Numerical control device

Abstract

The numerical control device of a machine tool comprises: a storage unit storing a machining program for drilling a hole (4a) in a workpiece (4) by relative movement of a tool and the workpiece in a depth direction; and a control unit controlling the relative movement of the tool and the workpiece (4) according to the machining program and causing the tool to move relative to the workpiece (4) from a reset point (R) to a hole bottom point (Z) along the depth direction, the reset point (R) being a position retreated in the depth direction from a workpiece surface (4b) where drilling of the hole is started by the tool, the machining program including an instruction for a workpiece height point (W), the workpiece height point (W) being a position of the workpiece surface (4b) in the depth direction, and the control unit causing the tool to move relative to the workpiece (4) from the reset point (R) to the workpiece height point (W) along the depth direction.

Description

Technical Field

[0001] The invention relates to a numerical control device. Background Art

[0002] Conventionally, a method of repeating a fixed cycle is used in drilling a workpiece (for example, see Patent Documents 1 and 2). In Patent Documents 1 and 2, in order to achieve high-speed drilling, the path and speed of the relative movement of the tool with respect to the workpiece are optimized, and non-cutting time is shortened.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 09-120310

[0006] Patent Document 2: Japanese Patent Application Publication No. 2017-004300 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In Patent Document 1, the tool is moved to the machining start point above the workpiece surface by rapid feed, and is moved from the machining start point to the hole bottom by cutting feed, but there is room for further optimization of the tool movement in order to further shorten the non-cutting time.

[0009] Solutions for solving problems

[0010] One embodiment of the present invention is a numerical control device, which is a numerical control device for a machine tool, the numerical control device comprising: a storage unit, which stores a machining program, the machining program being used to drill a hole in the workpiece by relative movement of the tool and the workpiece in the depth direction along the long axis of the tool; and a control unit, which controls the relative movement of the tool and the workpiece according to the machining program, and moves the tool relative to the workpiece from a reset point along the depth direction to a hole bottom point, the reset point being a position retreated in the depth direction from the workpiece surface where the hole is started to be drilled using the tool, the machining program including an instruction for a workpiece height point, the workpiece height point being the position of the workpiece surface in the depth direction, the control unit moving the tool relative to the workpiece from the reset point along the depth direction to the workpiece height point at a relative speed faster than a cutting feed speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of a machine tool according to an embodiment.

[0012] Figure 2This is a diagram showing an example of a fixed cycle program for drilling holes.

[0013] Figure 3 This is a diagram for explaining an example of drilling processing using a fixed cycle for drilling.

[0014] Figure 4 This is a diagram showing another example of a fixed cycle program for drilling a hole. DETAILED DESCRIPTION

[0015] Hereinafter, a numerical control device according to an embodiment will be described with reference to the drawings.

[0016] like Figure 1 As shown, the numerical control device 1 is a numerical control device of a machine tool 10 that processes a workpiece 4 using a tool 2 .

[0017] The machine tool 10 includes: a spindle 3 that holds a tool 2; a worktable 5 that holds a workpiece 4; a spindle motor 6 that rotates the spindle 3; a Z-axis feed motor 7 that moves the spindle 3 in the Z direction relative to the worktable 5; an X-axis feed motor 8 and a Y-axis feed motor 9 that move the worktable 5 in the X direction and the Y direction relative to the spindle 3, respectively; and a numerical control device 1 that controls motors 6, 7, 8, and 9.

[0018] The Z direction is a direction along the long axis of the tool 2 held on the spindle 3. The X direction and the Y direction are directions perpendicular to the long axis of the tool 2 held on the spindle 3, and are perpendicular to each other. Figure 1 In the machine tool 10 , the Z direction is a vertical direction, and the X direction and the Y direction are horizontal directions.

[0019] The spindle 3 is arranged in the vertical direction and supported by a supporting mechanism (not shown) so as to be movable in the vertical direction. The tool 2 is coaxially held at the lower end of the spindle 3 and rotates and moves integrally with the spindle 3. The tool 2 is a drill for drilling a hole 4a in the workpiece 4 in the depth direction (Z direction). The tool 2 may also be other types of tools for machining the workpiece 4 in the depth direction, such as a milling cutter or an end mill.

