US2999550A

US2999550A - Drilling machine

Info

Publication number: US2999550A
Application number: US693475A
Authority: US
Inventors: Gerentes Jean
Original assignee: CONST ELECTRO MECANIQUES DE SA
Current assignee: CONST ELECTRO MECANIQUES DE SA; CONSTRUCTIONS ELECTRO-MECANIQUES DE SAINT-ETIENNE
Priority date: 1956-10-31
Filing date: 1957-10-30
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

Sept. 12, 1961 J. GERENTES DRILLING MACHINE 4 Sheets-Sheet 1 Filed Oct. 30, 1957 lllll III lllll H Sept. 12, 1961 J. GERENTES 2,999,550

DRILLING MACHINE Filed Oct. 50, 1957 4 Sheets-Sheet 2 1 /////A//////////////////////A '|||||||l||||||llIllIlllIlllllllml|||||[Illlllllllllllllllllllllll lllllllllllllllllIIIIllllllllllllllllllllllIIIIIIIIIIIIIIIIII WWEWWMWWIWIWW Sept. 12, 1961 J. GERENTES DRILLING MACHINE 4 Sheets-Sheet 3 Filed Oct. 50, 1957 mmmmmm E Sept. 12, 1961 .1. GERENTES DRILLING MACHINE 4 Sheets-Sheet 4 Filed Oct. 30, 1957 W i W a W mo bk; eww MIWWO m1 ,0 6 e i a w. @LW M W .n I w MAW w a V.

Z h m F FM P E H 2,999,550 DRILLING MACHINE Jean Gerentes, Saint-Etienne, France, assignor to Constructions Electro-Mecaniques de Saint-Etienne (Ancienne Usine Wageor), Saint-Etienne, France, a corporation of France Filed Oct. 30, 1957, Ser. No. 693,475 Claims priority, application France Oct. 31, 1956 1 Claim. (Cl. 175-33) The present invention relates to variable-feed electric drilling machines.

The applicant has already proposed a type of drilling machine in which the drill-bit is rotated by a main motor whereas its longitudinal movements result from the action of this main motor and of an auxiliary reversible motor, the main motor driving, in addition to the bit-carrying shaft, one of two members consisting of a nut and screw, the other of these two members being driven by the auxiliary motor, so that feed of the bit results from the difierence between the rotational speeds of the screw and nut. Further, these motors have different mechanical characteristics (torque C-speed N), that is dilierent slips, the slip of the aum'liary motor being the greater, which is easily obtained with a squirrel-cage asynchronous motor by increasing the resistance of the cage. Thus, as the developed torques are a function of the hardness of the rock being drilled, the difierence in the speeds of the two driven members decreases when rock hardness increases and this reduces the feed and reduces the load on each of the two motors.

For example, if the auxiliary motor drives the faster of said two members at a speed N and the main motor the other member at a slower speed N the feed of the drill-bit is a- 1) XP where p is the lead of the screw.

By construction, when the hardness of the rock increases, the difference (N -N decreases, since, as the torque increases for each of the motors, the slip of the auxiliary motor increases much more rapidly than that of the main motor.

However, it could occur that in very marly ground where there is considerable friction on the periphery of the drill-bit or there is difliculty in evacuating the drilled away matter, the speed N of rotation of the main motor decreases considerably as a result of the high load. Thus, N decreases much more rapidly than N so that when (N -N increases instead of decreasing the speed of drill feed increases which tends still more to increase the load and thus still more throws the system out of equilibruim. Wedging could occur and the considerable forces developed could cause the destruction of the component parts.

The object of the invention is to remedy this disadvantage.

The invention provides an electric drilling machine of the aforementioned type, characterised in that it is so arranged as to comprise a plurality of speed ranges and is combined with a control device permitting an automatic speed range change in accordance with the type of ground being drilled.

In a preferred embodiment, the auxiliary motor comprises at least two inductance or stator windings having a different number of poles.

If, for example, the auxiliary motor comprises two windings having respectively four and six poles, when operating on four poles, the drill feed is (N -N X p, whereas when operating on six poles, it is only d States Patent Q Preferably, the supply circuits of the sole winding of the main motor and the windings of the auxiliary motor are combined with an electromechanical control device comprising manually-operated contactors permitting a manual control of the drill feed, and an automatic control means permitting an automatic change in the speed of the auxiliary motor, and thus in the longitudinal displacement of the drillbit, in accordance with the intensity of the current consumed by the main motor.

