Method for controlling a device system having power tool and a motor-driven advancing mechanism

Abstract

A method for controlling a device system (10) having a saw blade (14) that is attached to a saw arm (15) and that can be moved along an advancing direction (26) by a motor-driven advancing mechanism (13), whereby there is an infeed motion of the saw arm (15) with the saw blade (14) into the workpiece (18) and, during the infeed motion of the saw arm (15) into the workpiece (18), a control unit (27) calculates an arc length (φ) of the saw blade (14) that is engaged with the workpiece (18), and the calculated arc length (φ) is compared to a pre-set, critical arc length (φ.sub.crit) of the saw blade (14).

Claims

1. A method for controlling a device system having a saw blade attached to a saw arm, the saw blade movable along an advancing direction by a motor-driven advancer, the method comprising: calculating, via a controller during an infeed motion of the saw arm with the saw blade into the workpiece, an arc length of the saw blade engaged with the workpiece; and comparing the calculated arc length to a pre-set, critical arc length of the saw blade.

2. The method as recited in claim 1 wherein the infeed motion of the saw arm is interrupted and the saw blade undergoes an advancing movement in a forward direction along the advancing direction when the calculated arc length matches the critical arc length of the saw blade.

3. The method as recited in claim 2 wherein the controller calculates a movement of the saw blade in the forward direction during the advancing movement of the saw blade, and the calculated movement is compared to a pre-set, first movement.

4. The method as recited in claim 3 wherein the advancing movement of the saw blade is interrupted and further comprising providing an additional infeed motion of the saw arm into the workpiece when the calculated movement of the saw blade matches the first movement.

5. The method as recited in claim 4 wherein, during the further infeed motion of the saw arm, the controller calculates a further arc length of the saw blade engaged with the workpiece, and the further calculated arc length of the saw blade is compared to a further critical arc length.

6. The method as recited in claim 5 wherein the additional infeed motion of the saw arm is interrupted and further comprising providing a further advancing movement of the saw blade along the advancing direction in a backward direction opposite from the forward direction when the further calculated arc length matches the further critical arc length of the saw blade.

7. The method as recited in claim 6 wherein, during the further advancing movement of the saw blade, the control unit calculates a further movement of the saw blade in the backward direction, and the calculated further movement is compared to a pre-set, second movement.

8. The method as recited in claim 7 wherein the further advancing movement of the saw blade is interrupted when the further calculated movement of the saw blade matches the second movement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following is shown:

(2) FIG. 1: a rail-guided device system consisting of a guide rail, a saw head that is arranged so as to be movable on the guide rail, and a motor-driven advancing mechanism to move the saw head along the guide rail; and

(3) FIGS. 2A-E: the saw head of FIG. 1, with a saw blade that is attached to a swiveling arm, in five different positions during the plunging of the saw blade into a workpiece that is to be processed.

DETAILED DESCRIPTION

(4) FIG. 1 is a schematic view of a rail-guided device system 10, consisting of a guide rail 11, a power tool 12 that is arranged so as to be movable on the guide rail 11, and a motor-driven advancing mechanism 13 to move the power tool 12 along the guide rail 11.

(5) The power tool is configured as a saw head 12 and it comprises a saw blade 14 that is attached to a saw arm 15 and that is driven around a rotational axis 16. The saw arm 15 is configured so that it can be swiveled around the swivel axis 17. The cutting depth of the saw blade 14 is varied by a swiveling movement of the saw arm 15 around the swivel axis 17. The swivel angle of the saw arm 15, together with the diameter of the saw blade 14, determines how deep the saw blade 14 plunges into the workpiece 18 that is to be processed. As an alternative to the swiveling movement of the saw arm 15 around the swivel axis 17, the saw arm 15 can be adjusted, for instance, by means of a linear drive or another such drive unit. The plunging of the saw blade 14 into the workpiece 18 is referred to as the infeed motion of the saw arm 15, irrespective of the structural design of the drive unit. In order to protect the operator, the saw blade 14 can be surrounded by a blade guard that is attached to the saw arm 15 by means of a blade guard holder.

