Cycle 1021 CYLINDER, SLOW-STROKE GRINDING (#156 / #4-04-1)

ISO programming

G1021

Application

 
Machine

Refer to your machine manual!

This function must be enabled and adapted by the machine manufacturer.

Cycle 1021 CYLINDER, SLOW-STROKE GRINDING allows you to grind circular pockets or circular studs. The height of the cylinder can be considerably greater than the width of the grinding wheel. Through a reciprocating stroke, the control can machine the complete height of the cylinder. The control executes multiple circular paths during the reciprocating stroke. In this process, the reciprocating stroke and the circular paths overlap to form a helix. This process is equivalent to grinding with a slow stroke.

The lateral infeed cuts occur at the reversal points of the reciprocating stroke along the semi-circle. You can program the feed rate of the reciprocating stroke as the pitch of the helical path relative to the width of the grinding wheel.

You can also completely machine cylinders without overshoot, such as blind holes. This is done by programming idle runs at the reversal points of the reciprocating stroke.

Cycle run

  1. The control positions the grinding tool above the cylinder based on POCKET POSITION Q367. The control then moves the tool to the CLEARANCE HEIGHT Q260 at rapid traverse.
  2. The grinding tool uses F PRE-POSITIONING Q253 for moving to the SET-UP CLEARANCE Q200
  3. The grinding tool traverses to the starting point in the tool axis. The starting point depends on the MACHINING DIRECTION Q1031, upper or lower reversal point of the reciprocating stroke.
  4. The cycle starts the reciprocating stroke. At the GRINDING FEED RATE Q207, the control moves the grinding tool to the contour.
  5. Feed rate for the reciprocating stroke

  6. The control delays the reciprocating stroke in the starting position.
  7. Depending on Q1021 ONE-SIDED INFEED, the control infeeds the grinding tool in a semi-circle around the lateral infeed Q534 1.
  8. As needed, the control executes the defined idle runs 2 Q211 or Q210.
  9. Overshoot and idle runs to the reversal points of the reciprocating stroke

  10. The cycle continues the reciprocating movement. The grinding tool follows multiple circular paths. The reciprocating stroke overlays the circular paths in the direction of the tool axis to form a helix. You can influence the pitch of the helical path by the factor Q1032.
  11. The circular paths 3 repeat themselves until the second reversal point of the reciprocating stroke is reached.
  12. The control repeats steps 4 to 7 until the diameter of the finished part Q223 or the oversize Q14 is reached.
  13. After the last lateral infeed run, the grinding wheel moves the number of programmed idle strokes Q1020 if applicable.
  14. The control stops the reciprocating stroke. The grinding tool leaves the cylinder on a semi-circular path to the safety clearance Q200.
  15. At F PRE-POSITIONING Q253, the grinding tool moves to the SET-UP CLEARANCE Q200 and then at rapid traverse to the CLEARANCE HEIGHT Q260.
 
Tip
  • In order for the grinding tool to completely machine the cylinder at the reversal points of the reciprocating stroke, you must define sufficient overshoot or idle runs.
  • The length of the reciprocating stroke arises from the DEPTH Q201, the SURFACE OFFSET Q1030 and the wheel width B.
  • The distance of the starting point in the working plane from the FINISHED PART DIA. Q223 including the OVERSIZE AT START Q368 is equal to the amount of the tool radius plus the SET-UP CLEARANCE Q200.

Overshoot and idle runs to the reversal points of the reciprocating stroke

Path of the overshoot

Top

Bottom

This distance is defined in the parameter Q1030 SURFACE OFFSET.

You must add this distance to the machining depth and then define it in Q201 DEPTH.

If no overshoot is possible, such as with a pocket, program multiple idle runs at the reversal points of the reciprocating stroke (Q210, Q211). Select this number such that, after infeeding (half of a circular path), at least one circular path is traveled on the infed diameter. The number of idle runs is always based on a set feed-rate override of 100%.

