JPS6052232A - Method and device for separating work from clamping block - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention is a method for separating a workpiece from a cast or injection-molded clamping block, in order to hold the workpiece free from stress during machining on a machine tool. The workpiece is partially buried in the tightening block to form the workpiece and the tightening block into one tightening unit, and at this time, the coefficient of thermal expansion of the tightening Glock material is made to be similar to the coefficient of thermal expansion of the workpiece material. It also concerns the type of setting and the apparatus for carrying out the entire method.

In order to prevent the workpiece on a machine tool, especially the workpiece to be ground on a grinding machine, from being subjected to mechanical load and deformation during machining, the workpiece is cast into a clamping block, and this block It is known that these act as auxiliary members in the clamping and positioning of the workpiece, ensuring that the workpiece is held sufficiently stress-free during all machining operations. The clamping block and the workpiece cast into the clamping block for machining together form a clamping unit. For the production of this clamping unit, the workpiece is placed in a mold, and this mold is subsequently cast together with the material of the clamping block. The material of the tightening block is selected such that its coefficient of thermal expansion is greater than that of the workpiece'@eyebrow. As the clamping block material P), initially fluid, cools in the mold, the clamping block is therefore shrink-fitted onto the workpiece, so that the workpiece is held firmly in the clamping block without any play. In this case, the surface of the workpiece to be machined is located outside the clamping block. A typical example of a turbine blade prepared in this way for machining in a grinding machine is a nickel-based alloy as a material for the turbine blade that meets the high requirements.

The material for manufacturing the clamping blocks that hold the turbine blades is considered to be zinc or zinc alloys, the coefficient of thermal expansion of which is much higher than that of the nickel-based alloys used for manufacturing the turbine blades. , so that when the clamping block is cooled from the casting temperature to room temperature, it is firmly fitted onto the turbine blade.

Particularly problematic is the process of separating the workpiece from the clamping block. For this purpose, according to German Patent Application No. 28 22 828, the tensioning block is
It has a shape that allows it to be created in two along the special break point. For this purpose, a mechanical load is applied to predetermined locations of the tensioning block to divide the tensioning block. The disadvantage of this approach is that the action of the mechanical load in question may not necessarily be limited to the clamping block, and therefore the workpiece held within the clamping block may also be loaded and subject to unfavorable deformation. That's true. Especially in the case of easily damaged workpieces such as turbine blades (keys), the deformation described above can lead to defective products even within a range of 1/1000th of a millimeter.

Furthermore, the pressure required to split the clamping block in half and the relative movement that occurs during the splitting causes material from the clamping block to be transferred and retained on the workpiece, thereby making it difficult to clean or remove the workpiece after cleaning. Additional processing will be required.

Problems to be Solved by the Invention The present invention solves the problems in the above-mentioned known separation methods of loading the workpiece, resulting in deformation, and transfer of the clamping block material to the workpiece, and The object of the present invention is to provide a method and a device that allow a workpiece cast into a clamping block to be separated from the clamping block without residue and without mechanical loads deforming the workpiece.

Means (Method) for Solving the Problems The means in the method of "Unexploded DJ" to solve all the above problems is to manufacture the tightening block from a material that becomes brittle at a predetermined material characteristic temperature, and to process the workpiece. Afterwards, the clamping unit is cooled to at least the embrittlement temperature 1 of the clamping block material, and during this cooling, the clamping block is removed from the workpiece using the internal stress generated based on the different thermal expansion coefficients of the clamping block and the workpiece. The goal is to separate them neatly.

When the tightening unit is cooled at the embrittlement temperature of the tightening block 1, the tightening block also contracts strongly with the workpiece, so that there is a high temperature inside the tightening unit that can cause the separation of the block from the workpiece. Mechanical internal stresses are created.

