Large drilling machine, for example for simultaneous multiple drilling of a plate of a heat exchanger

Abstract

A large drilling machine (10) comprises an upright (106) and at least two spindle assemblies (108a, 108b, 108c). Each spindle assembly (108a, 108b, 108c) comprises a primary carriage (110), a secondary carriage (112), and a spindle (116). Furthermore, the drilling machine (10) comprises second axis detection means, adapted to detect the position of the spindle assembly (108a, 108b, 108c) along a second vertical translation axis (Y), and electronic management means. The electronic management means are configured or programmed to operatively couple the first motor (142' ) to the second motor (142'') of the second axis actuation means, so that the first motor (142' ) operates as a MASTER and the second motor (142'') operates as a SLAVE in position.

Description

"LARGE DRILLING MACHINE, FOR EXAMPLE FOR SIMULTANEOUSMULTIPLE DRILLING OF A PLATE OF A HEAT EXCHANGER" DESCRIPTIONField of the invention

[0001] The present invention is in the field of large machine tools . In particular, the present invention relates to a large drilling machine intended, for example, for the simultaneous multiple drilling of steel plates for heat exchangers , for example for nuclear power plants .Background of the invention

[0002] In some highly specialized sectors , such as for example in the manufacture of certain components for nuclear power plants , very strict machining tolerances are required, despite some components having considerable dimensions . For example, for the construction of a shell and tube heat exchanger, essentially consisting of an outer shell, two plates , and a tube bundle, the plate generally has a diameter of up to 5000 millimeters and is provided with 10 , 000-12 , 000 through holes for the insertions of the tubes ; each hole has a diameter between 8 and 60 millimeters , and extremely strict tolerances of positioning, diameter, linearity, and orthogonality with respect to the plane of the plate are required .

[0003] The heat exchanger provides for the passage of aradioactive carrier fluid on the primary side and water on the secondary side . The quality of the deep drilling with which the holes are made is essential for reliable and efficient operation .

[0004] For the simultaneous multiple drilling of such plates , large-sized and high-precision drilling machines are therefore required that are capable of ensuring very strict machining tolerances .

[0005] For years , the Applicant , for example, has been producing a drilling machine provided with three superimposed spindles , carried by a carriage that is translatable on a vertical upright . In a predefined position on the upright , the inclination of the carriage and the parallelism between the spindles are adjustable in order to register the orthogonality of the spindle axes with respect to the surface of the semi-finished product .

[0006] However, the drilling machines of the prior art involve long fine-tuning times due essentially to the need to perform measurements of a sample hole to check the actual attitude of the machine and then to arrange a multiplicity of shims and wedges to modify the attitude of the machine . Another sample hole is then drilled and measured and, if necessary, other shims and wedges are placed .

[0007] Examples of drilling machines are shown in US 4 752160 A, WO 2023 / 144613 Al and WO 2012 / 032423 Al .

[0008] Such machines are effective, but there is still a need to reduce the registration time in order to reduce the overall time for drilling, to the benefit of the production economy .Object of the invention

[0009] The object of the present invention is to provide a large-sized drilling machine, for example for drilling components of nuclear power plants , such as shell and tube heat exchanger plates , which allows the fine-tuning time to be reduced and ensure stable performance over time .

[0010] This object is achieved by a drilling machine according to claim 1 . The dependent claims disclose further advantageous embodiments of the invention .Brief description of the drawings

[0011] The features and the advantages of the drilling machine according to the present invention will appear more clearly from the following description, made by way of an indicative and non-limiting example according to the drawings of the accompanying figures , in which :- Fig . 1 shows a drilling machine according to one embodiment of the present invention;- Fig . 2 is a spindle assembly of a drilling machineaccording to an embodiment of the present invention;- Fig . 3 is the spindle assembly of Fig . 2 , according to a further point of view;- Fig . 4 depicts a spindle assembly in a first working configuration or initial configuration; and- Fig . 5 depicts the spindle assembly of Fig . 4 in a second working configuration or final configuration .Detailed description of embodiments of the invention

[0012] With reference to the figures in the attached drawings , 1 has been used to indicate a drilling apparatus for drilling a working surface of a semifinished product , for example for drilling a plate for a heat exchanger .

