CA2351857C

CA2351857C - Tool assembly with a multi-dimensionally resiliently mounted tool

Info

Publication number: CA2351857C
Application number: CA 2351857
Authority: CA
Inventors: Erwin Rothballer
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-05-19
Filing date: 2001-06-27
Publication date: 2007-04-03
Anticipated expiration: 2021-06-27
Also published as: CA2351857A1; DE20108446U1

Abstract

The invention relates to a tool assembly (1) with a multi-dimensionally spring mounted tool (2) with an elongated blade (8) for the machining of a workpiece by guiding the tool (2) along a workpiece contour to be machined. To improve the machining of workpieces made of resilient materials, it is suggested that the tool assembly (1) comprises oscillation means (11) to enable the tool (2) to perform back and forth movements in a direction that is substantially parallel to the length of the blade (8).

Description

TOOL ASSEMBLY WITH A MULTI-DIMENSIONALLY
Resiliently mounted TOOL
The present invention relates to a tool assembly with a multi-dimensionally resiliently mounted tool provided with an elongated blade for machining a workpiece by guiding the tool along a workpiece contour to be machined.
Such a tool assembly is known, for example, from DE 299 03 312, EP 99 926 268 or US 09/512,365. Specific reference is made to the above named published prior art. The tool assembly disclosed in these publications concerns a tool that is movable on several planes. The tool is designed as a deburring cutter for deburring resilient or soft workpieces, especially those of plastic or rubber. The deburring cutter is rotatingly resiliently mounted about its longitudinal axis in the tool assembly. The longitudinal axis of the deburring cutter is arranged at a distance from the longitudinal axis of the tool assembly. In addition, the deburring cutter is rotationally resiliently mounted about the longitudinal axis of the took assembly.
The tool assembly known in prior art has proven very successful in practical applications, in particular in the deburring of moulded articles immediately after mould release. Moulded articles of plastic or rubber are subjected to cooling after mould release. To shorten the turnaround time, deburring of moulded articles is started immediately after mould release. Cooling of the workpiece results in an intensive shrinking of the workpiece during the deburring process. The shrinking dimensions of the workpiece can be compensated without problem with the tool assembly known in prior art because the tool is multi-dimensionally resiliently mounted.
The objective of the present invention is to design and further develop a tool assembly of the type mentioned above to further improve the machining of workpieces made of resilient materials.

