The present invention relates to a method to automatically general
program from AutoCAD drawing of a tube plate for a single/multi spindle CNC
drilling machine. More particularly, this invention relates to the automatic CNC
code generation from CAD drawing of a tube plate for multi spindle CNC drilling
operation. The tube plates are used in all heat exchangers for guiding series of
tubes in a defined pitch and pattern for better efficiency. For this the holes are
required to be drilled in a given pattern withthe specified pitch.The pattern and
Another object of the present invention is to propose a method to automatically
generate CNC program from AutoCAD drawing of a tube plate for a single/multi
spindle CNC drilling machine, which is able to generate tool path in virtual
environment and validate the correctness of the output.
BACKGROUND OF INVENTION
Seamless integration of design drawing to generate CNC part program is one such
area, where cycle time can be reduced. Product quality is enhanced as manual
intervention is reduced, thus errors are minimized.
The prior-art does not disclose any information directly related to this invention.
The patents WO2012111526A1, DE 698848C, EP1608905B1, US 2962805A

related to the present invention provide discrete information either related to
hole processing method and hole processing tools or tube sheet joint making.
But there is no mention of a method to automatically generate CNC code for
multi spindle CNC drilling from AutoCAD drawing.
A typical condenser plate generally consists of around 10,000 to 15000 holes with
different hole-layout patterns, depending on the design requirements. These holes
are drilled using four CNC drilling machines. At present, the hole layout comes in an
AutoCAD (ACAD) drawing format. From this drawing, a configuration file is
generated, by reading the number of holes in each row manually. The machine
movement, pitch between the holes and identification of the left out holes are done
manually for completing the drilling cycle in a row. From this configuration file, CNC
part programs are generated based on the machine configuration. This is very
tedious and time consuming task resulting in manual errors.
frp-iErrc nF THE INVENTION
Therefore, it is an object of the present invention to propose a method to
automatically generate CNC program from AutoCAD drawing of a tube plate for a
single/multi spindle CNC drilling machine, which is capable of generating CNC

program suitable to a defined multi spindle CNC machine automatically from
AutoCAD drawing.
Another object of the present invention is to propose a method to automatically
generate CNC program from AutoCAD drawing of a tube plate for a single/multi
spindle CNC drilling machine, which is able to generate tool path in virtual
environment and validate the correctness of the output.
A further object of the present invention is to propose a method to automatically
generate CNC program from AutoCAD drawing of a tube plate for a single/multi
spindle CNC drilling machine, which is capable of generating different post
processing tools suitable for defined CNC machine configuration and controller
specifications.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - Shows the exemplary method of generating off-line CNC program
using various steps.
Fig.2 - Shows the detailed methodology and steps involved in the process.

Fig.3 - Shows the programming device for generating the CAD model,
offline programming, CNC controller and CNC drilling machine.
Fig.4 - Shows the condenser plate drawing.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
A typical condenser tube plate [19] consists of around 10,000 to 15000 holes with
different hole-layout patterns depending on the design requirements, whereas a
feed water heater tube plate consists of around 6000 holes. These holes are being
drilled using multi spindle drill machines. These holes are in a defined pattern and
pitch [20] with respect to vertical or horizontal axis. The hole pattern, pitch
between the holes and depth of the hole varies from plate to plate depending on
the size and type of the heat exchanger. The plate consists of two types of holes
i.e., tube hole [21] and lifting hole [22] of different diameters.
These holes are drilled using multi spindle CNC drilling machines [18]. In
general, a multi spindle CNC drilling machine is having two to eight drilling
spindles. These spindles are arranged at defined pitch distance. If the distance
between two consecutive tube holes in a row is "x" mm, the pitch between two
spindles would be around "4X" mm. The configuration of CNC machines may

have individual spindle retract movement based on selection or simultaneous
movement of all the spindles. The drilling strategy changes depending on the
configuration.
The present invention establishes a system and a method to generate the CNC
code [5] for a defined CNC drilling machine [18] from the AutoCAD drawing [1]
of tube sheet. In this method, the AutoCAD drawing is imported in a CAD
environment [1]. A solid model is generated with the drawing. An algorithm
develops the suitable drilling strategy required for the multi spindle CNC [18]
drilling machine depending on its configuration and controller [17] settings. A
separate drilling strategy is created for drilling lifting holes separately.
The developed method takes ACAD drawing as Input [1] .From this drawing, it
extracts [2] the required information of hole data and formats it [4] in excel [3]
automatically, for generating the CNC code [5] suitable to a particular CNC
machine, with different multi spindle configuration. Separate CNC program for tie-
rod holes and left out holes [13] which are under clamping plates are generated
using this method. The method is also used for validation [6] of the CNC code [5]
prior to sending to the CNC machine controller [17], to eliminate any errors in the
generated code. The method is capable of re-generating CNC code for an in-
process work-piece, in case of machine breakdown or stops in between [10], by

taking input of last position of machine from the user. The method enables user to
generate error free CNC code according to the selected machine configuration and
reduces cycle time. Since the errors are minimized, the product quality will be good
and any mismatches during assembly of the product are eliminated.
After extracting data features of each hole, i.e., X, Y coordinates with respect to a
user co-ordinate system and diameter, the data is stored in an excel file and sorted
as per the constant pitch. The pattern is displayed on the screen for ensuring
selected ACAD drawing is the desired one or not.
By entering the required data in the data fields by the user, the method will
automatically generates a CNC program [5] suitable to the selected machine.
The eight spindle machine is having multiple options. If the first spindle of the
machine is under breakdown, [11] the next available spindle can be configured
as reference spindle or the same first spindle can be used as reference spindle
[12]. This enables the operator to use the machine with different spindle
configurations. The method also provides a provision for the user to select
number of clamping plates [9] required to hold the plate. The user has to enter
as to how many plates are being used and its length & width and position with
reference to center of the plate. The program automatically removes the holes
falling under this clamping plates and generates CNC program for the remaining

holes. A separate CNC program is generated for these left out holes and tie-rod
[13] holes as well.
One more method also has been devised to check for any errors in the
generated CNC code [6], and to validate the generated code. For this, the
generated CNC text file is taken as input. Using the input an AutoCAD layout is
generated in a different layer (Fig 6). This AutoCAD drawing is compared [14]
with the original drawing for any deviation and accordingly an error report is
generated [15]. If both the drawings match, then the CNC code from the PC [16]
to the CNC controller of the drilling machine is transferred. Otherwise, one looks
for the errors and the whole process is repeated [7].

WE CLAIM
1. A method to automatically generate CNC program from Auto CAD drawing of
a tube plate for a singte/multi spindle CNC drilling machine comprising;
importing an AutoCAD drawing of a tube plate in a CAD environment (1);
generating a solid model with the drawing;
developing a drilling strategy by an algorithm required for the multi-
spindle CNC (18) drilling machine depending on its configuration and
controller (17) setting;
creating a separate drilling strategy for drilling lifting holes separately;
wherein from ACAD drawing as input (1), the required information of hole
data is extracted and formatted (4) in excel (3) automatically to generate
CNC code (5) suitable to a particular CNC machine with different multi spindle
configuration, when separate CNC program for tie-rod holes and left out
holes (13) being under damping plates are generated, wherein the CNC code
(5) is validated (6) prior to sending to the CNC machine controller (17) to
eliminate any errors in the generated code, wherein an error free CNC code
according to the selected machine configuration with reduced cycle time and
enhance product quality is generated.