The invention relates to a protective element for a wearing-part attachment for a wearing part for a leading edge of a working member, the wearing part and the wearing-part attachment being provided with complementary quick-coupling elements. Further, the invention relates to a method of wear- protecting a wearing-part attachment for a wearing part for a leading edge of a working member, the wearing part and the wearing-part attachment being provided with complementary quick-coupling elements.

Earth-working implements, for example ploughs, harrows, excavator buckets and so on, are often provided with replaceable wearing parts in the form of wearing points, teeth and so on. To facilitate the replacement of such wearing parts, it is known to attach the wearing part to a wearing-part attachment by means of a quick-coupling . To have a desired effect of the quick-coupling system, it is obvious that the lifetime of the wearing-part attachment must be at least double the lifetime of the wearing part. In practice, it has turned out that extraordinary precautions must be taken at the wearing-part attachment to achieve the desired lifetime. The precautions may include applying a harder material, for example by hardfacing with a hard-metal coating or soldering with hard-metal elements, to the surface or surfaces of the wearing-part attachment that is/are subjected to the greatest wear, typically portions facing the material flow passing the wearing-part attachment.

Welding or soldering involves the necessity of supplying a relatively large amount of heat energy to the wearing-part attachment for the wearing-part attachment to achieve the desired temperature so that a sufficiently good adherence is provided between the hard metal and the wearing-part attachment. It is known in the art that a great difference in mass between the elements that are to be joined is disadvantageous. For example, if the wearing-part attachment has been hardened prior to the application of hard metal, the supply of heat may take the hardening out of an unduly large portion of the wearing-part attachment. A similar problem is associated with treating the wearing-part attachment with other materials, for example carbon to car- bidize a portion of the wearing-part attachment, or nitrogen to nitrate a portion of the wearing-part attachment.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

An invention has been provided, in which a wearing-part attachment for a wearing part for a leading edge of an earth-working implement has been shielded by a separate protection element. The mass ratio of a wearing portion, with which a portion of the protection element is provided, to a supporting element of the protection element is favourable seen from a heat-economy point of view, as there is no supply of heat energy to the wearing-part attachment when the wearing portion is being attached.

The protection element is arranged upstream of a leading portion of the wearing-part attachment, as an attachment portion of the protection element is arranged to engage with quick-coupling elements on the wearing-part attachment or the wearing part, typically in the form of guiding portions formed as projecting ridges on the attachment portion of the wearing part and arranged to lockingly engage with complementary grooves in the wearing-part attachment. When the wearing part has been fixed to the wearing-part attachment, the protection element will be held in position between the wearing part and the wearing-part attachment and rest supportedly against a leading end face of the wearing-part attachment.

At least an upper portion of a leading side surface of the protection element is provided with a wearing portion, for example in the form of a hard metal, typically provided by a plate element, for example a carbide steel, having been attached to the leading side surface. It is conceivable for the wearing portion to be provided in a variety of ways. In its simplest form, a plate element from a carbide steel can be soldered or glued to the protection element, a ceramic plate element can be glued, a hard-metal coating can be vaporized, an upper portion of the protection element can be treated with a suitable gas, typically carbon for carbidizing or nitrogen for nitrating. Irrespective of the way chosen to achieve the desired effect, it is a relatively small element that is to go through a process for providing sufficient wear strength for the protection element that is to prevent wear on the relatively much larger wearing-part attach- ment.

In a first aspect, the invention relates more specifically to a protection element for a wearing-part attachment for a wearing part for a leading edge of a working member, the wearing part and the wearing-part attachment being provided with complementary quick-coupling elements, characterized by a leading side surface of the protection element including a wearing portion and being arranged, by the engagement of an attachment portion with at least the quick-coupling elements of the wearing part, to rest supportedly against a leading end face of the wearing-part attachment.

The protection element may be formed as a plate in which the wearing portion is arranged at a distance from the attachment portion.

The protection element may be formed as a plate, in which the attachment portion is provided with notches and/or projecting portions complementary to the cross-sectional shape of the quick-coupling elements.