The invention achieves this objective, starting out from the tool assembly of the type mentioned above, by creating a tool assembly which includes oscillation means allowing the tool to move back and forth in a direction that is substantially parallel to the length of the blade.
With the tool assembly according to the invention, even workpieces made of a resilient material such as fabric or leather can be machined without problem. The tool assembly can be used for the quick and accurate removal of residual pieces of fabric or leather from shoes or clothing.
The back and forth movements of the tool across the guiding direction of the tool and parallel to the length of the blade clearly improve the cutting accuracy of the tool, and in particular, they also clearly reduce the pressure required in pilot direction. This means that even workpieces of resilient materials, which produce very little or no back pressure, can be machined without problem. The tool can be guided much more quickly and accurately along the workpiece contour to be machined.
In accordance with an advantageous further development of the present invention, it is suggested that the oscillation means move the tool into a linear lifting movement which runs substantially parallel to the length of the blade.
The cutting pressure can be further reduced in accordance with another advantageous further development of the present invention, in which the oscillation means additionally move the tool into a pendulum movement that runs substantially parallel to the pilot direction of the tool.
Another reduction of the cutting pressure can be achieved by means of another advantageous further development of the present invention, where the oscillation means enable the tool to perform a lifting movement and in addition a pendulum movement whose direction is substantially parallel to the pilot direction of the tool. Thus, the tool performs a lifting / pendulum movement.
According to a preferred embodiment of the present invention, it is suggested that the tool be designed as a deburring cutter for deburring the workpiece along the contour.
Preferably, the lifting or lifting / pendulum movement has a frequency of more than 10 Hertz. Thus, the tool performs at least 10 full back and forth movements per second. Preferably, the lifting movement or lifting /
pendulum movement has a frequency of about 100 Hertz.
The lifting movement or lifting / pendulum movement is particularly easy to produce if the oscillation means are designed as an electric oscillator which causes the lifting movement or the lifting / pendulum movement of the tool.
Preferably, the tool is fastened to the tool assembly by a tool receptacle.
The oscillating means are linked to the tool receptacle. The tool receptacle is mounted in the tool assembly in such a way that an activation of the oscillation means caused the lifting movement or lifting / pendulum movement of the tool assembly with the tool.
According to an alternative embodiment, it is suggested to design the oscillation means as a hydraulically or pneumatically operated valve arrangement which causes the lifting movement or lifting / pendulum movement of the tool. By means of a hydraulic or pneumatic valve arrangement, it is also possible to achieve relatively great lifts and high mechanical frequencies.
In accordance with one preferred embodiment of the present invention, it is suggested that the valve arrangement be provided with a cylinder with a differential pressure piston which can be connected to the tool, for example via the tool receptacle, whereby pressure chambers charged with different pressures are formed in the cylinder on both sides of the plunger. The back and forth movement of the differential pressure plunger in the cylinder is caused when the pressure applied in the pressure chambers is alternatively increased and decreased. The movement of the differential pressure plunger is transferred to the tool which performs a lifting movement or a / pendulum movement as the result. The cylinder is arranged in the tool assembly. The variable pressures for charging the pressure chambers of the cylinder can also be produced in the tool assembly by suitable means, or they can be supplied to the cylinder from outside the tool assembly.
Advantageously, the valve arrangement is provided with two 5 / 2-way valves connected back to back, whereby the variable pressures are applied at the outputs of one of the two 5 / 2-way valves for charging the pressure chambers of the cylinder. Each output of the two 5 / 2-way valves is connected to actuating connections of the other 5 / 2-way valve. In this manner, a flip flop function can be achieved hydraulically or pneumatically.
Preferably, each of the actuator connections on one of the two 5 / 2-way valves is provided with an adjustable throttle for adjusting the frequency or maximum deflection of the lifting movement or lifting / pendulum movement. With the adjustable throttles, the tool assembly can be optimally adapted to workpieces made of different materials.
Finally, it is suggested that the oscillation means are provided with an eccentric cam rotatably mounted in the tool assembly, in which the tool is eccentrically mounted, whereby the tool is resiliently mounted in the tool assembly at a distance from the eccentric mounting. When the oscillation means are of such design, they allow the tool in a particularly simple manner to perform a lifting / pendulum movement.