[0013] The drilling apparatus 1 comprises a horizontal reference plane T, a pit 2 made below the height identified by the reference plane T, a drilling machine 10 placed in the pit 2 , a working region 20 for supporting the semi-finished product , in turn comprising a piece-holder table 30 usually coplanar with the reference plane T, and a control group 40 for the electrical power supply, actuation, and control of the drilling machine 10 .

[0014] The drilling machine 10 comprises a base 102 (not shown in the figures ) , preferably contained in the pit 2 , an upright carriage 104 supported by the base 102 andtranslatable in a controlled manner thereon along a first horizontal translation axis X through first axis actuation means , an upright 106 supported by the upright carriage 104 , a plurality of vertically superimposed spindle assemblies 108a, 108b, 108c in a direction perpendicular to the first translation axis X and supported by the upright 106 .

[0015] The drilling machine 10 comprises at least two spindle assemblies 108a, 108b, 108c .

[0016] Each spindle assembly 108a, 108b, 108c comprises a primary carriage 110 which is translatable in a controlled manner on the upright 106 along a second vertical translation axis Y .

[0017] For example, the primary carriage 110 consists of a box-like body extending along a main horizontal direction between a front end 110 ' , facing the working region 20 , and an opposite rear end 110 ' ' ; the primary carriage 110 also has a side surface extending between the front end 110 ' and the rear end 110 ' ' , having in particular an inner face 110a facing the upright 106 and an opposite outer face 110b .

[0018] Furthermore, each spindle assembly 108a, 108b, 108 c comprises a secondary carriage 112 applied to the outer face 110b of the primary carriage 110 , which is translatable on command along a third translation axis Z ,orthogonal to the first translation axis X and the second translation axis Y .

[0019] Each spindle as sembly 108a, 108b, 108c further comprises third axis actuation means comprising at least one third axis motor 114 , for example electrically actuated, arranged on board the primary carriage 110 , preferably with a rotor axis parallel to the third translation axis Z , configured to translate the secondary carriage 112 along the third translation axis Z , for example by means of a recirculating ball screw system .

[0020] Furthermore, each spindle assembly 108a, 108b, 108 c comprises a spindle 116 carried by the secondary carriage 112 , and spindle rotation actuation means , for example comprising a spindle motor 117 , for example electrically actuated, arranged on board the secondary carriage 112 , preferably rotationally actuatable with the rotor axis parallel to the third translation axis Z , configured to rotate a drilling bit 118 about a rotation axis S, parallel to the third translation axis Z . The drilling bit 118 is engaged to the spindle 116 and is adapted to carry a drilling tool to a front end .

[0021] Furthermore, each spindle assembly 108a, 108b, 108 c comprises a feeding head 120 configured to support the drilling bit 118 at the front , applied to the outer face 110b of the primary carriage 110 , translatable on commandalong a fourth translation axis W, parallel to the third translation axis Z .

[0022] Each spindle as sembly 108a, 108b, 108c comprises fourth axis actuation means comprising at least one fourth axis motor 121 , for example electrically actuated, arranged on board the primary carriage 110 , preferably with a rotor axis parallel to the third translation axis Z , configured to translate the feeding head 120 along the fourth translation axis W, for example by means of a recirculating ball screw system .

[0023] Finally, each spindle assembly 108a, 108b, 108c comprises a steady rest 122 configured to support the drilling bit 118 between the spindle 116 and the feeding head 120 , applied to the outer face 110b of the primary carriage 110 , translatable on command along an axis parallel to the third translation axis Z .

[0024] Each spindle as sembly 108a, 108b, 108c comprises steady rest movement means comprising, for example, a pneumatic piston 123 , calibrated at a predefined pressure, integral translationally with the secondary carriage 112 and protruding therefrom at the front , until it interacts with the steady rest 122 , pushing it towards the feeding head 120 during a forward stroke of the secondary carriage 112 and pulling it from the feeding head 120 during a return stroke of the secondary carriage112 .

[0025] Each spindle assembly 108a, 108b, 108c is configured to perform a deep drilling both in BTA mode (Boring and Trepanning Association, sometimes referred to as STS - Single Tube System) , and in "gun drilling" mode .

