DEVICE FOR MACHINING A WORKPIECE PLATE

Description

[0001] The invention relates to a device for machining a workpiece plate with a rotating tool, with a cooling ring surrounding the tool coaxially to its axis of rotation and connected to a pressure line for a cooling liquid to form a cooling liquid ring directed against the circumference of the tool and with at least one sliding surface for the workpiece formed by the cooling ring and provided in a circumferential section of the cooling liquid ring.

[0002] In order to design a sliding guide for a workpiece plate, in particular for a glass pane, in the machining area of ​​a milling or grinding tool in such a way that, with comparatively simple design means, not only gentle guidance of the workpiece plate can be ensured, but also good cooling of the tool as a prerequisite for high machining performance, it has already been proposed (EP 3 118 144 A2) to use the cooling ring that coaxially surrounds the tool and forms an annular nozzle that is connected to a pressure line for a coolant and is directed radially inwards towards the tool, in a circumferential section as a sliding surface for the workpiece plate, so that a hydraulic cushion can build up between the sliding surface and the workpiece plate through the coolant. The coolant flows radially inwards towards the tool from the hydraulic cushion, which is fed with coolant through an annular channel.In the remaining peripheral area, the coolant is sprayed through the ring nozzle directly against the circumference of the tool, which is thus cooled by a coolant ring. However, with such a design, there is a risk that, at the pressure required to build up a corresponding hydraulic cushion, the flow velocity of the spray ring could lead to surface damage to the workpiece plate due to entrained solid particles, particularly if the workpiece plate has a surface layer sensitive to mechanical impact, as is often the case with glass panes. If the pressure is reduced accordingly to avoid damaging the surface, an insufficient hydraulic cushion must be expected.

[0003] For cooling rotating grinding or milling tools used to machine glass pane edges, it is known (EP 1 413 397 A1) to assign a cooling ring to the rotating tool that is coaxial with the axis of rotation. On its inner side facing the tool, the cooling ring has nozzle holes distributed circumferentially. These holes form an acute angle with the axis of rotation of the tool and are connected to an annular channel of the cooling ring. When coolant is applied to the annular channel, a coolant ring is formed that is directed towards the rotating tool and can be used to dissipate heat from the rotating tool. Since only the formation of a corresponding coolant ring needs to be considered, the flow velocity within the coolant ring can be limited to a level that does not pose a risk to the workpiece surface.

[0004] The invention is therefore based on the object of designing a device for machining a workpiece plate with a rotating tool in such a way that, with the aid of the cooling liquid, both a gentle sliding guide for the workpiece plate and an effective cooling of the rotating tool can be achieved without endangering the workpiece surface.

[0005] Starting from a device of the type described at the outset, the invention achieves the stated object in that the cooling ring has spray channels distributed over its circumference, aligned against the circumference of the tool, opening into the sliding surface in the sliding surface area, which are each connected by a throttle to an annular channel connected to the pressure line for the cooling liquid.

[0006] By breaking down the conventional annular nozzle into a ring of individual spray channels directed toward the tool circumference, each connected to the annular channel by a throttle, it is possible to ensure an application pressure for the individual spray channels that is largely independent of the flow conditions in the area of ​​the other spray channels, because the throttles essentially determine the flow distribution to the individual flow channels. This means that the flow velocity in the spray channels can also be reduced by selecting the appropriate flow cross-section without compromising the stability of the hydraulic cushions in the area of ​​the sliding surface for the workpiece plate.

[0007] Particularly favorable connection conditions for the individual spray channels to the common annular channel are achieved when chambers accommodating the throttles are provided between the spray channels and the annular channel, from which the spray channels originate. Under these design conditions, the flow velocity in the spray channels depends significantly on the fluid pressure in the chambers. Particularly simple design conditions can be achieved in this context by having the axes of the chambers, which are designed as bores, run parallel to the tool's rotational axis.

[0008] The drawing shows an example of the subject matter of the invention. Fig. 1 shows a device according to the invention for machining a workpiece plate in a front view, Fig. 2 shows this device in a section along the line II-II of Fig. 1 on a larger scale and Fig. 3 shows a detail of the device in the area of ​​a spray channel in an axial section on a larger scale.