In accordance with another advantageous further development of the present invention, it is suggested that at least one force and torque sensor be provided between the tool and the guidance means of the tool assembly for guiding the tool along the workpiece contour. The force and torque sensors can measure forces and torques which act between the tool and the guidance means, while the tool is guided along the workpiece contour to be machined. Depending on the kind of workpiece to be machined, the forces and torques should be within a range that can be preset. If they are too high, this could be a sign that the bearing pressure of the tool on the workpiece is too high. If the forces and/or torques are too low, this could be a sign that the pressure of the tool on the workpiece is too low or that the tool is not even touching the workpiece at all. With the help of the force and torque sensors, the bearing pressure of the tool on the workpiece can be exactly monitored or perhaps even adjusted during machining.
The tool assembly according to this further development is also preferably provided with oscillation means to cause a lifting movement or lifting /
pendulum movement. However, the tool assembly with at least one force and torque sensor has the above mentioned advantages even without the characteristics described in Claim 1. Protection under the present patent is therefore also to extend to tool assemblies of the latter kind, which are lacking the characteristics described in the generic part of Claim 1.
In accordance with a preferred embodiment of the present invention, it is suggested to provide means to calculate drive signals for the guidance means of the tool assembly which depend on output signals of at least one force and torque sensor. The guidance means are designed, for example, as a handling device, in particular as an industrial robot, in which case the tool assembly is fastened to the end effector of the robot arm. The means of calculating drive signals are part of a drive for the robot. The output signals of the force and torque sensors are taken into account when the drive signals are calculated as part of a control or regulating system. In this manner, the tool can be guided with a constant bearing pressure along a workpiece contour to be machined.
Further characteristics, applications and advantages of the invention become apparent in the following description of embodiments of the invention shown in the drawings. All described or shown characteristics constitute the subject of the invention separately as well as in any combination, regardless of how they are summarized in the claims or references thereto and regardless of their formulation in the description or their presentation in the drawings, in which Figure 1 shows a preferred embodiment of the tool assembly according to the invention;
Figure 2 shows a valve arrangement for the tool assembly shown in Fig.
1, in a first position;
Figure 3 shows the valve arrangement shown in Fig. 2, in a second position;
Figure 4 shows the course of a lifting movement of a tool of the tool assembly shown in Fig. 1, and Figure 5 shows a tool assembly according to the invention, with a force and torque sensor.
In Fig. 1, an entire tool assembly according to the invention is referred to as number 1. Tool assembly 1 comprises a multi-dimensionally resiliently mounted tool 2. Tool 2 is rotatably mounted in a tool receptacle 3 about a longitudinal axis 4 of tool 2. The rotational movement of tool 2 about the longitudinal axis 4 is indicated by arrow 5. Tool 2 is arranged eccentrically in tool assembly 3, i.e. at a distance from a longitudinal axis 6 of tool receptacle 3. Tool receptacle 3 is rotatable about longitudinal axis 6 together with tool 2. This rotational movement is indicated by double arrow 7. Such a tool assembly with a multi-dimensionally resiliently mounted tool is known, for example, from DE 299 03 312, EP 99 926 268 or US
09/512,365. Specific reference is made to the above named published prior art. In addition, the tool can also be movable in other directions or about other rotational axes.
Tool 2 comprises an elongated blade 8 for machining a workpiece. For this purpose, tool 2 is guided in the direction of arrow 9 along a workpiece _7_ contour to be machined. For that purpose, tool 2 is guided in the direction of arrow 9 along a workpiece contour to be machined. Tool 2 is designed as a debarring cutter for debarring the workpiece along the contour. Any handling device can be used to guide tool 2, including an industrial robot, in which case tool assembly 1 would be fastened to an end effector 10 of a robot arm.
According to the invention, tool assembly 1 is provided with oscillation means 1 1 to enable tool 2 to perform a back and forth lifting movement 12, at least during machining of the workpiece, in a direction that is substantially parallel to the length of blade 8. In addition, the oscillation means 1 1 can also enable tool 2 to perform a back and forth pendulum movement 13 in a direction that is substantially parallel to pilot direction 9 of tool 2, so that the overall result is a lifting / pendulum movement.
Through lifting movement 12 and lifting / pendulum movement 12, 13, the pressure that must be applied to tool 2 in pilot direction 9 for the machining of the workpiece can be clearly reduced. Thus, it is possible for the first time to cut/machine workpieces made of very flexible materials such as fabric or leather. The oscillation means 1 1 are connected to tool 2 via coupling elements 14, a tool holder 15 and tool receptacle 3. The oscillation means are firmly connected to a housing 16 of tool assembly 1. The tool holder 15 is fully floating in housing 16. As an alternative, it is also conceivable to design the oscillation means 1 1 in such a way that they act immediately upon tool holder 15, tool receptacle 3 or tool 2.