Advantageously, this automatic control means could be an overcurrent relay disposed in the main motor supply circuit and the electric control circuits are so arranged that the winding corresponding to the greater number of poles of the auxiliary motor is put in circuit as soon as a given maximum intensity is reached in the main motor supply circuit.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings, to which the invention is in no way limited.

In the drawings:

FIG. 1 is a diagrammatic view in elevation, with a part cut away, of a drilling machine embodying the invention;

FIG. 2 is a partial longitudinal sectional view on an enlarged scale of the auxiliary motor and a part of the main motor;

FIG. 3 is a diagrammatic front View, with a part of the wall cut away, of th erelay box of the drilling machine;

FIG. 4 is a side view of the relay box, and

FIG. 5 is a diagram of the electrical connections.

In the embodiment shown in FIGS. 1 to 3, the drilling machine comprises a stand comprising two parallel longitudinal roiled-section members 10 along which is movable an electrical motor M whose output shaft 12 is connected to a drill-bit carrier 13 by a gear train 14-, 15, 16, 17; the gears 15 and 16 are keyed to an idle shaft 18 to which is secured a third gear 19. The carrier 13 carries the drill-bit or tool 20 which is guided by a fixed bushing 21 and a movable bushing 22.

Fixed at the rear end of the stand is an auxiliary motor M whose output shaft 23 (FIG. 2) is connected, by means of a speed-reducing gear train 24, 25, to the end of a longitudinal screw 26. The latter is fixed as concerns movement in the direction of its axis but it is journalled in the stand. Screw-threadedly engaged thereon is a nut 27 which is journalled in the housing of the motor M so as to drive the latter along the screw 26 in accordance with the difference between the speeds N and N of the screw and this nut, the latter being driven by the motor M through the gear 19 meshed with a gear 28 which is coaxial and rigid with the nut.

The motors M and M are three-phase motors and are so designed that the slip of motor M is greater than that of the motor M their slips being preferably about 5 and 15% respectively. The motor M having the greater slip, could be in particular a squirrel-cage asynchronous motor wherein the slip is a function of the resistance of the bars of the cage and is the greater as this resistance is higher.

The main motor M is a motor having a single winding, as can be seen at 29 in FIG. 2, whereas the motor M: has two windings 3i) and 31 having, for example, four and six poles corresponding to speeds N and respectively.

cables 35 connect the box 33 to the drilling machine and the two cables 36 connect this box to the box 32. Each cable has of course several conductors.

I It will be observed from the diagram shown in FIG. that the various relays are designated by roman reference characters I to VIII and the corresponding contacts by arab reference characters 1 to 7; the various contacts pertaining to the same relay are distinguished by an exponent character. Thus contacts 2 2*, 2 are provided for the relay II.

The push button contactors are designated by capital letters, A, B F.

The power supply is three-phase and the supply cable 34 therefore comprises three conductors L L and L each of which corresponds to a phase.

The motor circuits will first be described.

Main motor M .-The three phases, 40, 41 and 42 are star connected; the conductor 40 is connected to the phase L through the contact 2 (a contact of the relay II); the conductor 41 is connected to the phase L through the contact 2 and the conductor 42 is connected to the phase L either through the coil 43 of the overcurrent re lay I or through a bypass contact 7, this coil 43 and this contact being both series connected with the contact 2.

Auxiliary motor M .-The

high speed windings

44, 45 and 46 are star connected and the same is true of the windings 47, 48 and 49 corresponding to the low speed.

The windings 44 and 45 are connected to the phases L and L through the contacts 4, 5 and 5 4 respectively. The winding 46 is connected to the phase L; by either one of two contacts 4, 5.

The windings 47, 48 and 49 are connected to phases L L and L through contacts 3 3 and 3 respectively.

Description will not be given of the initial excitation circuits and then the maintenance circuits of the relays II to VIII (the overcurrent-relay I circuit has been described hereinbefore). These relays having coils 50 to 56 are combined on the one hand with the following push button contactors biased by springs:

A corresponding to stoppage of the drilling,

B corresponding to the start of the drilling,

C corresponding to a reduced drill feed,

D corresponding to stoppage of the drill feed,

E corresponding to the return rearward movement of the drill-bit by reversing the direction of rotation of the motor M power being supplied to the windings for operation at normal speed.

F corresponding to the two contacts F and F of the manually controlled passage from drill feed at reduced speed to feed at normal speed.

