DESC:HEAVY DUTY TAPPING MACHINE

Field of the invention

The present invention generally relates to mechanical engineering and more particularly, to a heavy-duty tapping machine.

Background of the invention

A traditional screw threading process includes fixing a work piece into a fixture and starts tapping with a knife. The method can work on a single piece at a time, and tapping procedures starts after waiting for a hole to be drilled thereon. This reduces speed of operation and efficiency of the process. In addition to this, in manual operation, chances of breaking of the thread are high, and make this higher cost of production. Therefore, it is necessary to adopt automation in the field of tapping that would increase the accuracy, operating efficiency of the technicians, and reduced processing cost.

A heavy-duty tapping machine disclosed in CN202461721U used for batch processing of work pieces comprises a rack and a tapping machine case. The tapping machine case is arranged in the rack that is movable in an up and down directions. The tapping machine case comprises a casing, a machine core and a tapping motor. The machine core comprises a tapping transmission mechanism connected to an output shaft of the tapping motor, a rotary shaft extending downwards, an upper component table and a lower component table which are fixed on the rotary shaft, an upper sleeve matched with the upper component table in a joint mode, and a lower sleeve matched with the lower component table in a joint mode. The upper sleeve and the lower sleeve are driven by the tapping motor through the tapping transmission mechanism and are capable of rotating in opposite directions. Also, upper sleeve and the lower sleeve move in up and down in a linkage mode. The machine provides an automated production of a plurality of work piece continuously; yet, the machine is unable to perform the tapping operation of size M36 to M80 in a single pass.

Further, the conventional tapping machines have low production rate hence, unsuitable for mass production and the surface finish offered may not be satisfactory.

Accordingly, there exists a need to provide a heavy-duty tapping machine that overcomes the drawbacks of the conventional techniques.

Objects of the invention

An object of the present invention is to achieve a tapping operation of job size M36 mm to M80 mm in a single pass.

Another object of the present invention is to increase the productivity of tapping up to size M80X6 mm pitch in a single pass.

Yet another object of the present invention is to automate the tapping operation and obtain high production rate.

Yet another object of the present invention is to automate the process of tapping and produce a plurality of work pieces simultaneously.

Summary of the invention

Accordingly, the present invention provides a heavy duty tapping machine (hereinafter, “the machine”). The machine comprises a component loading assembly, a component unloading assembly, a torque generating unit, a spindle assembly, a vertical slide assembly, a vertical slide synchronization assembly, a controller, a variable frequency drive unit (hereinafter, “VFD unit”), a pneumatic system and a coolant flow system. The component loading assembly includes spacer plates for placing jobs to be tapped thereon, and V-guide pushers positioned on the spacer plates and fixed on shafts of pusher cylinders. Each pusher cylinder is provided with two sensors to sense forward and reverse positions of pistons.

The spindle assembly includes a tap holder having a tap fitted therein, a spindle, and a gear mounted on the spindle. The tap rotates in synchronization with the spindle in anyone of a clockwise direction and an anti-clockwise direction. The torque generating unit includes an electric motor connected to a gear box and a ball screw assembly. The gear box is a heavy duty gear box that provides maximum torque at low rpm for higher size tapping. The ball screw assembly includes a ball screw that rotates through a spur gear connected to the spindle gear. Specifically, the spindle assembly is connected with a gear and a pinion, and is driven by the electric motor through the gear box. The vertical slide assembly is capable of moving in an upward direction and a downward direction through the ball screw. The vertical slide synchronization assembly includes two toothed wheels mounted on the ball screws. The toothed wheels rotate with the ball screws and each toothed wheel is provided with a proximity switch to sense rotation thereof. The vertical synchronization assembly in connection with the vertical slide assembly balances the vertical movements.

The component unloading assembly includes a conveyor belt and an automatic pneumatic pusher for pushing a finished job to the conveyor belt for unloading. The controller includes a processing unit, a memory unit and a plurality of interfacing circuits. The controller is operably connected to the component loading assembly, the component unloading assembly and the VFD unit. The controller produces command to rotate the spindle. The VFD unit couples the controller with the electric motor and controls motor speed in accordance with the commands received from the controller as per speed requirements. The controller is further connected to a human machine interface unit, and a feedback target wheel assembly that includes a proxy cam assembly to control the vertical slide movements of the job during any failure of tapping and stop the entire operation. The coolant flow system provides lubrication to cutting tool and carries away the cutting heat and chips. The pneumatic system includes a filter, regulator and lubricator unit positioned at a rear side of the machine.