It is conceivable that the oscillation means 1 1 could be operated electrically.
This could be achieved, for example, with an electromagnet, whose armature is mechanically connected to tool 2 and which is charged with a voltage of cyclically alternating polarity.
However, an especially high lifts and a high mechanical frequency of lifting movement 12 or lifting / pendulum movement 12, 13 can be achieved if the oscillation means 11 are activated pneumatically or hydraulically. Figures 2 and 3 show a valve arrangement (referred to as number 17) with oscillation means 1 1 that can be pneumatically activated. This valve arrangement 17 comprises a pneumatic cylinder 18 with a differential pressure plunger 19 that is connected to tool 2. On both sides of plunger 19 in cylinder 18, pressure chambers 20, 21 are formed to which different pressures p1 and p2 can be applied. If pressure p2 is greater than pressure p1, plunger 19 moves to the left in the direction of an arrow 22 (see Fig. 2). If pressure p1 is greater than pressure p2, plunger 19 moves to the right in the direction of arrow 23 (see Fig. 3). By alternately increasing and decreasing pressures p1 and p2, piston 19 and thus also tool 2 can be enabled to perform a back and forth lifting movement 12.
The cyclically changing pressures p1 and p2 are produced by two 5 / 2-way valves 24 and 25 connected back to back. To explain the function of valve arrangement 17, reference is made to the position of the 5 / 2-way valves 24 and 25 in the position shown in Fig. 2. A constant pressure p3 is applied to inputs P of the 5 / 2-way valves, which is led to exits B. Output B of second 5 / 2-way valve 25 is connected to a left-hand actuating connection 26 of first 5 / 2-way valve 25. A right-hand actuating connection 27 of first 5 / 2-way valve 24 is connected to an output A of second 5 / 2-way valve 25 and ends in a first air outlet connection R1 of second 5 / 2-way valve 25, First 5 / 2-way valve 24 is therefore pushed to the right by the pressures applied to actuating connections 26 and 27 (see Fig. 2).
Outlet B of the first 5 / 2-way valve 24 is connected to a second actuating connection 29 of second 5 / 2-way valve 25. A first actuating connection 28 of second 5 / 2-way valve 25 is connected to an output A of first 5 / 2-way valve 24 and ends in air outlet connection R1. The pressures applied to actuating connections 28 and 29 of second 5 / 2-way valve 25 cause valve 25 to perform an actuating movement toward the left into the position shown in Fig. 3. Now, constant pressure p3 is applied to output A of second 5 / 2-way valve 25 and is led to second actuating connection 27 of first 5 / 2-way valve 24. The first actuating connection 26 of first 5 / 2-way _g_ valve 24 is connected to air outlet connection R2 via output B of second 5 /
2-way valve 25. This also causes the first 5 / 2-way valve 24 to move left from the position shown in Fig. 2 to the position shown in Fig. 3.
In turn, the position of first 5 / 2-way valve 24 shown in Fig. 3 has the effect that a higher pressure is applied to first actuating connection of second 5 / 2-way valve 25 than to the second actuating connection 29, so that the second 5 / 2-way valve 25 is moved from the position shown in Fig. 3 back to the right into the position shown in Fig. 2. Thus, the two 5 /
2-way valves 24 and 25 are connected back to back in such a way that they perform a constant back and forth movement when constant pressure p3 is applied. In the position of first 5 / 2-way valve 24 shown in Fig. 2, pressure p2 is greater than pressure p1. However, in the position of first 5 /
2-way valve 24 shown in Fig. 3, pressure p1 is greater than pressure p2.
This means that valve arrangement 17 can enable tool 2 to perform a constant lifting movement. Fig. 4 shows the path of lift h over time t. It is clearly distinguishable that lift h follows a saw-tooth type of path. Angle a, which determines the steepness of the lift and thus also the frequency of the lifting movement, can be varied with an adjustable throttle 30 which is connected to the first actuating connection 26 of first 5 / 2-way valve 24.
Furthermore, the maximum deflection hmaX of the lifting movement can be varied with a second adjustable throttle 31 which is connected to the second actuating connection 27 of first 5 / 2-way valve 24.
Fig. 5 shows another preferred embodiment of tool assembly 1 according to the invention. In this embodiment, a force and torque sensor 33 is arranged between tool 2 and the industrial robot or, to be more precise, between tool assembly 15 and end effector 10 of the robot arm. The forces and torques acting upon tool 2 during the machining process are transferred to force and torque sensor 33 via tool receptacle 3, tool holder 15 and the force and torque transfer means 32. The output signals of the force and torque sensor are taken into account by a control system of the industrial robot when the control signals for the adjusting elements of the robot are calculated so that tool 2 is pushed against the workpiece at a constant bearing pressure during the machining process. The bearing pressure can be controlled and/or regulated by the control system of the industrial robot. The embodiment of tool assembly 1 shown in Fig. 5 may also be provided with oscillation means 1 1 which enable tool 2 to perform a lifting movement 12 or a lifting /
pendulum movement 13.