[0020] The table 5 is horizontally disposed below the spindle 3. The workpiece 4 placed on the upper surface of the table 5 is fixed to the table 5 by a jig (not shown).

[0021] The spindle motor 6 is a spindle motor connected to the upper end of the spindle 3 , and rotates the spindle 3 around the long axis of the spindle 3 .

[0022] The feed motors 7, 8, and 9 are servomotors, respectively.

[0023] The numerical control device 1 includes a storage unit 11 and a control unit 12 .

[0024] The storage unit 11 includes, for example, a RAM, a ROM, or other storage devices, and stores a processing program 11a (see FIG. 1 ) for drilling a hole in the workpiece 4 by relative movement of the tool 2 and the workpiece 4. Figure 2 . ).

[0025] The control unit 12 includes a processor such as a central processing unit and controls the feed motors 7 , 8 , and 9 according to the machining program 11 a to control the relative movement of the spindle 3 and the table 5 , thereby controlling the relative movement of the tool 2 and the workpiece 4 .

[0026] like Figure 2 As shown, the machining program 11a includes a fixed cycle program 11b for drilling. Figure 3 As shown, the fixed cycle program 11b is a program that causes the machine tool 10 to execute multiple fixed cycles, and the fixed cycles include positioning actions, hole-making actions, and drawing actions. Figure 3 In FIG. 4 , the dotted and solid arrows represent the path of relative movement of the tool 2 relative to the workpiece 4. Figure 3 In the diagram, the horizontal direction is the XY direction, and the vertical direction is the Z direction.

[0027] The machining program 11a includes instructions for specifying the W point (workpiece height point), the R point (reset point), and the Z point (hole bottom point). The W point is the position of the workpiece surface 4b in the Z direction. The workpiece surface 4b is the surface of the workpiece 4 where the tool 2 starts to drill (cut) the workpiece 4, and in this embodiment, it is the upper surface of the workpiece 4. The R point is a position in the Z direction that is retreated from the workpiece surface 4b in the Z direction, for example, a position separated from the workpiece surface 4b by 1mm to 5mm. The Z point is the position of the bottom of the hole 4a in the Z direction, and is located on the opposite side of the R point relative to the workpiece surface 4b.

[0028] The positioning operation is an operation in which the workpiece 4 is moved relative to the tool 2 in the XY directions by moving the table 5 in the XY directions, and the hole opening position of the workpiece 4 is positioned relative to the tool 2 in the XY directions. Paths a and b are paths of the tool 2 in the positioning operation.

[0029] The drilling operation is an operation in which the tip 2a of the tool 2 moves from point R to point Z along the Z direction by lowering the spindle 3, and a hole is drilled at the drilling position of the workpiece 4. Paths b and c are paths of the tool 2 during the drilling operation.

[0030] The pulling operation is an operation in which the tip 2a of the tool 2 is moved from point Z to point R in the Z direction by the rise of the spindle 3, and the tool 2 is pulled out from the hole 4a. Paths d and e are paths of the tool 2 during the positioning operation.

[0031] Figure 2 An example of a fixed cycle program 11b in which a fixed cycle is repeated three times is shown.

[0032] "G81" is a code for commanding a fixed cycle for drilling, "G99" is a code for commanding R point reset, and "G80" is a code for commanding the cancellation of a fixed cycle. "X0 Y0" is a positioning command for the X and Y directions of the drilling position, "Z-10." is a command for the Z point, "R5." is a command for the R point, "W1." is a command for the W point, and "F1000" is a command for the cutting feed rate. That is, the R point is set to Z = 5mm, the Z point is set to Z = -10mm, and the W point is set to Z = 1mm. In the second and third rows, the commands Y, Z, R, W, and F, which have the same command values ​​as the first row, are omitted.

[0033] The control unit 12 controls the movement of the spindle 3 and the tool 2 in the Z direction by controlling the feed motor 7 , and controls the movement of the table 5 and the workpiece 4 in the XY directions by controlling the feed motors 8 and 9 .

[0034] The control unit 12 controls the feed motors 7 , 8 , and 9 while rotating the main spindle 3 and the tool 2 using the main spindle motor 6 , thereby causing the machine tool 10 to perform positioning operations, drilling operations, and pulling operations.