[0026] Each spindle as sembly 108a, 108b, 108c further comprises guide means engaged with the upright to guide the primary carriage 110 in the translation along the second translation axis Y . Said guide means comprise at least one first guide shoe 131 ' and one second guide shoe 131 ' ' , both fixed to the inner face 110a of the primary carriage 110 and spaced apart in a direction parallel to the third translation axis Z . Preferably, each guide shoe 131 ' , 131 ' ' comprises two guide sections 132 , 134 , superimposed in the direction of the second translation axis Y and aligned with each other .

[0027] Each spindle as sembly 108a, 108b, 108c further comprises second axis braking means actuatable to engage the upright and brake the translation of the spindle assembly 108a, 108b, 108c along the second translation axis Y . Said second axis braking means comprise a first brake 136 ' and a second brake 136 ' ' , both fixed to the inner face 110a of the primary carriage 110 and spaced apart in a direction parallel to the third translation axis Z . Preferably, the brakes 136 ' , 136 ' ' are arrangedbetween the shoes 131 131

[0028] Furthermore, preferably, a first compartment 135' and a second compartment 135' ' are obtained on the inner face 110a of the primary carriage 110, spaced apart in a direction parallel to the third translation axis Z, for example side by side with one of the shoes 131', 131' ' or with one of the brakes 136' , 136' ' . For example, the first compartment 135' is arranged between the first shoe 131' and the first brake 136', while the second compartment 135' ' is placed alongside the second shoe 131' ', on the opposite side of the second brake 136' ' . The compartments 135', 135' ' are adapted to at least partially accommodate the shoes of another spindle assembly .

[0029] In fact, preferably, the shoes 131', 131' ' protrude above and / or below the primary carriage; in order to move the spindle assemblies when they are superimposed as close together as possible along the second translation axis Y, it is therefore necessary for the shoes of a first spindle assembly to be at least partially accommodated in the respective compartments of a second spindle assembly. For example, when two spindle assemblies 108a, 108b, 108c are present, the shoes of the first spindle assembly are at least partially accommodated in the respective compartments of the secondspindle assembly.

[0030] A first guide and braking assembly 130' comprises a first support 138', to which the first shoe 131' and the first brake 136' are fixed; the first support is in turn fixed in a recess of the rear face 110a of the primary carriage 110. Preferably, the first compartment 135' is formed in said first support 138' . Similarly, for a second guide and braking assembly 130' ' .

[0031] Each spindle assembly 108a, 108b, 108c further comprises second axis actuation means, for moving the primary carriage 110 translationally on the upright 106 in a controlled manner along a second vertical translation axis Y, comprising a first actuation assembly 140' and a second actuation assembly 140' ', which are actuatable to move the primary carriage translationally in a controlled manner along the second translation axisY.

[0032] The first actuation assembly 140' comprises a first motor 142', preferably electric, with a rotor axis parallel to the direction of the third translation axisZ, a first reducer 144' and a first pinion, preferably helical, adapted to engage with a relevant rack provided on the upright 106. Similarly, the second actuation assembly 140' ' comprises a second, preferably electric, motor 142' ' with a rotor axis parallel to the directionof the third translation axis Z, a second reducer 144' ', and a second pinion 146' ', preferably helical, adapted to engage with a relevant rack provided on the upright 106.

[0033] Both actuation assemblies 140', 140' ' are supported by the inner face 110a of the primary carriage 110, spaced apart in a direction parallel to the third translation axis Z. For example, said guide and braking assemblies 130', 130' ' are arranged between the actuation assemblies 140', 140' ' . Furthermore, preferably, the first reducer 144' is fixed to the first support 138', and the second reducer 144' ' is fixed to the second support 138 ' ' .

[0034] In summary, each spindle assembly 108a, 108b, 108c comprises at least one primary carriage 110 and one secondary carriage 112 supported by the primary carriage 110, second axis actuation means, a spindle 116, and a drilling bit 118.The drilling machine 10 further comprises second axis detection means adapted to detect the position of each spindle assembly 108a, 108b, 108c along the second translation axis Y; for example, said second axis detection means comprise a position transducer, such as an optical ruler, wherein the ruler is fixed to the upright and the slider is on board the primary carriage.

[0035] The drilling machine 10 further comprises electronicmanagement means operatively connected to the second axis detection means and to the second axis actuation means for processing signals generated by the second axis detection means and actuating the second axis actuation means until a predefined height along the second translation axis Y is reached .