In accordance with the present invention, the V-guide pushers and the pusher cylinders push the job under the spindles that starts rotation according to the selected speed by the variable frequency drive unit causing the rotation of the tap in the clockwise direction for tapping operation and when the vertical slide assembly reaches an upper limit, the controller produces command to rotate the spindle thereby causing the tap to rotate in the anti-clock wise direction and simultaneous movement of the vertical slide assembly in the downward direction till reaching a lower limit thereafter the auto pusher pushes the job towards the conveyor belt to unload a finished job to a storage bin. The machine performs tapping operation of the job size M36 mm to M80 mm in a single pass.

Brief description of the drawings

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1A shows a perspective view of a heavy-duty tapping machine, in accordance with the present invention;

Figure 1B shows another perspective view of the heavy-duty tapping machine from rear side, in accordance with the present invention;

Figure 2A shows a front view of the heavy-duty tapping machine, in accordance with the present invention;

Figure 2B shows a left side view of the heavy-duty tapping machine, in accordance with the present invention;

Figure 2C shows a right side view of the heavy-duty tapping machine, in accordance with the present invention;

Figure 2D shows a top view of the heavy-duty tapping machine, in accordance with the present invention;

Figures 3A - 3B show a component loading assembly of the heavy-duty tapping machine, in accordance with the present invention;

Figure 4 shows a spindle drive unit of the heavy-duty tapping machine, in accordance with the present invention; and

Figure 5 shows a spindle assembly of the heavy-duty tapping machine, in accordance with the present invention.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides a heavy-duty tapping machine that is capable of performing automated tapping operation of job size M36 to M80 in a single pass. The machine includes a vertical multi-head that improves the production rate and provides a better surface finish.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in brackets in the following description.

Referring to figures 1 to 5, a heavy-duty tapping machine (100) (hereinafter, ‘the machine (100)’) in accordance with the present invention is shown. The machine (100) supports multiple tap heads and gives an option to select the number of tap heads based on a user preference. Particularly, the machine (100) supports up to four tap heads and is capable of tapping job size M36 mm to M80 mm in a single pass, more specifically of M80X6 mm pitch and for M36X4 mm pitch. In the context of the present invention, two station machine having two spindles for carrying out thread cutting of two jobs simultaneously is shown. However, it is understood that the description of the two station machine is to be interpreted merely as an illustration of the concept of the present invention and it is in no way to be construed as a limitation.

The machine (100) comprises a component loading assembly (10), a component unloading assembly (not shown), a torque generating unit, a spindle assembly (30), a vertical slide assembly (40), a vertical slide synchronization assembly (50), a controller (not shown), a variable frequency drive unit (hereinafter, “VFD unit”), a pneumatic system (not shown) and a coolant flow system (not shown). All the components of the machine (100) are operably connected to each other.

As shown in figures 3A-3B, the component loading assembly (10) includes spacer plates (2), V-guide pushers (4) and pusher cylinders (6). The jobs to be tapped are placed on the spacer plates (2) by an operator. The V-guide pushers (4) are positioned on the spacer plates (2) and fixed on shafts of the pusher cylinders (6). The V-guide pushers (4) are selected as per the size of the job for example, hex nut. The pusher cylinders (6) are mounted through brackets (8) and screws. The pusher cylinders (6) preferably pneumatic cylinders, and the V-guide pushers (4) push the job forward under spindles (22). In an embodiment, the component loading assembly (10) is an automatic assembly. Each pusher cylinder (6) is provided with two sensors to sense forward and reverse positions of pistons and is used as interlock signals for continuation of a cutting cycle. The component unloading assembly includes a conveyor belt (not shown) and an automatic pneumatic pusher (not shown). The automatic pneumatic pusher pushes the finished job to the conveyor belt so as to unload the finished job or component and other parts to a storage bin.

The torque generating unit comprises an electric motor (12) connected to a gear box (14) and a ball screw assembly (16). The electric motor (12), preferably an induction motor, is connected to the gear box (14) through a motor shaft, a gear box shaft and coupling means. The gear box shaft is connected to a pinion through a first coupling means at one end and the electric motor (12) at the other end. The pinion is further coupled to the spindle assembly (30), wherein a spindle gear (24) receives the pinion such that the spindle (22) rotates through the gear box (12). Thus, the spindle assembly (30) is connected with the gear and the pinion, and is driven by the electric motor (12) through the gear box (14).