The wearing portion may be taken from a group consisting of a plate element fixed to a plate by soldering or gluing, a coating applied to the plate in vapour form and an upper plate portion with a molecular structure in which a hardness-increasing substance has been added.

The plate element may be formed from carbide steel. The plate element may be formed from ceramics.

In a second aspect, the invention relates more specifically to a method of wear- protecting a wearing-part attachment for a wearing part for a leading edge of a working member, the wearing part and the wearing-part attachment being provided with complementary quick-coupling elements, characterized by the method including the following steps:

bringing a protection element into engagement between quick-coupling sockets at a rear wearing-part portion of the wearing part;

connecting the wearing part and the wearing-part attachment to each other; and

placing the protection element supportedly against a leading end face and so that it projects above a plane coinciding with a top surface of the wearing-part attachment.

In what follows, an example of a preferred embodiment is described, which is visual- ized in the accompanying drawings, in which :

Figure 1 shows, in perspective, a leading portion of a working member, shown here as a cultivator tine, in which a leading end face of a wearing-part attachment is shielded by a protection element according to the invention;

Figure 2 shows a front view of the leading portion of the working member;

Figure 3 shows, on a larger scale, a longitudinal section III-III according to figure

2 through the leading portion of the working member; and

Figure 4 shows a cross section IV-IV according to figure 3 through the wearing part.

In the figures, the reference numeral 1 indicates a leading portion of a working member, illustrated here as a cultivator tine, provided with a wearing part 11 arranged on a leading edge of the working member 1. The wearing part 11 is provided with a quick-coupling holder 111 including quick-coupling elements 112 (see figure 4 in particular), shown here as ridges forming guide portions for engagement with complementary coupling grooves 122 arranged on a wearing-part attachment 12 which is fixed to the working member with several fixing bolts 123. The wearing-part attachment 13 has a leading end face 121 facing in the working direction of the working member 1 and facing a rear portion 113 of the wearing part 11.

A protection element 13 is arranged between the leading end face 121 of the wearing- part attachment 12 and the rear portion 113 of the wearing part 11. The protection element 13 is formed from a plate 130 forming a wearing portion 135 in an upper portion 133. In the figures, the wearing portion 135 is shown as a plate element 135' fixed to an upper portion 134 of a leading side surface 132 of the plate 130 in a suitable manner known to a person skilled in the art. If made from a metal, for example hard metal (carbide steel or the like), the plate element 135' may be fixed by means of soldering, or, if it is made from a non-metallic material, for example a ceramic material, be fixed by means of an adhesive. The protection element 13 extends higher up than a top surface 124 of the wearing-part attachment 12, so that the top surface 124 lies shielded behind the protection element 13.

In an embodiment not shown, an upper plate portion 133 is coated with a hard metal, for example by vaporing or welding, or treated in such a way that a hardness- increasing substance is added to the molecular structure of the plate portion 133, for example by a supply of carbon in a carbidizing process or nitrogen in a nitrating process.

A lower plate portion forms an attachment portion 131 with a sectional profile 136 complementary to the cross section of the quick-coupling element 112 of the wearing part 11, see figure 4 in particular.

When the wearing part 11 is being attached to the wearing-part attachment 12, the protection element 13 is inserted between the quick-coupling holders 111 of the wearing part 11, so that the sectional profile 136 of the attachment portion 131 engages with the quick-coupling elements 112 of the wearing part 11. Then the wearing part 11 is connected to the wearing-part attachment 12, the protection element 13 then coming to lie in front of the leading end face 121 of the wearing-part attachment 12. In an operative state, the flow of loose mass, for example earth, will push the protection element 13 against the wearing-part attachment 12, and the wearing portion 135 retards the wear on the protection element 13 so that it maintains its protective effect on the wearing-part attachment 12.

The effect has turned out to be surprisingly large, which testing of the protection element 13 provided with a wearing portion 135 only on part of the width of the protection element 13 has shown. While the portion of the top surface 124 that was protected by a plate element 135' showed insignificant wear, the portion of the top surface 124 that was not protected had worn down several millimetres in the course of a few days' use on a plough.