Claims

1. Tool assembly (1) with a multi-dimensionally resiliently mounted tool (2) with an elongated blade (8) for the machining of a workpiece by guiding the tool along a workpiece contour to be machined, characterized in that the tool assembly (1) comprises oscillation means (11) coupled with the tool (2), which are supported within a tool holder (15), that the oscillation means operates the tool in a combined lifting and pendulum movement in a pilot direction (arrow 9), and that the tool holder is floatingly supported within a housing (16), whereby the axis (4) of the tool (2) is eccentrically arranged relative to the axis (6) of the tool holder (3).

2. Tool assembly (1) according to claim 1, characterized in that tool (2) is a deburring cutter.

3. Tool assembly (1) according to claims 1 or 2, characterized in that the lifting and pendulum movement (13) has a frequency of more than 10 Hz.

4. Tool assembly (1) according to claim 3, characterized in that the lifting movement or lifting and pendulum movement (13) has a frequency of about 100 Hz.

5. Tool assembly (1) according to any one of claims 1 - 4, characterized in that the oscillation means (11) is an electrical oscillator which drives the tool (2) into a lifting and pendulum movement (13).

6. Tool assembly (1) according to any one of claims 1 - 4, characterized in that the oscillation means (11) is a hydraulically or pneumatically powered valve arrangement (17) which drives the tool (2) into a lifting and pendulum movement (13).

7. Tool assembly (1) according to claim 6, characterized in that the valve arrangement (17) is provided with a cylinder (18) with a differential pressure plunger (19) which is connected to the tool (2), whereby pressure chambers (20, 21) to which variable pressures (p1, p2) can be applied, are formed in the cylinder (18) on both sides of the plunger (19).

8. Tool assembly (1) according to claim 7, characterized in that the valve arrangement (17) is provided with two 5/2-way valves (24, 25) connected back to back, whereby the variable pressures (p1, p2) are applied to the outputs (A, B) of any one of two 5/2-way valves to charge the pressure chambers (20, 21) of the cylinder (18).

9. Tool assembly (1 ) according to claim 8, characterized in that the actuating connections (26, 27) of one 5/2-way valve (24) are each provided with an adjustable throttle (30, 31) for adjusting the frequency or maximum deflection of the lifting movement or lifting /pendulum movement (12, 13).

10. Tool assembly (1) according to any one of claims 1 - 9, characterized in that the oscillation means (11) is provided with an eccentric cam rotatably mounted in the tool assembly (1), in which the tool (2) is eccentrically mounted, whereby the tool (2) is fully floating in the tool assembly (1) at a distance from the eccentric mounting.

11. Tool assembly (1) according to any one of claims 1 -10, characterized in that at least one force and torque sensor (33) is arranged between the tool (2) and a guidance means of the tool assembly (1) for guiding the tool (2) along the contour of the workpiece.

12. Tool assembly (1) according to claim 11, characterized in that the output signals of the force / torque sensor (33) for calculating triggering signals for the guidance means of the tool assembly (1) are controlled by a control system of a robot.