Previously is known a three-part slider element of a zip fastener, where the body, pull tag and spring may be relatively easily assembled into a slider element which locks automatically due to the spring effect so as to become non-sliding, when the pull tag is not pulled ("3-piece auto-lock'). Pulling this pull tag bends the spring and pulls the slide-locking projection out of the tunnel of rows of coupling elements. This solution does not necessarily require complex assembling machinery because it is built up by means of its spring effect and the bevels in the body. A weakness of this solution is, however, the scraping effect of the edges of the spring member. In addition, the spikes of the spring member constitute a weak part that breaks when the slider element is stressed. Also the spring formed as the tail of the spring member is weak and susceptible to breakdowns. The solution functions only in metallic form, when the spring is tempered.

In addition is known a zip fastener slider element of the above-mentioned type (a so-called cam-lock solution), in which the spring effect affects the turning of the pull tag, that is, there is a cam on the pull tag, which bends the spring when the pull tag is turned and at the same time lifts the slide- locking projection connected to the spring up from the tunnel. In the spring are the lugs of the fastening and a pivoting axis of the pull tag, and the

spring for its part is fixed to the body with lugs that must be bent during assembly. This requires an assembling machine.

The aim of the invention is to provide a slider element of a zip fastener of the above type that is easy to assemble (even manually) and which is structurally strong, especially in such a way that the spring and pull tag are tightly locked to the body.

This aim is achieved by means of the invention, on the basis of the characteristics disclosed in claim 1.

A particular advantage of the solution according to the invention is that as the load increases, the curved spring fixed at both ends bites even more tightly into its notches. The slider element in the solution according to the invention (including the spring) may be of metal or plastic. The slider element according to the invention may be of the cam-lock or auto-lock type.

The solution is cheap and simple and does not have the scraping surfaces of a spring member.

The dependent claims disclose preferred embodiments of the invention.

An embodiment of the invention is described in greater detail in the following, with reference to the accompanying drawings, in which Figure 1 shows a slider element of a zip fastener according to the invention, as seen from the side, Figure 2 shows the same slider element when the spring is detached, and Figures 3-6 show the spring from the side, from above, as a section V-V and when spread out. In this case, the spring is a tempered steel

spring. If the spring is made of plastic, it is completed into its final form, and there is no spread-out form as shown in Figure 6.

In the body 1 of the slider element is a tunnel 1.1 for the rows of coupling elements of the zip fastener. The top and bottom parts of the body are joined together by means of a core part 1. 2, which divides one end of the tunnel 1.1 into two tunnel branches, in which the rows of coupling elements separated by the core part 1.2 slide when the zip fastener is being opened or closed. Since the body 1 causes the rows of coupling elements to open and close, the body 1 is also called a lock. The slider element also comprises a pull tag 2 and a spring 3, which locks the pull tag 2 to the body in a manner described in greater detail below. The spring 3 is provided with a slide- locking projection 3.3, which returns to the slide-locking position extending into the tunnel 1.1 due to the spring effect of the spring 3.

At opposite ends of the spring 3 are formed gripping parts 3.1, by means of which the detached, curved spring 3 can be attached to the formed counterparts 1.5. These formed counterparts 1.5 are located at opposite ends of the lugs 1.3 on top of the body. The ends of the lugs 1.3 are formed into guiding arcs that distance the formed gripping parts 3.1 of the spring 3 against the spring force, that is, straighten the curvature of the spring 3 when the spring 3 is pressed into place in the body between the lugs 1.3 from above, until the formed gripping parts 3.1 snap into the formed counterparts 1.5 due to the spring effect of the spring 3. In the case described, the formed gripping parts 3.1 are pins or similar projections at opposite ends of the spring 3, and the formed counterparts 1.5 are notches opening in opposite directions into which the pins 3.1 snap in place. When a spring 3 in position is loaded by pulling it upwards, the gripping pins 3.1 bite even more tightly into the notches 1.5.

In the lugs 1. 3 of the body is an upwards open notch 1.6 which is connected a notch 1. 4 open on one side which receives the fastening and a pivoting axis 2.1 of the pull tag 2. The open side of the notch 1.4 is closed by a branch 3.2 projecting from the spring 3. In the case shown, the slide-locking projection 3.3 is an extension of the branch 3.2 of the spring. The branch 3.2 of the spring thus locks the fastening and a pivoting axis of the pull tag into place by closing the notch 1.4 and by thus preventing the movement of the fastening and pivoting axis 2.1 in the longitudinal direction of the tunnel 1.1 with respect to the body 1. When the shaft 2.1 is locked into place in this manner, there must be a cam 2.2 in connection with the pull tag 2 shaft 2.1, which arches the spring 3 between its fastening ends 3.1 when the pull tag 2 is turned. When the pull tag 2 points in the direction of movement of the slider element 1 for opening the zip fastener, the cam 2.2 allows the spring 3 to return to the rest position, in which the projection 3.3 extends into the tunnel 1.1 through the hole 1.7. When the pull tag 2 is turned into the position shown by the line of dots and dashes in Figure 1, the cam 2.2 will bend the spring 3 by reducing the curvature of the spring arches. The same projection 3.3 also rises up from the tunnel 1.1, whereby the slider element is able to slide to open or close the zip fastener. On the top surface, that is the cover, of the body 1 is a recess 1.8 which receives the cam 2.2. The hole 1.7 is at the bottom of the recess 1.8.

In the case described, the spring 3 is designed in such a way that adjacent to both its fastening ends 3.1 are arches in one direction, and between these arches there is curvature in the spring in the opposite direction. The last- mentioned curvature is at the branch 3.2 and at the projection 3.3. The cam 2.2 bends the spring 3 by reducing the curvature of these arches, that is, three separate arches form what is closer to one large uniform arch. The spring is, therefore, subjected simultaneously to bending stress and tensile stress when the pull tag is pulled or when the pull tag is turned.

Simultaneous bending and tensile stress provide many advantages. The

tension fixes the formed gripping parts 3.1 even more tightly into place.

Materials-even plastic material-withstand tension well. This solution offers for the first time the possibility of making the spring 3 of plastic.

The embodiment described above is thus of the cam-lock type. An auto-lock type solution is realised in such a way that the fastening and pivoting axis 2.1 is not locked into place but is able to move in the notches of the lugs 1.3 against the spring 3, whereby when the pull tag 2 is pulled, the spring 3 bends and is subjected, with its part between the formed gripping parts 3.1, to the bending and tensile stress in the same way as when lifted by the cam 2.2. In this embodiment, the tensile stress of the spring 3 has the additional significance that it receives excessive loads directed at the pull tag and thus substantially reduces the risk of damage.