[0036] Furthermore, the electronic management means are operatively connected to the second axis braking means for locking the primary carriage at said predefined height along the second translation axis Y .

[0037] For each spindle assembly 108a, 108b, 108c, the electronic management means are configured or programmed to operatively couple the first actuation assembly 140 ' to the second actuation assembly 140 ' ' of the second axis actuation means , so that the first actuation assembly operates as a MASTER and the second actuation assembly operates as a SLAVE in position .

[0038] At a predefined height along the second translation axis Y, each spindle assembly 108a, 108b, 108c assumes two configurations during normal operation :- a first configuration or initial configuration (Fig . 4 ) , in which the drilling is incipient ; in this configuration, the end of the drilling bit 118 is substantially in contact with the surface of the semifinished product , the secondary carriage 112 is in aninitial carriage position, distal from the front end110' ' of the primary carriage 110, the feeding head 120 is in an initial feeding head position proximal to the front end 110' ' of the primary carriage 110, and the steady rest 122 is arranged between the spindle 116 and the feeding head 120, for example halfway between them, in a position distal from the front end 110' ' of the primary carriage 110;- a second configuration or final configuration (Fig. 5) , in which the drilling is completed; in this configuration, the secondary carriage 112 is in a final carriage position, proximal to the front end 110' ' of the primary carriage 110, the feeding head 120 is in a final feeding head position generally identical to the initial feeding head position, i.e. proximal to the front end 110' ' of the primary carriage 110, and the steady rest 122 is arranged between the spindle 116 and the feeding head 120, in a position proximal to the front end 110' ' of the primary carriage 110.

[0039] Between the first configuration and the second configuration there is therefore a different mass distribution on each spindle assembly, since some significant components, such as the secondary carriage with the spindle, the feeding head, and the steady rest, in the final configuration are closer to the front end ofthe primary carriage than in the initial configuration.

[0040] According to a first embodiment, the machine undergoes a static fine-tuning, as described below.

[0041] For each spindle assembly, for a series of predefined heights Yl-Yn, e.g., minimum, intermediate, and maximum, for a series of predefined configurations Cl-Cm, e.g., the initial configuration and the final configuration, a reference parameter Pij, in which i=l..n and j=l...m, e.g., the inclination of the primary carriage 110 with respect to the reference plane T, is detected and entered manually.

[0042] For a predefined height Y* , defined as the design height, of the set of predefined heights Yl-Yn, e.g., the maximum height, and a predefined configuration C* , defined as the design configuration, of the set of predefined configurations Cl-Cm, e.g., the final configuration, the value of the parameter P* is provided to the electronic management means for correcting the positioning of each spindle assembly 108a, 108b, 108c along the second translation axis.

[0043] According to a second embodiment, the machine undergoes a dynamic fine-tuning, as described below.

[0044] In such an embodiment, each spindle assembly 108a, 108b, 108c comprises a parameter sensor adapted to detect a predefined parameter P related to the spatialarrangement assumed by the primary carriage 110 ; for example, said sensor is an inclinometer and is configured to detect the inclination assumed by a reference surface of the primary carriage with respect to the reference plane T . Said parameter sensor is operatively connected to the electronic management means for processing said parameter P .

[0045] For each spindle assembly, for a series of predefined heights Yl-Yn, e . g . , minimum, intermediate, and maximum, for a series of predefined configurations Cl-Cm, e . g . , the initial configuration and the final configuration, the parameter sensor detects the reference parameter Pi j , in which i=l . . n and j=l . . . m .

[0046] The values of the reference parameters Pi j define a correction matrix M= [Pij ] supplied to said electronic management means for correcting the positioning of each spindle assembly 108a, 108b, 108c along the second translation axis , as a function of the heights Yl-Yn and the configurations Cl-Cm assumed thereby .

[0047] Innovatively, the drilling machine according to the present invention meets the needs of the industry and overcomes the drawbacks mentioned with reference to the prior art , as it allows a simplified and quick registration with respect to the surface of the semifinished product to be processed . For clarity ofdescription, reference has been made in the foregoing description to a drilling machine comprising three spindle assemblies . However, it is understood from the description how the invention is applicable to a drilling machine comprising a single spindle assembly .

