Tool driving or impacting – Processes
Reexamination Certificate
1999-02-02
2001-07-10
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Processes
C173S002000, C173S004000, C173S019000, C408S0010BD, C408S056000
Reexamination Certificate
active
06257348
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control apparatus for a drilling machine and to a drilling method, more particularly relates to a control apparatus for a drilling machine and a drilling method applicable to drills of various diameters and especially suitable for drilling by small diameter drills.
2. Description of the Related Art
A workplece is drilled by a numerical control (NC) machine by attaching a drill to a spindle of the machine and moving it in a predetermined direction with respect to the workpiece fixed to a table while making the spindle rotate.
A “drill” is a cutting tool having a cutting edge on its tip and a flute on its body for cutting a hole. Here,
FIGS. 1A and 1B
show an example of a conventional method of drilling a workpiece. As shown in
FIG. 1A. a
center drill
102
is attached (mounted) to a spindle of a machining center of other NC machine tool. The center drill
102
is moved down to a workpiece W of a thickness H while rotating at a predetermined speed to form a prepared hole
103
in the workpLece W. This prepared hole
103
facilitates the start of the drilling of the workpLece W by the drill
104
for the main drilling.
Next., the center drill
102
is detached from the spindle. As shown in
FIG. 1B
, the drill
104
for the main drilling is attached to the spindle, rotated at a predetermined speed, and moved down to the workpiece W at a predetermined feed speed for cutting a hole
105
through the prepared hole
103
formed in the previous step.
At this time, the hole
105
is cut by the drill
104
by repeatedly moving the drill
104
down to the workpiece W to out it by a depth of cut S, moving the drill
104
outside of the hole
105
, then again cutting by the depth of cut S. As a result of the above operation, a hole
105
is formed passing through the workpiece W of the thickness H. Note that the repeated cutting by the depth of cut S is for chip relief from the hole
105
.
The above drilling method is performed by making an NC apparatus controlling the NC machine tool program execute an NC program which defines the speed of a spindle, the cutting feed speed, the depth of out S, the depth of the hole
105
, and other factors.
In the above conventional drilling process, however, an NC program defining the depth of cut and the depth of the hole must be prepared for each different drilling process. Therefore, when drilling a variety of holes, troublesome work is involved and it is necessary to change the NC program to change the cutting conditions.
Note that the above drilling method was designed for forming holes having a large diameter, for example, a diameter larger than 0.5 mm. Therefore, various problems arise when applying small diameter drills of a diameter of less than 0.5 mm as they are to the above drilling method.
That is, when drilling by a small diameter drill, a small diameter drill will sometimes break when repeatedly cutting by a depth of cut S due to interference between the small diameter drill and the hole.
When drilling a through hole through a workpiece W by a small diameter drill, furthermore, the small diameter drill will sometimes easily shift from the center of the hole and break when passing through (breaking through) the workpiece W.
Furthermore, when using a small diameter drill to drill a hole through a workpiece W, the above prepared hole
103
is not formed in the workpiece W. that is, the hole is drilled by a single small diameter drill, so there is the danger of poor starting of drilling of the small diameter drill in the workpiece W.
Also, when the material of the workpiece W is a stainless steel or another heat resistant steel, the small diameter drill is heated during the cutting of the workplece W. This heat makes the small diameter drill more susceptible to breaking.
When forming a small diameter hole, therefore, it is therefore especially necessary to prepare an NC program designating the optimal cutting conditions for every drilling process.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a control apparatus for a drilling machine and a drilling method enabling quite handling of drilling by drills of various diameters, especially drilling by small diameter drills, and enabling improvement of the cutting efficiency.
According to a first aspect of the present invention, there is provided a control apparatus for a drilling machine comprising a rotating means for rotating a drill; a moving means for making the drill move relative to a workpiece; a cutting condition setting means for defining setting a plurality of cutting regions of a hole in accordance with a depth of the hole and independently setting cutting conditions for each cutting region; and a control means for controlling the rotating means and the moving means in accordance with the cutting conditions.
Preferably, the cutting condition setting means has: a cutting region setting means for setting a plurality of cutting regions in accordance with the depth of the hole; a cutting feed speed setting means for independently setting cutting feed speeds of the drill for each cutting region; a non-cutting feed speed setting means for independently setting feed speeds of the drill for each cutting region; a depth of cut setting means for independently setting one depth of cut for each cutting region; an interference prevention condition setting means for preventing interference between the drill and the hole when cutting into the workpiece again after cutting by a predetermined depth of cut; and a drill rotary speed setting means for independently setting a rotary speed of the drill for each cutting region.
Alternatively, preferably, cutting condition setting means further has a cooling condition setting means for setting cooling conditions when moving the drill outside said hole to cool it so as to relieve heat generated in the drill by cutting.
Alternatively, preferably, cutting condition setting means further has a spindle dwell time setting means for setting a time for keeping the drill waiting without cutting until the rotary speed of the spindle reaches a desired rotary speed.
Alternatively, preferably, the cutting region setting means defines a beginning part, an inner part, and a penetration part in accordance with the depth of the hole from the side close to the drill of the workpiece toward a depth direction of the hole in the workpiece.
More preferably, the interference prevention condition setting means sets a clearance between the previous cutting depth position and the current cutting beginning position.
Alternatively, more preferably, the cooling condition setting means sets a waiting time to keep the drill waiting after moving the drill outside of the hole when cutting the plurality of cutting regions.
According to a second aspect of the present invention, there is provided a drilling method including the steps of dividing a hole to be drilled in a workpiece into cutting regions of a beginning part, an inner part, and a penetration part and independently setting cutting conditions for each cutting region, cutting the beginning part based on the cutting conditions for the beginning part; cutting the inner part based on the cutting conditions for the inner part; and cutting the penetration part based on the cutting conditions for the penetration part.
Preferably, the step of dividing the hole and setting cutting conditions includes a step of independently setting at least one of one depth of out of the drill, a cutting feed speed of the drill, a rotary speed of the drill, and a non-cutting feed speed of the drill for each cutting region.
Preferably, at least one of the steps has at least one of a step of starting the cutting by the drill from a previous cutting depth position a predetermined distance away when drilling the hole by a plurality of cuttings by a predetermined depth of cut and a step of moving the drill outside the hole after cutting by the predetermined depth of out and cooling the drill by idle spinning for a predetermined time.
Preferably, t
Matumoto Michio
Momochi Takeshi
Sagara Makoto
Shiozaki Masahito
Sugiyama Haruhito
Pillsbury & Winthrop LLP
Smith Scott A.
Toshiba Kikai Kabushiki Kaisha
LandOfFree
Control apparatus for drilling machine and drilling method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control apparatus for drilling machine and drilling method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control apparatus for drilling machine and drilling method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2487561