The spindle assembly (30) includes a tap holder, the spindle (22) and the gear (24) mounted on the spindle (22). The tap holder is inserted into the spindle (22) such as to match a spindle hole and a tap holder hole and fitted therein through a locking screw provided on the spindle (22). The tap holder includes a tap fitted therein such that the tap rotates in synchronization with the spindle (22) in anyone of a clockwise direction and an anti-clockwise direction. Specifically, the tap holder holds the tap through a grub screw. The tap holder can be changed based on tapping size and holding diameter of the tap.

The gear box (14) is mounted on a spindle drive unit (18) through a spacer (20). In the context of the present invention, a spindle kinematic train consists of the electric motor (12), reduction gear box (14) and 1:2 reduction gearing between reduction gear box output gear and the spindle mounted driven gears (24). The gear box (14) is a heavy duty gear box that provides sufficient high torque for higher size tapping. The gear box (14) is designed in such a way to provide maximum torque at low RPM for higher size tapping. The gear box (14) is further associated with the ball screw assembly (16) and thereby the motor arrangement offers higher accuracy of tapping operation.

The ball screw assembly (16) comprises a ball screw (not shown) that rotates through a spur gear (not shown) which is connected to the spindle gear (24). The vertical slide assembly (40) is capable of moving in an upward direction and a downward direction through the ball screw. A gear train between the spindle (22) and the vertical slide assembly (40) is set in such manner that for one rotation of the spindle (22), the vertical slide assembly (40) carrying the job moves up by one pitch distance. Specifically, the vertical slide assembly (40) is affected by the two ball screws and nuts on either side thereof moving in synchronization with the spindles (22). The vertical slide synchronization assembly (50) is attached at a bottom end of both the vertical ball screws. The vertical slide synchronization assembly (50) includes two toothed wheels mounted on the ball screws. The toothed wheels rotate with the ball screws. Each toothed wheel is provided with a proximity switch to sense rotation thereof. Any lag or stoppage of one ball screw is sensed by proximity switch signal lag/ stoppage. This indicates loss of synchronization and results into stoppage of the machine (100).

The controller is operably connected to the component loading assembly (10), the component unloading assembly and the VFD unit. The VFD unit couples the controller with the electric motor (12). The VFD controls motor speed in accordance with the commands received from the controller as per speed requirements. In the context of the present invention, the controller is an assembly of processing unit in association with a memory unit and a plurality of interfacing circuits in compatible with a plurality of components connected thereto. The memory unit is configured with an application module having a set of instructions stored therein. The application module is capable of producing commands necessary for controlling the operations of the components connected thereto.

The controller is further connected to a human machine interface unit (not shown) and a feedback target wheel assembly (60). In an embodiment, the human machine interface unit (hereinafter, “HMI unit”) includes a visual display unit that displays the operations of the controller. Specifically, the controller is a programmable logic controller (PLC) that allows the HMI unit to communicate with a user by means of the VDU preferably, a touch screen. The feedback target wheel assembly (60) is electrically coupled to the controller. The feedback target wheel assembly (60) includes a proxy cam assembly (52) which controls the vertical slide movements of the job during any failure of tapping and is capable of stopping the entire operation.

The machine (100) is equipped with the coolant flow system to provide lubrication to cutting tool and to carry away the cutting heat and chips. A trough at bottom end of column of the machine (100) acts as a coolant tank for cutting fluid. Oil, along with chips from machining area, falls down through a central funnel on to a magnetic chip conveyor which is inserted in the column window. The magnetic chip conveyor carries the chips to outside into a chip collection trolley. The cutting oil gets collected into stage wise filtration compartments at the bottom of the column. The filtered cutting oil is again pushed to the cutting tools through a solenoid valve and flexible nozzles. The solenoid is switched ON by cutting cycle start push button.

The pneumatic system includes a filter, regulator and lubricator unit (hereinafter, “FRL unit”) positioned at a rear side of the machine (100). An inlet of the FRL unit has a T connection which is brought to job output connected to the FRL unit and to a ball valve. The outlet of the ball valve is connected to flexible conduits and then to nozzles which blow the oil from machined jobs coming out from an outlet chute of a column. The FRL unit is further connected to a pressure switch which confirms availability of pressurized air for the pusher cylinders (6) and supply is further connected to 2/5 pneumatic solenoid valve.

