GB2175519A - Device for sharpening a tool - Google Patents

Abstract

A device for sharpening a working tool 1, especially a rotatable wire brush for roughening a lasting margin of a shoe upper, consists of a holder 3 carrying a sharpening element 31 and slidably mounted on a structure 2 supporting the working tool 1. The piston rod 42 of a pressure cylinder 4 is connected to a balance lever 5 pivoted on the holder 3, one arm of which is provided with a pawl 51 adapted for engaging ratchet teeth 24 formed on the structure 2, and to the other arm there is connected a spring 52 anchored to an adjusting screw 53 which is screwed in a bracket 35 on the holder 3, the screw 53 being secured by lock nuts 54. <IMAGE>

Description

SPECIFICATION Device for sharpening a working tool The invention relates to a device for sharpening a working tool, especially a rotating wire brush for roughening a lasting margin of a formed (or tightened) shoe upper, which consists of a holder of a sharpening tool seated in a body of the working tool and connected to a piston rol of a pressure cylinder.

In machines for roughening lasting margins of formed or tightened shoe uppers, there are mostly used rotating wire brushes. In course of operations the ends of individual wires become blunt and that is why it is necessary for the blunt ends of wires ot be sharpened at defined intervals by grinding the whole rotating working surface which is filled by these wires. Such a sharpening is usually performed by means of a grinder, which is pressed against the rotating working surface of the wire brush. After the grinder has been pressed down, it must be locked, for an accurate geometry of the rotating working surface to be achieved by the grinding operation.

There is known a device, the grinding wheel of which is shiftable, guided in a body of the working tool; the shifting movement is derived from the motion of the piston rod of the pressure cylinder.

After shifting the holder towards the rotating working surface of the wire brush, the grinding wheel swings a little back in the holder because of a tangential reaction of the rotating wire brush. The said back swing switches a switch which shifts over a distributor of a pressure medium, and in this way a continuous shift of the piston rod of the pressure cylinder cannot take place. This embodiment provides a disadvantage, namely, a relative complexity, which results in high production costs. Another disadvantage resides in the fact that the pressure cylinder presses the grinding wheel onto the sharpened rotating surface during the whole sharpening operation, which requires an increased power consumption. Moreover the elasticity of the pressure medium does not guarantee a sufficient accuracy of the geometry of the sharpened rotating working surface of the wire brush.

It is an object of this invention to provide a device for sharpening a working tool in which the disadvantages of the described devices of the prior art are eliminated or at least mitigated. The princi ple of the invention resides in the fact that a piston rod of a pressure cylinder is jointed to a balance beam, one arm of which is adapted by a pawl for meshing with ratchet teeth provided in a body of the tool, and to another arm there is connected a spring, which is anchored to a bracket of a holder of a sharpening tool. The spring is anchored to an adjusting screw, which is fixed in the bracket of the holder of the sharpening tool.

An effect of the invention resides in the fact that the pressure cylinder shifts only the holder of the sharpening tool and causes the balance beam to swing into a locking position, a force reaction of the pressing down of the sharpening tool during the sharpening operation is held by the pawl and ratchet teeth. Such an embodiment is reliable and secures a desired accuracy of the geometry of the sharpened rotating working surface of the tool. For shifting the holder of the sharpening tool there may be used a pressure cylinder of only small power consumption. It may be used for the balance beam as well. A desired prestress of the spring can be set up means of the adjusting screw.

In order that the invention may be clearly understood and readily carried into effect, a preferred embodiment thereof is, by way of example, hereinafter more fully described and illustrated in the accompanying drawings showing a longitudinal section of a preferred device embodying the invention in a schematic sketch.

A working tool 1 is seated in a basic or main body 2, which is fixed in a frame (not shown) of a working machine. The working tool takes the form of a wire brush, which is fixed onto a shaft 21 seated in the body 2 and provided with a chain wheel 22. The chain wheel 22 is connected to a not shown diriving unit. A holder 3 of a sharpening tool 31 is shiftably mounted in a guide 23 of the basic body 2. The sharpening tool 31 is formed by a grinding element of a prismatic shape, which is seated in a bush 32 fixed in the holder 3. The bush 32 is provided with a connection 33 for fixing the sharpening tool 31 in the adjusted position. In the basic body 2 there is pivotably mounted a pressure cylinder 4 with a piston 41 and piston rod 42 which is jointed to a balance beam 5.The balance beam 5 is mounted on the holder 3 via a pin 34 and its one arm is provided with a pawl 51 which is adapted for engaging ratchet teeth 24 formed in a guide 23 of the basic body 2. To the other end of the balance beam 5 there is fixed a spring 52 which is anchored to an adjusting screw 53. This adjusting screw 53 is screwed in a bracket 35 and locket by nuts 54. The bracket 35 is fixed in the holder 3.

In the basic position the piston rod 42 is extended from the pressure cylinder 4 to its limit, the holder 3 with the sharpening tool 31 is shifted away in the guide 23 of the basic body 2 from the working tool 1 and the pawl 51 of the balance beam 5 is out of engagement from ratchet teeth 24. If it is needed to perform a sharpening operation, the attending worker of the machine changes over a not shown distributor, through which the pressure medium is supplied behind the piston 41.

Thus the piston rod 42 commences sliding in the pressure cylinder 4. The prestress of the spring 52 is set up by means of the adjusting screw 53 so that its force value is bigger than the value of a frictional resistance to the shifting of the holder 3.

In this way, during the shifting of the piston rod 42, the pawl 51 of the balance beam 5 stays out of engagement from the ratchet teeth 24, and the holder 3 is shifted in the guide 23 of the basic body 2, till the sharpening tool 31 bears against the rotating working surface of the working tool 1.

At this moment there increases a resistance against the shifting of the holder 3 in the guide 23 and its value comes to exceed the value of the prestress of the spring 52. In this way the balance beam 5, because of the continuing shifting of the piston rod 42, pivots around the pin 34 against the action of the spring 52, and its pawl engages one of the ratchet teeth 24 of the guide 23, which corresponds with the length of the part of the sharpening tool 31 protruding out of the bush 32. The shifting of lye holder 3 with the sharpening tool 31 in the guide 23 of the basic body 2 is locked in this way for a time needed for sharpening the working tool 1. The device is shown in this position in the drawings. After the working tool has been sharpened, the attending worker changes over the not shown distributor, and the pressure medium is supplied into the space in front of the piston 41 of the pressure cylinder 4 and in this way the whole device is returned to its initial position again.

The invention may be applied for sharpening a working tool, especially a rotating wire brush for roughening a lasting margin of a formed or tightened shoe upper, as described for example in our co-pending application No. 8607409. (Serial No. 2reference 230P52100).

Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but it is capable of numerous modifications within the scope of the ap-

Claims (2)

pended claims. CLAIMS

1. A device for sharpening a working tool, especially a rotating wire brush, comprising a holder of a sharpening tool mounted on a body of the working tool and connected to a piston rod of a pressure cylinger wherein the piston rod of the pressure cylinder is jointed to a balance beam, one arm of which is adapted for engaging ratchet teeth formed in the body in the working tool, and to another arm there is connected a spring, which is anchored to a bracket of the holder of the sharpening tool.

2. A device as claimed in claim 1, wherein the spring is anchored to an adjusting screw, which is locked in the bracket of the holder of the sharpening tool.