[0035] Here, the control unit 12 starts the drilling operation before the positioning operation is completed, so that the movement of the workpiece 4 in the XY direction of the positioning operation overlaps in time with the movement of the tool 2 in the Z direction of the drilling operation. As a result, the front end 2a of the tool 2 moves along the first curved path b from point R to point W.

[0036] In addition, the control unit 12 starts the positioning operation of the next fixed cycle before the end of the pulling operation, so that the rise of the tool 2 in the Z direction of the pulling operation and the movement of the workpiece 4 in the XY direction of the positioning operation overlap in time. As a result, the front end 2a of the tool 2 moves along the second curved path e from point W to point R.

[0037] The control unit 12 moves the workpiece 4 at a fast feed rate in the positioning operation and moves the tool 2 at a fast feed rate in the drawing operation. In addition, the control unit 12 moves the tool 2 from point R to point W at a fast feed rate in the drilling operation, and then moves the tool 2 from point W to point Z at a cutting feed rate.

[0038] The rapid feed rate is the maximum speed of each feed motor 7, 8, 9. The cutting feed rate is a speed that is slower than the rapid feed rate and is suitable for drilling a hole in the workpiece 4 using the tool 2.

[0039] exist Figure 3In FIG. 1 , the paths a, b, d, and e of the tool 2 moving at a rapid feed rate relative to the workpiece 4 are indicated by dotted lines, and the path c of the tool 2 moving at a cutting feed rate relative to the workpiece 4 is indicated by a solid line. Figure 3 In the figure, the position of the straight path d is offset from the position of the straight path c in the XY direction, but in fact the two straight paths c and d overlap each other.

[0040] Next, a method for controlling the machine tool 10 using the numerical control device 1 will be described.

[0041] When the fixed cycle program 11 b is started, the control unit 12 causes the machine tool 10 to execute the first fixed cycle. That is, the control unit 12 controls the feed motors 8 and 9 to cause the table 5 to start positioning and position the first hole opening position of the workpiece 4 relative to the tool 2 .

[0042] Then, the control unit 12 controls the feed motor 7 to start the main spindle 3 to perform the hole-drilling operation, and drills a hole at the first hole-drilling position using the tool 2. Here, the control unit 12 starts the hole-drilling operation before the positioning operation is completed, so that the front end 2a of the tool 2 moves along the curved path b. During the hole-drilling operation, the control unit 12 moves the tool 2 from point R to point W at a rapid feed rate, and moves the tool 2 from point W to point Z at a cutting feed rate.

[0043] After the hole drilling operation is completed, the control unit 12 controls the feed motor 7 to start the pulling operation of the spindle 3 to pull the tool 2 from the hole 4 a .

[0044] Then, the control unit 12 causes the machine tool 10 to execute the second fixed cycle. That is, the control unit 12 causes the table 5 to start the positioning operation and positions the second hole opening position of the workpiece 4 relative to the tool 2. Here, the control unit 12 causes the front end 2a of the tool 2 to move along the curved path e by starting the positioning operation of the second fixed cycle before the drawing operation of the first fixed cycle is completed.

[0045] Thereafter, the control unit 12 performs the drilling operation and the drawing operation of the second fixed cycle in the same manner as the first fixed cycle, and then performs the third fixed cycle.

[0046] Thus, according to the present embodiment, while the tip 2a of the tool 2 moves from the R point toward the W point in the Z direction, the movement of the tool 2 in the Z direction overlaps with the movement of the workpiece 4 in the XY direction in time, and the tool 2 moves along the curved path b. In addition, while the tip 2a of the tool 2 moves from the W point toward the R point in the Z direction, the movement of the tool 2 in the Z direction overlaps with the movement of the workpiece 4 in the XY direction in time, and the tool 2 moves along the curved path e. Thus, compared with the case where the hole opening action is started after the positioning action is completely completed, and the next positioning action is started after the pulling action is completely completed, the non-cutting time during which the tool 2 does not cut the workpiece 4 is shortened.

