com- prising inlets 25 and outlets 26 for guiding the hy^¬ draulic fluid to and from the two or more hydraulic power means 16. Preferably the inlet 25 is at a lower level than the outlet 26 in order to prevent formation of air bubbles in the hydraulic fluid. In Figure 7 can be seen that the four hydraulic cylinder means are connected in series so that the hydraulic fluid flows through all four hydraulic power means 16.

Figures 9 and 10 show another embodiment wherein the cylinder portion 7 and the piston element 15 are both annular thereby forming one annular hydraulic power means 16 which is concentric in relation to the ten^¬ sion bar 12. An annular hydraulic power means 16 is compact and can provide a great force. In this embod- iment the cylinder portion 7 comprises an inlet 25 and an outlet 26 for guiding the hydraulic fluid to and from the annular hydraulic power means 16. Preferably the outlet 26 is above the level of the inlet 25 in order to prevent formation ofairb bubbles in the hy^¬ draulic fluid.

In the embodiments shown in Figures 5, 9 and 10 the pressing spring 11 consists of a plurality of conical disc spring washers 27, so-called Belleville washers, arranged as a stack.

The hydraulic power means 16 of the clamping devices 5 of both embodiments of Figure 5 and Figure 9 can be easily detached for service simply by removing the lock nut 23 and by unthreading the tension bar 12 from the end plate 10 whereby the frame element 6, plunger 8 and the pressing spring can remain in its place to press the clamping shoe 4 while the cylinder portion 7 and the piston element 15 are detached.

Reference is now made to Figures 4 and 5. Figure 4 shows an electrode slipping device 1 designed for graphite electrode. The lower holder ring 3 comprises a single clamping device 5 arranged to releasably press one clamping shoe 4 against the surface of the electrode E (shown in Figure 5) . The lower holder ring also comprises a single contact shoe 28 made of elec^¬ trically conductive material for supplying current to the electrode. The contact shoe 28 is arranged at an opposite side of the lower holder ring 3 in relation to the position of the clamping shoe 4. AS can be seen in Figure 4, the upper holder ring 2 is attached to a stationary structure 29. The lower holder ring 3 is suspended from the stationary structure 29 by vertical hydraulic cylinders 30.

Although the invention has been the described in conjunction with a certain type of the slipping device, it should be understood that the invention is not lim^¬ ited to any certain type of the slipping device. While the present inventions have been described in connec^¬ tion with a number of exemplary embodiments, and implementations, the present inventions are not so lim^¬ ited, but rather cover various modifications, and equivalent arrangements, which fall within the purview of prospective claims.

Claims

1. An electrode slipping device (1) comprising an upper holder ring (2) and a lower holder ring (3), the upper holder ring and the lower holder ring containing one or more clamping assemblies including a clamping shoe (4) and a clamping device (5) arranged in co^¬ operation with each other so that the clamping shoe (4) is operable between a clamping position (I), where an electrode (E) is clamped, and a release position (II), where the electrode (E) is undamped, and where^¬ in the clamping device (5) comprises

- a frame element (6) fixedly attachable to a holder ring (2, 3) to be stationary in relation to the holder ring,

- a cylinder portion (7), the cylinder portion (7) being arranged stationary in relation to the frame element (6),

- a plunger (8), the plunger (8) comprising a cylindrical housing (9) and an end plate (10) arranged to be engaged with the clamping shoe (4),

- a pressing spring (11) arranged inside the cylindrical housing (9) to act between the frame ele^¬ ment (6) and the plunger (8), for urging the plunger (8) towards the clamping shoe (4) and for pressing the clamping shoe (4) against the electrode (E) ,

- a tension bar (12) having a first end (13) releasably attached to the end plate (10) of the plunger (8), and a second end (14),

- a piston element (15) arranged movable in^¬ side the cylinder portion (7) to form a hydraulic power means (16) wherein the piston element can be moved by hydraulic pressure of hydraulic fluid which is ar^¬ ranged to be guided to a space between the piston ele- ment (15) and the cylinder portion (7),

whereby movement of the piston element by hy^¬ draulic pressure of the hydraulic fluid causes the tension bar to pull the plunger (8) against the spring force of the pressing spring (11) to move the clamping shoe (4) from the clamping position (I) to the release position (II) , c h a r a c t e r i z e d in that the clamping device (5) comprises one and single tension bar (12) arranged centrally in relation to the frame element (6), the plunger (8), the pressing spring (11) and the piston element (15) .

2. An electrode slipping device according to claim 1, c h a r a c t e r i z e d in that the frame element (6) , the plunger (8) and the pressing spring (11) each have a central hole (17, 18, 19) to receive the tension bar (12) therein.

3. An electrode slipping device according to claim 1 or 2, c h a r a c t e r i z e d in that the end plate (10) has a central hole (19) having an inner thread (20), and that the first end (13) of the tension bar (12) has a first outer thread (21) threaded to the in^¬ ner thread (20) of the end plate (10) .

4. An electrode slipping device according to any one of the claims 1 to 3, c h a r a c t e r i z e d in that the second end (14) of the tension bar (12) has a sec^¬ ond outer thread (22) on which a lock nut (23) is threaded .

5. An electrode slipping device according to any one of the claims 1 to 4, c h a r a c t e r i z e d in that the clamping device (5) comprises two or more cylinder portions (7) and piston elements (15) disposed radial^¬ ly around the tension bar (12) to form two or more hydraulic power means (16) around the tension bar.

6. An electrode slipping device according to claim 5, c h a r a c t e r i z e d in that the clamping device (5) comprises three or four cylinder portions (7) and pis^¬ ton elements (15) disposed radially around the tension bar (12) to form three or four hydraulic power means (16) around the tension bar.

7. An electrode slipping device according to claim 5 or 6, c h a r a c t e r i z e d in that the clamping de^¬ vice comprises a second end plate (24) to which the piston elements (15) are attached, the second end plate (24) comprising inlets (25) and outlets (26) for guiding the hydraulic fluid to and from the two or more hydraulic power means (16) .

8. An electrode slipping device according to any one of the claims 1 to 4, c h a r a c t e r i z e d in that the cylinder portion (7) and the piston element (15) are both annular thereby forming an annular hydraulic power means (16) which is concentric in relation to the tension bar (12) .

9. An electrode slipping device according to claim 8, c h a r a c t e r i z e d in that the frame element (6) comprises an inlet (25) and an outlet (26) for guiding the hydraulic fluid to and from the annular hydraulic power means (16)

10. An electrode slipping device according to any one of the claims 1 to 9, c h a r a c t e r i z e d in that the pressing spring (11) consists of a plurality of conical disc spring washers (27) .

11. An electrode slipping device according to any one of the claims 1 to 10, c h a r a c t e r i z e d in that the lower holder ring (3) comprises

- a single clamping device (5) arranged to releasably press one clamping shoe (4) against the surface of the electrode (E) , and - a contact shoe (28) made of electrically conductive material for supplying current to the electrode, the contact shoe (28) being arranged at an opposite side of the lower holder ring (3) in relation to the posi- tion of the clamping shoe (4) .

12. An electrode slipping device according to claim 11, c h a r a c t e r i z e d in that the upper holder ring (2) is attached to a stationary structure (29), and that the lower holder ring (3) is suspended from the stationary structure (29) by vertical hydraulic cylinders (30) .