(6) The saw blade 14 is rotated around the rotational axis 16 by a drive motor 21, while the saw arm 15 is swiveled around the swivel axis 17 by a swivel motor 22. The drive motor 21 and the swivel motor 22 are arranged in a device housing 23 of the saw head 12. The motor-driven advancing mechanism 13 comprises a guide carriage 24 and an advancing motor 25 that is arranged in the device housing 23. The saw head 12 is installed on the guide carriage 24 and configured so as to be movable by the advancing motor 25 along the guide rail 11 in an advancing direction 26. The device housing 23 accommodates not only the motors 21, 22, 25, but also a first control unit 27 to control the saw head 12 and the motor-driven advancing mechanism 13. A method according to the invention for controlling the device system 10 when the saw blade 14 plunges into the workpiece 18 that is to be processed is stored in the first control unit 27.

(7) The saw blades 14 used for the saw head 12 are made up of two parts, namely, a base body and several cutting segments, whereby the cutting segments are arranged along the circumference of the base body. The cutting segments are made of a matrix material in which diamond particles are embedded. A minimum surface pressure is required in order to expose the diamond particles during the processing. If the value falls below the minimum surface pressure, the diamond particles are not exposed during the processing with the saw blade 14 and the risk exists that the cutting segments will become polished, which reduces the working speed of the saw blade 14 as well as the service life. The minimum surface pressure of the cutting segments corresponds to a critical arc length φ.sub.crit of the saw blade 14. For this reason, the arc length of the saw blade 14 that is engaged with the workpiece 18 should not exceed the critical arc length φ.sub.crit. The value of the critical arc length φ.sub.crit of a saw blade 14 depends on several parameters, among others, the specification of the saw blade 14, the material of the workpiece 18 as well as the output and the torque of the drive motor 21.

(8) The device system 10 is operated by means of a control unit 28 which, in the embodiment shown in FIG. 1, is configured as a remote control unit. The remote control unit 28 comprises a device housing 29, a second control unit 31 accommodated in the device housing 29 as well as an operating means 32 and a display means 33 that are arranged on the top 34 of the device housing 29. The second control unit 31 is connected to the first control unit 27 via a communication connection 35. The communication connection 35 is configured as a hard-wired connection or else as a wireless communication connection, for example, in the form of an infrared, Bluetooth, WLAN or Wi-Fi connection. Aside from the listed wireless connection technologies, all familiar and future wireless connection technologies for data transmission are suitable.

(9) The device system 10 has a sensor system 36 with several sensor elements in order to monitor the device system 10 and the work process. A first sensor element 37 is configured as a swivel-angle sensor, while a second sensor element 38 is configured as a position sensor. The swivel-angle sensor 37 measures the momentary swivel angle of the saw arm 15. The swivel angle of the saw arm 15, together with the diameter of the saw blade 14, determines how deep the saw blade 14 plunges into the workpiece 18. The position sensor 38 measures the momentary position of the saw head 12 on the guide rail 11. The measured quantities are transmitted to the first control unit 27 by the swivel-angle sensor 37 and by the position sensor 38.

(10) FIGS. 2A-E show the saw head 12 and the saw arm 15 with the mounted saw blade 14 of the device system 10, in five different positions when the saw blade 14 plunges into a workpiece 18 that is to be processed. The plunging takes place automatically by means of the method according to the invention for controlling a device system when the saw blade plunges into the workpiece.

(11) FIG. 2A shows the saw head 12 and the saw arm 15 with the mounted saw blade 14 in a basic position. In the basic position, the saw blade 14 is located above the workpiece 18. From the basic position, the saw blade 14 is moved into the workpiece 18 by a swiveling movement of the saw arm 15 around the swivel axis 17. During the swiveling movement of the saw arm 15, the saw blade 14 is driven around the rotational axis 16 by the drive motor 21. The saw blade 14 creates a first cut wedge 41 in the workpiece 18 (FIG. 2B). During the swiveling movement of the saw arm 15, the first control unit 27 calculates an arc length φ of the saw blade 14 that is engaged with the workpiece 18 and compares it to the critical arc length φ.sub.crit. The arc length of the saw blade 14 that is engaged with the workpiece 18 can be calculated on the basis of the diameter of the saw blade 14, on the basis of the swiveling angle of the saw arm 15 and on the basis of the position of the saw head 12. The swiveling angle of the saw arm 15 is measured by the swiveling angle sensor 37, while the position of the saw head 12 is measured by the position sensor 38. As soon as the arc length φ of the saw blade 14 matches the critical arc length φ.sub.crit, the swiveling movement of the saw arm 15 is interrupted. FIG. 2B shows the saw arm 15 with the saw blade 14 after the first swiveling movement of the saw arm 15. The saw arm 15 is slanted at a first swiveling angle α.sub.1.