[0047] In addition, the fixed cycle program 11b is different from the conventional fixed cycle program for drilling in that it includes the command of the W point. The conventional numerical control device that controls the movement of the tool 2 according to the conventional fixed cycle program moves the tip 2a of the tool 2 from the R point to the Z point at the cutting feed speed. According to the present embodiment, by adding the command of the W point, the speed from the R point to the W point can be controlled to a speed other than the cutting feed speed, and the tool 2 can be moved from the R point to the W point at the rapid feed speed. Thus, the non-cutting time can be further shortened.

[0048] In this embodiment, the tool 2 is set to move from point R to point W at a rapid feed rate, but the moving speed of the tool 2 in the Z direction from point R to point W may be any speed that is faster than the cutting feed rate and slower than the rapid feed rate. In addition, the moving speed of the tool 2 from point R to point W may be changed between the cutting feed rate and the rapid feed rate.

[0049] For example, Figure 4 As shown, you can also specify the cutting feed rate F C And the rapid feed rate F R The speed ratio argument L is added to the fixed cycle program 11b. L is a value in the range of 0% to 100%. The moving speed F of the tool 2 is defined by the following formula.

[0050] F=F C ×(1-(L / 100))+F R ×L / 100

[0051] By setting the value of L, the operator can designate the speed F to any speed between the cutting feed speed and the rapid feed speed.

[0052] In this embodiment, the tool 2 is set to move from point R to point W at a rapid feed speed, but the movement speed of the tool 2 in the Z direction from point R to point W can also be changed in stages from rapid feed to cutting feed according to the position of the front end 2a of the tool 2.

[0053] For example, if the position of the front end 2a is set to Z n , then according to the cutting feed speed F C And the rapid feed rate F R The moving speed F of the tool 2 in the Z direction is defined by the following formula.

[0054] F=(F C ×|RZ n |+F R ×|Z n -W|) / |RW|

[0055] By changing the position of the front end 2a, the speed F can be changed in stages from the rapid feed speed to the cutting feed speed.

[0056] In this embodiment, the tool 2 is set to move from point R to point W at a rapid feed speed, but the moving speed of the tool 2 in the Z direction from point R to point W can also be changed from rapid feed to cutting feed at any position between point R and point W.

[0057] For example, according to the responsiveness of the mechanical control, the rapid feed speed may be changed to the cutting feed speed at an intermediate position between the points R and W. Thus, in a machine tool with low responsiveness of the mechanical control, when the positioning of the front end 2a is inaccurate at the time of reaching the point W, by changing the moving speed in the Z direction from the rapid feed speed to the cutting feed at a position higher than the point W, the arrival time can be changed, and the non-cutting time can be shortened and accurate positioning can be achieved.

[0058] In the present embodiment, the control unit 12 is set to control the feed motors 7, 8, and 9 so that the tool 2 moves along the curved paths b and e between the R point and the W point, but instead, the feed motors 7, 8, and 9 may be controlled so that the tool 2 moves only along a straight path. That is, the control unit 12 may start the hole opening action after the positioning action is completed, and may start the positioning action of the next fixed cycle after the drawing action is completed.

[0059] Even in such control, the non-cutting time can be shortened by setting the moving speed of the tool 2 in the Z direction from the R point to the W point to be faster than the cutting feed speed.

[0060] In the present embodiment, it is set that the fixed cycle program 11b includes the W point, but the W point may be defined by a parameter in a data table format stored in a memory. In addition, the W point may be a predetermined fixed value.

[0061] For example, the W point may be stored in advance as 1.0 mm in the storage unit 11 of the numerical controller 1 , and the W point may be called when the fixed cycle program 11 b is instructed.

[0062] In addition, the W point may be a fixed value set at a position closer to the workpiece 4 by -4.0 mm than the R point when the fixed cycle program 11b is commanded. In the drilling process, in order to shorten the non-cutting time, the R point is often set at a position separated by 0.5 mm to 1.0 mm from the upper surface of the workpiece 4. Therefore, by setting the W point to a position closer to the workpiece 4 by -4.0 mm than the R point, the non-cutting time can be shortened without the command of the W point.

[0063] In this embodiment, each hole 4a is formed by non-stop machining, but each hole 4a may be formed by stepping machining instead. Stepping machining is a method of making the tool 2 reciprocate multiple times in the Z direction, dividing the distance from point W to point Z into multiple times and cutting a predetermined amount each time.