Embodiment (Method) In case the mechanical internal stresses mentioned above are still insufficient for the separation of the clamping block from the workpiece, the invention furthermore provides that the clamping block is cooled to at least a predetermined embrittlement temperature. It has been proposed to apply a mechanical load from the outside to the clamping block to induce the IWffl k from the workpiece. For this purpose, it is sufficient to impact or impact the clamping block cooled to its predetermined embrittlement temperature. It is also possible to form cracks only on the surface of the tightening block that has been cooled to a predetermined embrittlement temperature in order to cause separation from the workpiece. If cooling the tightening unit to the embrittlement temperature of the tightening block is insufficient to separate the block from the workpiece, apply a light external mechanical load to the tightening unit that has been cooled to the embrittlement temperature. , it is sufficient to induce the fraction σ11 (from the workpiece. This makes it possible for the workpiece to undergo the following additions or to be used for a predetermined purpose without modification. The clamping block can be separated from the workpiece without residue by separation at low temperatures.In this case no mechanical loads (which would lead to deformation of the workpiece) occur, since the clamping block is cooled at a given embrittling temperature. This is because the contraction that occurs when the workpiece is removed creates an overall pressure increase on the workpiece.

Is zinc or other material suitable for manufacturing tightening blocks? Zinc alloys are preferred, but other alloys can also be used, such as those based on lead or antimony or tin, which become brittle at low temperatures and have a coefficient of thermal expansion greater than the work material. If the workpiece is a turbine blade,
Since this workpiece is made of nickel or a nickel-based alloy and does not become brittle even at low temperatures, it is advantageous if the workpiece can be cooled down to the temperature without any damage after the isothermal treatment of the clamping unit.

The method according to the invention can be carried out in a fully automated manner. To this end, the present invention automatically transports successive tightening units sequentially from the machine tool to the cooling device after processing the workpiece,
It is proposed to use this cooling device to cool the clamping unit for separation of the clamping block to at least the brittle temperature of the clamping block material, and to transport the clamping block after separation with the workpiece for further processing. .

Means (device) for solving the problem is assigned a material, by means of which the clamping unit is captured after workpiece machining operations in the machine tool and is transported (generally) into a cooling device and at least The workpiece is removed from the cooling device after it has been cooled down to the embrittling temperature of the clamping block material.

If the materials of the clamping block and the workpiece are selected in such a way that the internal stresses that arise during their cooling are sufficient for the separation of the clamping block from the workpiece, the clamping block with the workpiece is generally already connected to the cooling device. can be clearly separated within the In this case, only the workpieces released from their clamping blocks are removed from the cooling device. Each separated clamping block is then separately removed from the cooling device and optionally supplied for reuse.

Embodiment (Apparatus) In some cases, the internal stresses generated in the clamping block during cooling may not be sufficient to cause automatic separation of the workpieces. For such cases, the invention provides that the cooling device is cooled to at least the brittle temperature in the cooling device or behind it.
A part for mechanically applying a load to the tightening lever.
It is preferable that a movable bolt 1'A be provided in the transport path of the cooled tightening unit.
It can be formed as a tool. The abutment may also be formed as an edge, at which the part plunges into the transport path of the cooled tightening unit, so that the tightening unit removed from the cooling device abuts against the edge. Being hit,
As a result, the clamping block is separated from the workpiece. Furthermore, according to the invention, a tool can be provided as an abutting element for causing cracks in the surface of the cooled tightening unit.

A cooling bath filled with liquid nitrogen is advantageously provided as a cooling device.

Embodiment In FIG. 1, a conventional grinding machine 1 is shown as a machine tool. This grinding machine has on a machine bed 2 a feed base 3 which is slidable in the X direction, and on this feed base 3 a table 4 which is further slidable in the Z direction is supported. This table 4
9 holds a tightening unit 6 in a holder (not shown), and as can be seen from FIG.
It consists of. As this workpiece, a turbine blade is shown in FIG.

The grinding machine 1 has a machine support 9 on which a grinding spindle with a grinding wheel 11 is supported in the Y direction.