Said relays having coils 50 to 56 are furthermore combined with a switch G corresponding to the end of forward drill travel and switch H corresponding to the end of rearward travel. These switches are at the base of the diagram shown in FIG. 5 and near the ends of the stand 10 shown in FIG. 1.

The relay circuits are as follows:

Relay I.-This relay is series connected with one of the branch conductors of the motor M Relay II corresponding to the start of drilling by way of its contacts 2*, 2 and 2. Its main supply circuit is: phase L stop contactor A, contactor B corresponding to the start of drilling, point a, the winding 50, switch H corresponding to the end of rear drill travel, and phase Its maintenance circuit is: L switch A, point 5, contact 2 winding 50, switch H, phase L Relay III controlling the drill feed at reduced speed through the contacts 3*, 3 and 3. Its excitation circuit is: L reduced speed drill feed contactor C, winding 51, contact 5 end of forward travel switch G, L

Its maintenance circuit is: L contactor D corresponding to stoppage of the forward drill feed, point c, contacts 4 6, 4 first contact F of the double contactor F, winding 51, contact 5 end of forward travel switch G, L

Relay IV controlling drill feed at normal speed through the contacts 4 4*, 4. Its excitation circuit is: L the second contact F of the double contactor F, point d, cont-actor 3 winding 52, contact 5 switch G, L

The maintenance circuit is: L contactor D, point c, contacts 4 6 3 winding 52, contact 5 switch G, L

Relay V controlling the reverse drill travel. Its excitation circuit is: L contactor E corresponding to reverse operation, point e, contacts 3e, 4 53, reverse operation switch H, L whereas its maintenance circuit is by way of the contact 5*.

Relay VI.--This relay is an auxiliary relay whose excitation circuit is: L stoppage contactor A, point b, contacts 8 2', winding 54, contact 5 end of forward travel switch G, L

RELAY VII.-This relay is adapted to short-circuit the relay I by closing the contact 7 Its excitation circuit is: L the contact P of the double contactor F, point d, contact 3 winding 55, end of reverse travel switch H, L

Relay VIII.--This is :an auxiliary relay whose excitation circuit is: L stoppage contactor A, contactor corresponding to the start of drilling B, contact 1 of the relay I, contact 3 winding 56, contact 5 end of forward travel switch G, L

The following table illustrates the positions of the various contacts when the windings of the relays are not energized, the conditions of these contacts being reversed after energization of the relays.

Table Winding not energized Winding N o. of relay of Relay Contacts Contacts open closed The machine operates in the following manner:

When the machine is inoperative, the contactors and contacts are in the positions in the diagram shown in FIG. 5.

Elements A, D, F 7 8*, 3 6', 4 3, 4 3, 1, 5 are closed. The switches G and H are also closed and the carrier 13 is shown to be in an intermediate position in its travel (FIG. 1).

All the other contactors and contacts are open.

To perform a drilling operation the following successive operations are effected:

1) The push button of the contactor B is depressed. The motor M is thereby started. As the contactor A is closed, the relay II is excited through the circuit L A, B, 50, H, L and maintained excited when the contactor is released by its maintenance circuit through the contact 2 which is closed by the initial excitation. The contactor A remains excited until the end of one operational cycle. The auxiliary relay VIII is excited at the same time and opens the contact 8 which prevents excitation of the auxiliary relay VI.

(2) The push button C, corresponding to the start of forward drill feed at reduced speed, is depressed.

The relay III is excited through the circuit L C, 51, 5 G, L and maintained excited through the circuit L D, c, 6, 4 F 51, 5 G, L The relay III closes its contacts 3 3 3 and the motor M starts up at reduced speed.

Simultaneously, supply of current to the relay VIII is stopped by the opening of the contact 3 which results in the excitation of the relay VI owing to the closure of the contact 8*; this ensures maintenance of the excitation of the relay III through the circuit: L D, c, 6 (closed by the excitation of the relay VI), 4 F 51, 5 G, L

It should be noted that there will be no trouble if, having pushed button B (operation 1) thereby starting the motor M one fails to push button C (operation 2). In fact, either of two cases will occur:

Either the reversible mechanical system (screw 26, auxiliary motor M is free; in this case, the nut 27 drives the screw 26 at its own speed, and since there is no relative screw-nut speed, the drilling motor M does not move; or, in a more frequently occurring case, the screw 26 remains immobilized by friction; in this case, the nut is unscrewed from the screw, the drilling aggregate (M 27, 20) moves back, and stopping would be effected by the opening of switch H corresponding to the end of rearward travel if the operation has not acted in the meantime.