[0048] It is clear that those skilled in the art , in order to meet specific needs , may make changes to the drilling machine described above, all of which fall within the scope of protection defined in the following claims .

Claims

CLAIMS1. A drilling machine (10) comprising an upright (106) and at least two spindle assemblies (108a, 108b, 108c) supported by the upright (106) , wherein the spindle assembly (108a, 108b, 108c) comprises:- a primary carriage (110) and second axis actuation means actuatable to translationally move the primary carriage (110) on the upright (106) in a controlled manner along a second vertical translation axis (Y) , wherein the second axis actuation means comprise a first motor (142' ) and a second motor (142' ' ) , supported by the primary carriage;- a secondary carriage (112) supported by the primary carriage (110) translationally actuatable in a controlled manner along a third horizontal translation axis (Z) , said first motor (142' ) and second motor (142' ' ) of the second axis actuation means being operational on the upright at a predetermined distance in the direction of the third translation axis (Z) ;- a spindle (116) rotationally actuatable about a rotation axis (S) parallel to the third translation axis (Z) and a drilling bit (118) engaged with the spindle (116) adapted to carry a drilling tool at a front end; wherein the drilling machine further comprises:- second axis detection means adapted to detect theposition of the spindle assembly (108a, 108b, 108c) along the second translation axis (Y) , and- electronic management means operatively connected at least to the second axis detection means and the second axis actuation means for processing signals generated by the second axis detection means and actuating the second axis actuation means until the primary carriage (110) reaches a predetermined height (Y*) along the second translation axis (Y) ; and wherein the electronic management means are configured or programmed to operatively couple the first motor (142' ) to the second motor (142' ' ) of the second axis actuation means, so that the first motor (142' ' ) operates as a MASTER and the second motor (142' ' ) operates as a SLAVE in position.

2. A drilling machine (10) according to claim 1, wherein the electronic management means are configured or programmed to actuate the second axis actuation means as a function of a reference parameter (Pij) or a correction matrix M=[Pij] related to the spatial arrangement of the spindle assembly, for example the inclination of a reference surface of the primary carriage.

3. A drilling machine (10) according to claim 2, wherein the reference parameter (Pij) or the correction matrix M=[Pij] can be entered manually to make them available tothe electronic management means.

4. A drilling machine (10) according to claim 2, wherein the spindle assembly (108a, 108b, 108c) comprises a parameter sensor adapted to detect said reference parameter (Pij) or correction matrix (M=[Pij]) .

5. A drilling machine (10) according to claim 4, wherein the parameter sensor is operatively connected to the electronic management means to transmit said reference parameter (Pij) or correction matrix M=[Pij] .

6. A drilling machine (10) according to any one of the preceding claims, wherein the spindle assembly (108a, 108b, 108c) comprises second axis braking means actuatable to engage the upright and brake the translation of the spindle assembly (108a, 108b, 108c) along the second translation axis (Y) , wherein the second axis braking means comprise a first brake (136' ) and a second brake (136' ' ) , operating on the upright at a predetermined distance in the direction of the third translation axis (Z) .

7. A drilling machine (10) according to claim 6, wherein the electronic management means are operatively connected to the second axis braking means to lock the spindle assembly (108a, 108b, 108c) at the predetermined height (Y*) along the second translation axis (Y) .

8. A drilling machine (10) according to any one of thepreceding claims, wherein the spindle assembly comprises a feeding head (120) configured to support the drilling bit (118) at the front, translatable on command along a fourth translation axis (W) , parallel to the third translation axis (Z) .

9. A drilling machine (10) according to claim 8, wherein the spindle assembly comprises a translatable steady rest (122) configured to support the drilling bit (118) between the spindle (116) and the feeding head (120) .

10. A drilling machine (10) according to any one of the preceding claims, wherein the spindle assembly comprises guide means engaged with the upright to guide the primary carriage (110) in the translation along the second translation axis (Y) , said guide means comprising at least a first guide shoe (131') and a second guide shoe (131' ' ) fixed to the primary carriage (110) and spaced apart in the direction of the third translation axis (Z) .

11. A drilling machine (10) according to any one of the preceding claims, comprising a plurality of spindle assemblies (108a, 108b, 108c) , vertically superimposed and supported by the upright (106) .

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