According to the invention, a cooling device in the form of a quenching bath 12 is assigned to the grinding machine 1 . Conveying member 1 indicated by chain lines in FIG.
The cutting machine 1 and the quenching bath 12 are connected by 3.

After the quenching bath 12, a movable hammer 14 is arranged in the path of movement of the conveying member 13.

This hammer 14 is arranged on one arm 16 of an angle lever 18 which can be pivoted about an axis 17, and the other arm 19 is connected to an operating member 21 of an electromagnetic drive 22, which is arranged as a controllable operating mechanism. For the machining of a turbine blade (workpiece) 8 in the grinding machine 1, which is pivotally mounted on a clamping block, the workpiece may have the shape shown in FIG. 2 or even other simpler shapes. 7 will be cast. Since the heat shrinkage coefficients of the material of this vane and the material of the tightening lock are compatible, the tightening lock is tightly shrink-fitted onto the turbine blade when the casting temperature is cooled to room temperature. The turbine blades I are tightly clamped into the clamping block. With this tightening block 7, the turbine blade tlyJ
, (d brought into position in the grinding machine 1. After machining the workpiece, i.e. in the row shown; after machining the leg or head of the turbine blade, the clamping unit consisting of the turbine blade 8 and the clamping block 7 6 is removed from the grinding machine 1 and introduced via a conveying member 13 into a quenching bath 12. This quenching bath 12 preferably contains liquid nitrogen having a boiling temperature of -196 DEG C.

The clamping block 7 is then made brittle by cooling the clamping unit 6 to at least the embrittlement temperature of the clamping block material. At the same time, the cooling of this clamping block 7 causes it to further contract and crimp to the north of the turbine blade, which contracts less than the block, thereby creating mechanical internal stresses within the clamping block, which in turn creates a suitable material for the clamping block. If the shape is chosen, this stress can directly lead to the separation of the brittle clamping block 7 from the workpiece 8. Only this turbine blade 8 released from the clamping block 7 is transported out of the quenching bath 12 by the conveying member 13 . This cleanly separated clamping block member, not shown in FIG. 1, is separately removed from the quench bath and supplied for subsequent use.

In case the internal stresses generated in the clamping block γ during cooling are insufficient to loosen it from the turbine blades 8, a hammer 14 formed as a hammer 14 at the rear of the quenching bath 12 is used. A section lIJ is provided. As soon as the tightening unit 6 is cooled down to the brittle temperature of the tightening block material via the quenching bath 12 and reaches the range of the hammer 14, the electromagnetic drive 22 is actuated and the axis 17
By pivoting the fully centered angle lever 18, the hammer 14 is applied against the clamping block γ, which causes the clamping block 7 to crack due to its internal stress. In order to separate the clamping block 7 brought to this low temperature from the turbine blade 8, it is sufficient to lightly apply the damper 14 to the clamping block 7. In this way, it is possible to reliably separate the machined turbine blade 8 from the clamping block in such a way that it can be supplied without the need for further post-processing 1. The clamping block 7 can be removed from the turbine blade without any residue, and the separation of the clamping block 7 does not result in any deformation of the turbine blade.

Effects According to the present invention, it is possible to separate the clamping block from the workpiece without any load. There is no need to worry about the occurrence of deformation of the workpiece during the separation of the tensioning block. Furthermore, the separation of the tensioning block from the workpiece is carried out completely without residue, thus removing any remaining tensioning block material from the workpiece. No post-processing is required.The separated tightening member can be supplied as is for reuse.Furthermore, the device for carrying out the method according to the invention has an extremely simple structure, and the method can be completely carried out. Can be performed automatically.