[0064] In the conventional stepping process, the tool 2 returns to the R point after each cutting of the workpiece 4. In the present embodiment, the tool 2 may be returned to the W point or any height between the R point and the W point instead of the R point, and the next descent of the tool 2 may be started from the W point or any height between the R point and the W point. Thus, the time required for machining one hole 4a can be shortened.

[0065] In this embodiment, the drilling process using a fixed cycle is described, but the present invention can also be applied to drilling processes that do not use a fixed cycle. That is, a W point instruction can be added to any drilling process program, and during the drilling operation in any drilling process, the tool and the workpiece can be relatively moved from the R point to the W point in the depth direction at a speed faster than the cutting feed speed.

[0066] In this embodiment, it is assumed that the tool 2 can move in the Z direction and the workpiece 4 can move in the XY direction, but the relative movement of the tool 2 and the workpiece 4 can be achieved by moving any one or both of the tool 2 and the workpiece 4. For example, the spindle 3 can move in the XY direction and the table 5 can move in the Z direction. Alternatively, one of the spindle 3 and the table 5 can move in the three directions of X, Y, and Z.

[0067] In addition, in the present embodiment, the moving direction of the tool 2 is set to be the vertical direction, and the moving direction of the workpiece 4 is set to be the horizontal direction, but the moving directions of the tool 2 and the workpiece 4 can be appropriately changed according to the specifications of the machine tool. For example, for a machine tool with a horizontally arranged spindle 3, the moving direction of the tool 2 can be the horizontal direction, and the moving direction of the workpiece 4 can be the vertical direction.

[0068] Description of reference numerals:

[0069] 1: Numerical control device

[0070] 2: Tools

[0071] 4: Artifacts

[0072] 4a: Hole

[0073] 4b: Workpiece surface

[0074] 10: Machine tools

[0075] 11: Storage

[0076] 11a: Processing procedures

[0077] 11b: Fixed cycle program

[0078] 12: Control Department

Claims

1. A numerical control device, which is a numerical control device for a machine tool, characterized in that: have: a storage unit storing a processing program for drilling a hole in the workpiece by relative movement of a tool and the workpiece in a depth direction along a long axis of the tool; as well as a control unit that controls the relative movement of the tool and the workpiece according to the machining program and moves the tool relative to the workpiece from a reset point to a hole bottom point along the depth direction, The reset point is a position where the workpiece surface is retreated in the depth direction from where the hole is opened by the tool. The machining program includes instructions for a workpiece height point, where the workpiece height point is the position of the workpiece surface in the depth direction. The control unit moves the tool relative to the workpiece from the reset point along the depth direction to an intermediate position between the reset point and the workpiece height point at a rapid feed speed faster than a cutting feed speed, and changing the relative speed of the tool with respect to the workpiece in the depth direction from the rapid feed speed to the cutting feed speed at the intermediate position, The intermediate position is determined based on the responsiveness of a mechanical control of the machine tool.

2. The numerical control device according to claim 1, characterized in that: The workpiece height point is a numerical value stored in the numerical control device.

3. The numerical control device according to claim 1 or 2, characterized in that: The machining program causes the machine tool to execute multiple fixed cycles, wherein the fixed cycles include positioning actions, hole opening actions, and drawing actions. The positioning action is an action of positioning the hole opening position of the workpiece relative to the tool by relative movement of the tool and the workpiece in a direction intersecting the depth direction. The hole-opening action is an action of opening a hole at the hole-opening position by moving the tool from the reset point to the hole bottom point in the depth direction, The pulling action is an action of pulling the tool out of the hole by moving the tool from the hole bottom point to the reset point in the depth direction. The control unit is used to: The hole-opening action is started before the positioning action is completed, so that the tool moves relatively along a first curved path from the reset point to the workpiece height point. By starting the positioning action of the next fixed cycle before the drawing action is finished, the tool is relatively moved along the second curved path from the workpiece height point to the reset point.

4. The numerical control device according to claim 1 or 2, characterized in that: In stepping processing in which the tool is reciprocated multiple times in the depth direction and a hole is opened by a predetermined amount each time to the hole bottom point, the control unit retreats the tool to the workpiece height point or a height between the reset point and the workpiece height point.

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