[0009] A device according to the invention for machining a workpiece plate 1, in this embodiment a glass pane, has a tool 3 mounted on a drive shaft 2 for machining a plate edge 4, for example by grinding or milling. A frame 5 accommodating the tool 3 and its drive supports a cooling ring 6 enclosing the tool 3, coaxial with the drive shaft 2 and thus with the rotation axis, which has a ring of spray channels 7 that are inclined radially inward toward the circumference of the tool 3 and open into a flat annular surface 8 on the end face of the cooling ring 6. This annular surface 8 forms a guide segment with a sliding surface 9 for the workpiece plate 1 on the engagement side of the tool 3.

[0010] To supply the spray channels 7 with a coolant, the cooling ring 6 has an annular channel 10, which is connected to a pressure line for the coolant via a connection 11. The spray channels 7 are each connected to the annular channel 10 by throttles 12, which are inserted into chambers 13 from which the flow channels 7 originate. If the chambers 13 are formed by blind bores parallel to the drive shaft 2 of the tool 3, which intersect the spray channels 7, which are preferably also designed as blind bores, simple design relationships result, with the aid of which the required flow conditions can be advantageously taken into account.

[0011] When coolant is applied to the annular channel 10, the coolant flows from the annular channel 10 through the throttles 12 into the chambers 13 and from there through the spray channels 7 to form a coolant ring surrounding the tool 3 and directed towards its circumference. While the coolant can flow unhindered from the individual spray channels 7 outside the sliding surface 9 of the guide segment, forming spray cones that merge into a spray ring, the workpiece plate 1 causes a hydraulic cushion to build up in the area of ​​the guide segment between the sliding surface 9 and the workpiece plate 1, which ensures gentle sliding guidance of the workpiece plate 1 along the guide segment of the cooling ring 6. The coolant emerging radially inward from the gap between the sliding surface 9 and the workpiece plate 1 in turn reaches the tool 3, which is thus also cooled directly in the engagement area.

[0012] Due to the throttling effect of the throttles 12, a largely uniform liquid pressure can be ensured in the chambers 13, which reduces the flow velocity in the individual spray channels 7 and thus ensures gentle treatment of the workpiece surface by the liquid spray ring, especially since the flow cross section of the spray channels 7 can be selected to be correspondingly large, without running the risk of the hydraulic cushion between the sliding surface 9 of the guide segment of the cooling ring 6 and the workpiece plate 1 being reduced.

[0013] A device according to the invention is by no means limited to the formation of a single ring of spray channels 7. Thus, if necessary, further spray channel rings can be provided or merely additional spray channels 14 can be provided in areas of concentric ring sectors 15, which in turn can form sliding surfaces for the workpiece plate 1 to build up corresponding hydraulic cushions, as shown in the Fig. 1 and 2 As shown. Of course, these additional spray channels 14 must also be connected to the annular channel 10 or to a separate distribution channel that can be supplied with coolant by means of throttles 12. A consistent connection structure for all spray channels 7, 14 using a chamber 13 is recommended.

Claims

1. Device for machining a workpiece plate (1) with a rotating tool (3), with a cooling ring (6) surrounding the tool (3) coaxially to its axis of rotation and the cooling ring (6) being connected to a pressure line for a cooling liquid to form a cooling liquid crown directed towards the circumference of the tool (3) and with at least one sliding surface (9) for the workpiece plate (1) formed by the cooling ring (6), provided in a circumferential section of the cooling liquid crown for the workpiece plate (1), characterized in that the cooling ring (6) has spray channels (7, 14) which are distributed over its circumference, are aligned towards the circumference of the tool (3) and open out in the sliding surface region in the sliding surface (9) and are each connected by a throttle (12) to an annular channel (10) which is connected to the pressure line for the cooling liquid.

2. Device according to claim 1, characterized in that chambers (13) receiving the throttles (12) are provided between the spray channels (7, 14) and the annular channel (10), from which the spray channels (7) extend.

3. Device according to claim 2, characterized in that the axes of the chambers (13) formed as bores run parallel to the axis of rotation of the tool (3).