 
Tip
  • HEIDENHAIN recommends moving with a feed-rate override of 100% or more. A feed-rate override of less than 100% no longer ensures that the cylinder will be completely machined at the reversal points.
  • For the definition of idle runs, HEIDENHAIN recommends defining at least a value of 1.5.

Feed rate for the reciprocating stroke

You can define the pitch per helical path (=360°) with the factor Q1032. Through this definition, the feed rate in mm or in inches/helical path (= 360°) can be derived for the reciprocating stroke.

The proportion of the GRINDING FEED RATE Q207 to the feed rate of the reciprocating stroke plays a major role. If you deviate from a feed rate override of 100%, then ensure that the length of the reciprocating stroke during a circular path is less than the width of the grinding wheel.

 
Tip

HEIDENHAIN recommends selecting a factor of at most 0.5.

Notes

 
Machine

The overrides for the reciprocation movements can be changed by the machine manufacturer.

  • This cycle can be executed only in the FUNCTION MODE MILL machining mode.
  • The last lateral infeed may be smaller depending on the input.
  • The control does not depict the reciprocating movement in the simulation. The graphic simulation in the Program Run operating mode shows the reciprocation movement.
  • You can also execute this cycle with a milling cutter. In the case of a milling cutter, the tooth length LCUTS equals the width of the grinding wheel.
  • Please note that the cycle takes M109 into account. The GRINDING FEED RATE Q207 in the status display during program run in the case of a pocket is therefore smaller than in the case of a stud. The control shows the feed rate of the center point path of the grinding tool, including the reciprocating stroke.
  • Adapting the feed rate for circular paths with M109

Notes on programming

  • The control assumes that the bottom of the cylinder has a floor. For this reason, you can define an overshoot in Q1030 only at the surface. If you machine a through hole, for example, then you must take into account the lower overshoot in DEPTH Q201.
  • Overshoot and idle runs to the reversal points of the reciprocating stroke

  • If the grinding wheel is wider than DEPTH Q201 and the SURFACE OFFSET Q1030, then the control issues a No swing stroke error message. In this case, the resulting reciprocating stroke would be equal to 0.

Cycle parameters

Help graphic

Parameter

Q650 Type of figure?

Geometry of the figure:

0: Pocket

1: Island

Input: 0, 1

Q223 Finished part diameter?

Diameter of the fully machined cylinder

Input: 0...99999.9999

Q368 Side oversize before machining?

Lateral oversize that is present prior to the grinding operation. This value must be greater than Q14. This value has an incremental effect.

Input: –0.9999...+99.9999

Q14 Finishing allowance for side?

Lateral oversize that is to remain after machining. This allowance must be less than Q368. This value has an incremental effect.

Input: –99999.9999...+99999.9999

Q367 Position of pocket (0/1/2/3/4)?

Position of the figure relative to the position of the tool during the cycle call:

0: Tool pos. = Center of figure

1: Tool pos. = Quadrant transition at 90°

2: Tool pos. = Quadrant transition at 0°

3: Tool pos. = Quadrant transition at 270°

4: Tool pos. = Quadrant transition at 180°

Input: 0, 1, 2, 3, 4

Q203 Workpiece surface coordinate?

Coordinate on the workpiece surface referenced to the active datum. This value has an absolute effect.

Input: –99999.9999...+99999.9999

Q1030 Offset to surface?

Position of the upper edge of the tool on the surface. The offset serves as the overshoot path on the surface for the reciprocating stroke. This value has an absolute effect.

Input: 0...999.999

Q201 Depth?

Distance between the workpiece surface and the contour floor. This value has an incremental effect.

Input: –99999.9999...+0

Q1031 Machining direction?

Definition of the start position. The direction of the first reciprocating stroke arises from this.

–1 or 0: The starting position is on the surface. The reciprocating stroke begins in the negative direction.

+1: The starting position is at the cylinder floor. The reciprocating stroke begins in the positive direction.

Input: -1, 0, +1

Q1021 One-sided infeed (0/1)?