[Brief explanation of the drawing]

The drawings show an embodiment of the invention, in which FIG. 1 is a schematic diagram of a device according to the invention, and FIG. 2 is a typical clamping unit consisting of a turbine blade as a workpiece and a clamping block. It is a perspective view showing an example. 1...Grinding machine, 2...Machine bed, 3 Feeding table, 4
...Table, 6...Tightening unit, 7...Tightening block, 8...Workpiece, 9...Machine support, 11...
・A iJi grinding wheel, 12...Quiet cooling bath, 13...Transport part A114...Hammer, 16.19...Lever arm, 17...M line, is...Angle lever 121,
・Operation member, 22...electromagnetic drive device

Claims (1)

[Claims] 1. A method for separating a workpiece from a cast or injection-molded clamping block, the workpiece being held in a clamping block in order to hold the workpiece without load during machining on a machine tool. The workpiece and the tightening block are formed into one tightening unit by being partially buried in the workpiece, and at this time, the thermal expansion coefficient of the tightening block material is set to be larger than that of the workpiece material. in which the tightening block is manufactured from a material that becomes brittle at a predetermined material characteristic temperature;
After machining the workpiece, the clamping unit is cooled to at least the embrittling temperature of the clamping block material, and during cooling, the clamping block is removed from the workpiece using the internal stress generated due to the different thermal expansion coefficients of the clamping block and the workpiece. A method for separating a workpiece from a tightening block, characterized by clean separation. 2. The method according to claim 1, wherein a mechanical load is externally applied to the clamping block that has been cooled to at least a predetermined embrittlement temperature to cause separation from the workpiece. 6. Shock-loading the tightening block cooled to at least a predetermined embrittlement temperature by impact or collision;
The method according to claim 2. 4. A method according to claim 2 or 6, characterized in that the surface of the clamping block cooled to at least a predetermined embrittling temperature is characterized by cracks in order to induce separation from the workpiece. 5. The method according to any one of claims 1 to 4, using a clamping block made of zinc or zinc die-casting. 6. A method according to any one of claims 1 to 5, characterized in that the tightening unit is cooled to the temperature of liquid nitrogen. Z After machining the workpiece, successive clamping units are automatically transferred one after another from the machine tool to a cooling device, which cools the clamping units for the clamping block portion: After cooling the workpiece at the brittle temperature and separating the tightening block,
The method according to any one of claims 1 to 6, which is carried out for subsequent processing. 8. A device for separating a workpiece from a cast or injection-molded clamping block, in which the workpiece is partially embedded in the clamping block in order to hold the workpiece without full load during machining on a machine tool. The workpiece and the tightening block are formed into one tightening unit, and in this case, the thermal expansion coefficient of the tightening block material is set larger than the thermal expansion coefficient of the workpiece material. but,
Manufactured from a material that becomes brittle at a given material characteristic temperature, the clamping unit is cooled after machining of the workpiece to at least the embrittlement temperature of the clamping block material, and during this cooling the different thermal expansions of the clamping block and the workpiece are Using the internal stress generated based on the coefficient, the clamping block is assigned the work piece (13) and the conveying member (13) is attached to it.
13) captures said clamping unit (6) after the workpiece machining operation in the machine tool and transports it into the cooling device (12) and after cooling to at least the brittle temperature of the clamping block material, the workpiece (8) A device for separating the workpiece from the tightening block, characterized in that the workpiece is removed from the cooling device (12). 9. Patent claim, in which a support member (14) is arranged in or behind the cooling device (12) for mechanically loading the clamping block (7) cooled to at least the embrittling temperature. The method according to item 8. 10. The method as claimed in claim 9, wherein the applying element is designed as a movable percussion tool (14) in the conveying path of the cooled tightening unit (6). 12. The method according to claim 9, wherein the abutting member is formed integrally with the edge of the cooled tightening unit during transport, and the abutting member plunges into the path. This causes cracks on the surface of the cooled tightening unit (6).
: Claims 9 to 1 are formed in the form of a sea urchin.
The method described in any one of the dimensions. 13. The method according to any one of claims 8 to 12, characterized in that the cooling device (12) is a cooling bath crystallized with liquid nitrogen.