(12) The saw head 12 with the slanted saw arm 15 is moved by the motor-driven advancing mechanism 13 in a forward direction 42 along the advancing direction 26. During the advancing movement, the arc length φ of the saw blade 14 that is engaged with the workpiece 18 decreases and falls below the critical arc length φ.sub.crit. During the advancing movement of the saw head 12 in the forward direction 42, the position of the saw head 12 is monitored by the position sensor 38. The position sensor 38 transmits the position of the saw head 12 to the first control unit 27, which then calculates a movement Δ. As soon as the saw head 12 has been moved by a pre-set, first movement Δ.sub.1 in the forward direction 42, for instance, 1/10 to 3/20 of the diameter of the saw blade 14, the advancing movement of the saw head 12 in the forward direction 42 is interrupted. FIG. 2C shows the saw head 12 and the saw arm 15 with the saw blade 14 after the first advancing movement of the saw head 12. The saw arm 15 continues to be slanted at the first swiveling angle α.sub.1.

(13) When the saw head 12 is stationary, the saw blade 14 is moved out of the first swiveling angle α.sub.1 around the swivel axis 17 and further into the workpiece 18 by a swiveling movement of the saw arm 15 (FIG. 2D). During the swiveling movement of the saw arm 15, the arc length φ of the saw blade 14 that is engaged with the workpiece 18 is calculated and compared to the critical arc length φ.sub.crit. As soon as the arc length φ of the saw blade 14 matches the critical arc length φ.sub.crit, the swiveling movement of the saw arm 15 is interrupted. FIG. 2D shows the saw head 12 and the saw arm 15 with the saw blade 14 after the second swiveling movement of the saw arm 15, which is slanted at a second swiveling angle α.sub.2.

(14) After the second swiveling movement of the saw arm 15, the saw blade 14 is moved by the motor-driven advancing mechanism 13 in a backward direction 43 opposite from the forward direction 42. During the advancing movement, the arc length φ of the saw blade 14 that is engaged with the workpiece 18 decreases and falls below the critical arc length φ.sub.crit of the saw blade 14. During the advancing movement of the saw head 12 in the backward direction 43, the position of the saw head 12 is monitored by the position sensor 38. As soon as the saw head 12 has been moved by a pre-set, second movement Δ.sub.2 in the backward direction 43, for instance, 1/10 to 3/20 of the diameter of the saw blade 14, the advancing movement of the saw head 12 in the backward direction 43 is interrupted. FIG. 2E shows the saw head 12 and the saw arm 15 with the saw blade 14 after the second advancing movement of the saw head 12. The saw arm 15 continues to be slanted at the second swiveling angle α.sub.2.

(15) The first movement Δ.sub.1 in the forward direction 42 and the second movement Δ.sub.2 in the backward direction 43 are pre-set values that have been stored in the first control unit 27. The values Δ.sub.1, Δ.sub.2 are selected in such a way that the saw blade 14 eases off the workpiece after the infeed motion and the arc length φ of the saw blade 14 that is engaged with the workpiece 18 falls below the critical arc length φ.sub.crit. As a rule, the values of the first and second movements Δ.sub.1, Δ.sub.2 match and differ only in terms of the movement directions 42, 43. This configuration causes the saw blade 14 to be once again situated in the starting position, after the second advancing movement in the advancing direction 26. The swiveling movement of the saw arm 15 around the swivel axis 17 and the advancing movement of the saw head 12 along the advancing direction 26 are carried out alternatingly until the plunging of the saw blade 14 is ended and the saw blade 14 has reached the desired cutting depth in the workpiece 18.