Position at which the lateral infeed occurs:

0: Lower and upper lateral infeed

1: One-sided infeed depending on Q1031

  • If Q1031 = -1, then the lateral infeed is performed above.
  • If Q1031 = +1, then the lateral infeed is performed below.

Input: 0, 1

Q534 Lateral infeed?

Amount by which the grinding tool is laterally infed.

Input: 0.0001...99.9999

Q1020 Number of idle strokes?

Number of idle strokes after the last lateral infeed without material removal.

Input: 0...99

Q1032 Factor for pitch of helix?

The pitch per helical path (= 360°) arises from the factor Q1032. Q1032 is multiplied by the width B of the grinding tool. The feed rate for the reciprocating stroke is influenced by the pitch of the helical path.

Input: 0.000...1000

Feed rate for the reciprocating stroke

Q207 Feed rate for grinding?

Traversing speed of the tool during grinding of the contour in mm/min

Input: 0...99999.999 or FAUTO, FU

Q253 Feed rate for pre-positioning?

Traversing speed of the tool when approaching the DEPTH Q201. The feed rate has an effect below the SURFACE COORDINATE Q203. Input in mm/min.

Input: 0...99999.9999 or FMAX, FAUTO, PREDEF

Q15 Up-cut / climb grinding (-1/+1)?

Define the type of contour grinding:

+1: Climb grinding

-1 or 0: Up-cut grinding

Input: -1, 0, +1

Q260 Clearance height?

Position at which no collision can occur with the workpiece. This value has an absolute effect.

Input: –99999.9999...+99999.9999 or PREDEF

Q200 Set-up clearance?

Distance between tool tip and workpiece surface. This value has an incremental effect.

Input: 0...99999.9999 or PREDEF

Q211 Idle runs at depth? (optional)

Number of idle runs at the lower reversal point of the reciprocating stroke.

Input: 0...99.99

Overshoot and idle runs to the reversal points of the reciprocating stroke

Q210 Idle runs at top? (optional)

Number of idle runs at the upper reversal point of the reciprocating stroke.

Input: 0...99.99

Overshoot and idle runs to the reversal points of the reciprocating stroke

NC programs contained in this User's Manual are suggestions for solutions. The NC programs or individual NC blocks must be adapted before being used on a machine.

Change the following contents as needed:

  • Tools
  • Cutting parameters
  • Feed rates
  • Clearance height or safe position
  • Machine-specific positions (e.g., with M91)
  • Paths of program calls

Some NC programs depend on the machine kinematics. Adapt these NC programs to your machine kinematics before the first test run.

In addition, test the NC programs using the simulation before the actual program run.

 
Tip

With a program test you determine whether the NC program can be used with the available software options, the active machine kinematics and the current machine configuration.

Example

11 CYCL DEF 1021 CYLINDER, SLOW-STROKE GRINDING ~

Q650=+0

;FIGURE TYPE ~

Q223=+50

;FINISHED PART DIA. ~

Q368=+0.1

;OVERSIZE AT START ~

Q14=+0

;ALLOWANCE FOR SIDE ~

Q367=+0

;POCKET POSITION ~

Q203=+0

;SURFACE COORDINATE ~

Q1030=+2

;VERSATZ OBERFLAECHE ~

Q201=-20

;DEPTH ~

Q1031=+1

;MACHINING DIRECTION ~

Q1021=+0

;ONE-SIDED INFEED ~

Q534=+0.01

;LATERAL INFEED ~

Q1020=+0

;IDLE STROKES ~

Q1032=+0.5

;FAKTOR ZUSTELLUNG ~

Q207=+2000

;GRINDING FEED RATE ~

Q253=+750

;F PRE-POSITIONING ~

Q15=-1

;TYPE OF GRINDING ~

Q260=+100

;CLEARANCE HEIGHT ~

Q200=+2

;SET-UP CLEARANCE ~

Q211=+0

;IDLE RUNS AT DEPTH ~

Q210=+0

;IDLE RUNS AT TOP