MELTING HEAD FOR ICE-MELTING APPARATUS

Abstract

The invention relates to a melting head (1) for an ice melting apparatus (1, 8) comprising a rear, in relation to the propagation direction, attachment region (4) for attaching to a drilling apparatus (8) or a drilling rod assembly, and a forward, in relation to the propagation direction, heatable front region (1c), wherein the front region (1c) has a radially outer face region (1a) in which the front region (1c) has an outer cross section that tapers in the propagation direction (3) up to the forward axial melting head end (1d), in particular with a tapering outer diameter, and the radially outer face region (1a) surrounds an inner cavity (5), the free inner cross section of which reduces from the axial melting head end (1d) counter to the propagation direction (3). The invention also relates to an ice melting apparatus (1, 8) formed with the melting head (1).

Claims

1. A melting head of an ice-melting apparatus displaceable in a travel direction, the melting head comprising: a rear attachment end for attaching to a drilling string or a drill rod assembly; and a heatable front end formed with a forwardly open cavity and having a front edge and a radially outer surface that decreases in size in the travel direction up to the front axial melting-head edge, the radially outer surface surrounds the cavity whose free inner cross-section decreases from the front edge counter to the travel direction.

2. The melting head according to claim 1, wherein the melting head edge forms an annular border at which the radially outer surface and an inner surface of the inner cavity merge into each other and the front edge points forward in the travel direction and is formed sharp-edged or crowned or flattened.

3. The melting head according to claim 1, wherein the outer surface and the inner cavity are formed to be n-fold rotation-symmetrical about a central axis extending in the travel direction.

4. The melting head according to claim 1, wherein an axial length of the tapered radially outer surface and an axial depth of the inner cavity are equal.

5. The melting head according to claim 3, wherein in a region between a point of intersection of the inner cavity with the center axis and the axial melting-head edge, the surface sizes of the radially outer surface and the inner surface of the inner cavity are equal.

6. The melting head according to claim 1, wherein projected surfaces of the outer surface and an inner surface of the inner cavity projected in the travel direction are of the same area.

7. The melting head according to claim 1, further comprising: a plurality of heating elements embedded the front end between the tapered radially outer surface and an inner surface of the inner cavity.

8. The melting head according to claim 1, further comprising: a plurality of heating elements each inserted into a respective rear hole formed in the head, the heating elements and holes each having a radial spacing from the center axis that corresponds at least substantially to the radial spacing of the front edge.

9. The melting head according to claim 1, wherein the outer surface and the surface of the inner cavity each correspond to a conic section or a section of a paraboloid.

10. The melting head according to wherein the tapered front end forms a rotation body, in particular a frustoconical section or paraboloid section that is rotationally symmetrical about the center axis and whose end region is folded inward at the plane in which the melting-head edge lies so as to form the cavity.

11. The melting head according to claim 1, wherein apart from a sign and an axial displacement of double the axial length of the front end, the cross-sectional shape along the central axis of the outer surface and the surface of the inner cavity follow the same mathematical function depending on the radial spacing from the central axis.

12. An ice-melting apparatus, comprising a melting head according to claim 1, the head being at its rear attachment end in the travel direction connected to a drilling string, that comprises an axially extending tubularly cylindrical casing in which energy storage for the heating of heating elements of the melting head or an unwindable cable supply is contained.

Description

[0030] Embodiments of the invention are described in more detail with reference to the figures.

[0031] FIGS. 1A to 1D show different geometries of the outer surface 1a and inner surface 1b of a melting head 1 according to the invention in cross-section, i.e. cut in a plane including the center axis 2 of the melting head 1.

[0032] The travel direction 3 is shown for all FIGS. 1[A to D] by the arrow [3] to the left of FIGS. 1[A to D].

[0033] It can be seen for all embodiments of FIGS. 1[A to D] that the front end 1c of the melting head 1 has the radially outer surface 1a. Seen in cross-section perpendicular to the center axis 2 this surface tapers in the travel direction. With the rotational symmetry present here, the outer diameter of the outer surface 1a thus decreases in a direction from the rear attachment end 4 to the axially front melting-head edge 1d. The beginning of the taper at a collar 1e preferably defines here the axial beginning of the front end [1c], and the melting-head edge 1d defines the end of the front end [1c].

[0034] The upper views of circular areas above FIGS. 1A to 1D show the projected surfaces of the radially outer surface and the inner surface 1b of the cavity 5. According to the projected surfaces p1a and p1b, the embodiments represent the possibilities to make the sizes of the surfaces 1a and 1b or the sizes of the projections p1a and p1b the same or to make different sizes, in particular with the particular advantages as mentioned in the general part of the description.

[0035] FIG. 1A illustrates an embodiment in which the inner surface 1b and the outer surface 1a in the cross-section shown here are each a parabola. The two parabolas differ only in the sign and an offset along the center axis 2 and are otherwise parameterized identically. Thus, the mathematical description of the cross-sectional shape of both surfaces follows the same function depending on the radial spacing to the center axis 2, apart from the offset and an inversion. Due to the rotational symmetry, the shape in space in FIG. 1A is a paraboloid section of both surfaces. The same can apply to FIG. 1B to FIG. 1D where the function describes a straight line that, in the case of rotational symmetry, leads in space to the shape of a frustoconical section of both surfaces.

[0036] FIGS. 2[A to C] show different embodiments of the melting head 1 according to FIG. 1A, thus with respective paraboloid shapes of the inner and outer surfaces 1b and 1a.

[0037] In FIG. 2A, the front axial melting-head edge 1d on the axial end surface form a sharp edge, and in FIG. 2B, the melting-head edge 1d forms a rounded or crowned shape and in FIG. 2C a flattened shape.

[0038] The figures also show holes 6 that hold respective heating elements 6. This is also shown more clearly in FIG. 3. Here, it can be seen that the holes 6 and the respective heating elements 6 are arrayed on a circle with the radius that corresponds to the radial spacing of the melting-head edge 1d from the center axis 2.

[0039] As a result of this, at least the heat-emitting tips of the heating elements 6 are located, preferably centered, in an annulus 7 of the front end of the melting head, so that the heat emission thereof can take place both outward and inward over a short distance.

[0040] On the right side in FIG. 3 the rear attachment end 4 is shown extended toward the rear by a drilling string 8 with a cylindrical casing that can for example hold energy sources 9 for the heating elements 6 or other electronics 9 or cables 10 that are illustrated only symbolically here. Thus, the melting head 1 together with this drilling string 8 forms an ice-melting apparatus.

[0041] FIG. 4 shows clearly that in the preferred embodiment both the outer surface 1a and the inner surface 1b of the cavity 5 are described by the same parabolic formula P and differ only by an inversion I and an offset O along the center axis 2.

[0042] With the parameterization shown here, the axially front ring-shaped melting-head edge is located at position r=R/2.sup.2. Here, the inner and outer surfaces 1a and 1b merge into each other. R is the maximum outer diameter of the melting head 1 and h is the depth of the cavity 5 or, respectively, the height of the tapered front end or annulus 7.