(3) The push button F corresponding to a more rapid feed of the drill-bit is depressed and this closes the contact F and opens the contact F This results in:

(A) either normal operation of the machine with the high speed drill feed. The relay II is still excited by its maintenance circuit. The relay III is no longer excited owing to opening of the contact F The relay IV is excited through its circuit L F 3 52, 5 G, L which closes in particular the contacts 4*, 4 4 supplying cur rent to the

windings

44, 45, 46 of the motor M The relay VII is put in action by closure of the contact 3 which prepares the automatic operation by opening the contact or sign and the drill-bit moves rearwardly at high speed z-l- 1) XP- (5) The feed stopping contactor D is depressed and all the relays except the relay II are excited. The main motor M is the only one that rotates.

(6) The stop contactor A is depressed and all the relays cease to be excited. The two motors M and M are stopped.

Briefly, the start of the drilling operation is obtained by depressing the contactor B, depressing the contactor C results in reduced speed drill feed and then in depressing the faster contactor F normal speed is obtained at the same time as the short-circuit 7 of the operating coil of the relay I is broken, which permits this apparatus to operate when the maximum operational intensity is reached so as to automatically cause the drill feed to resume its reduced speed. It will be understood that it is then possible to return to normal operation by once more depressing the contactor F. If the consumed current intensity remains less than the pre-determined intensity, this speed is maintained; otherwise, the machine returns to the reduced speed position.

The end of travel switches G and H perform their normal functions at the end of the forward drill feed and at the end of the drill return movement by opening the relay circuit s.

The following table shows the various positions of the relays according to the contactor depressed. The letter X indicates an operative relay.

Oontactors Reference Characteristics Stoppage of drilling. Start of drilling.

Automatic operation ormal operation and preparation of automatic operation.

when maximum current intensity is reached. Return to reduced speed feed as obtained by depressing contractor O.

7 which excites the relay 1. The relay VIII is once more put into action through the circuit L A, b, F, a, 1 3, 56, 5 G, L The relay VI ceases to be excited owing to the opening of the contact 8 The relay IV is maintained excited, when the contact F is no longer depressed, by its maintenance circuit L D, c, 4 6 3 52, 5 G, L

(B) or an automatic return to the low speed drill feed if the load on the motor M reaches a given maximum. At this moment, the relay I operates and opens the contact 1 The relay VIII ceases to be excited. The relay V1 is put back into action by closure of the contact 8 The relay IV corresponding to high speed drill feed ceases to be excited owing to opening of the contact 6. The relay III corresponding to the low speed drill feed is put back into action by closure of the contacts 6 and 4 and then is once again supplied with current through its maintenance circuit. The drilling operation proceeds at low speed drill feed.

(4) The reverse drill travel contactor E is depressed. The motor M continues to rotate since the relay II is still excited.

The relay V is excited through the circuit E, e, 3, 4 53, H, L and it closes the contacts 5, 5 5, which permit the motor M to rotate at high speed but in the direction opposite to that corresponding to drilling.

Maintenance of the circuit current is ensured by closure of the contact 5 The speed M changes the direction Although a specific embodiment of the invention has been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claim.

Thus, the auxiliary motor M could have more than two windings, in which case there would be more than two ranges of variable speed drill feeds.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

A variable feed drill comprising a drilling tool, a longitudinally movable drilling tool carrier, a three-phase main motor coupled to and rotating said tool, a threaded member, a nut member engaging the threaded member, one of said members being longitudinally fixed, the other of said members being coupled to said carrier for moving the same, said three-phase motor rotating said other member, an auxiliary reversible motor rotating said one member whereby said carrier is moved in accordance with the difference between motor speeds, the auxiliary motor being a three-phase motor comprising at least two field windings including a different number of poles so that said auxiliary motor has at least two speed ranges each corresponding to one of said windings, the auxiliary motor having a greater slip than the first said motor and having a plurality of speed ranges, a control device independent of and coupled to the auxiliary motor for commutating the field windings thereof thereby automatically changing the range in accordance with the type of substance to be drilled, said control device comprising an electro-mechanical control including manually operated contactors, said control being coupled to said motors for a manual control of the movement of the carrier and of the speed range of the auxiliary 5 motor, an over-current relay disposed in the current supply of the first said motor, and circuits coupled to the auxiliary motor and relay, said relay actuating the winding of the auxiliary motor having the larger number of poles when current in the first said motor achieves a pre- 10 determined level.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS France Dec. 30, 1953