Referring again to figures 1-5, in an operation, the job preferably a hex nut is manually placed on the spacer plates (2) in front of the V-guide pushers (4). Upon pressing a start button, the V-guide pushers (4) and the pusher cylinders (6) push the job under the spindles (22). The spindles (22) start rotation by the VFD unit according to the selected speed. The tap rotates in the clockwise direction in the spindle (22) for tapping operation and accordingly, the vertical slide assembly (40) moves in the upward direction. Specifically, the vertical slide assembly (40) moves up towards the tap by means of the ball screw nut attached to the vertical slide in a locked relation of one pitch per one spindle rotation. The end of forward (upward) stroke is sensed by the proximity switch and the spindle (22) starts reverse rotation causing the retraction of the vertical slide assembly (40) to bring the job to a starting position. The spindle (22) and the vertical slide assembly (40) stop rotating once the end position is sensed by the proximity switch thereby stopping the main drive. The vertical synchronization assembly (50) in connection with the vertical slide assembly (40) balances the vertical movements. When the vertical slide assembly (40) reaches the upper limit, the controller produces command to rotate the spindle (22) thereby causing the tap to rotate in the anti-clock wise direction. Simultaneously, the vertical slide assembly (40) moves in the downward direction. The upper limit and the lower limit of the vertical movements are sensed by the proximity switches that are coupled to the controller. The operator has to load the next job in in front of the V-guide pushers (4). As the pusher cylinders pushes the next job to cutting position under the spindle (22), the auto pusher pushes the earlier job through a column chute towards the conveyor belt to unload the finished job to the storage bin.

In accordance with the present invention, the machine (100), in compliance with the instructions stored in the controller, provides four modes of operation namely: a setting mode, a manual mode, a semi-automatic mode and a fully automatic mode.

In the setting mode in accordance with the present invention, the upper and the lower limit of the vertical slide assembly (40) is set through buttons. Further, in this mode RPM of the spindle (22) is fixed.

In the manual mode in accordance with the present invention, on pressing the start button, the vertical slide moves in the upward direction up to the upper limit and then moves down in a reverse direction of the spindle (22) and comes down up to the lower limit of the proximity switch as per stroke set and stops the machine (100). The checking of the setting on job i.e. hex nut tapping and making corrections accordingly if required is done manually. In this mode, the pusher cylinders (6) do not work.

In the semi-automatic mode in accordance with the present invention, on pressing the start button, the auto pusher pushes the job towards the spindle (22) and returns back to a home position. The vertical slide moves in the upward direction causing the spindle (22) to rotate in the clock-wise direction as per rpm set in the HMI unit. Once the upper sensor is activated, the spindle (22) rotates in the anti-clockwise direction and the vertical slide moves down until the lower limit sensor is activated and thereafter, the spindle rotation stops once cycle is complete. In this mode, after completing one cycle, the machine (100) stops and the operator needs to again press the cycle start button to start a new cycle and then the cycle is repeated as mentioned above. The setting of the machine (100) for required tapping size is done manually. This consists of engaging the tap in the spindle (22), setting a feed gear train on gear quadrant arm for required pitch, setting job loading station under the spindle (22) by mounting axial and side spacers and setting cams of the proximity switches for end position of threading length.

In the fully automatic mode in accordance with the present invention, on pressing the cycle start button, the machine (100) runs automatically as per setting parameter set. The machine (100) continues in running mode till the cycle stop button is pressed. In case of an abnormal position, an emergency stop button can be pressed to stop the machine (100) immediately.

Advantages of the invention

1. The machine (100) offers high production rate hence, the cost per component is very low.
2. The machine (100) is designed in such a way to achieve max torque at low rpm for tapping of M80X6 mm pitch and for M36X4 mm pitch. Thus, the machine (100) provides torque at high rpm through the reduced gear box (14) and the electric motor (12).
3. In the machine (100), one tapping machine can replace three CNC turning centre. For thread cutting of M48X5 mm Hex Nut by using a CNC turning machine, the cycle time is 90 sec. per piece. Whereas, for the same operation, the heavy-duty tapping machine (100) takes 30 sec. per piece. Hence, the output rate on the machine (100) is 980 numbers when the output rate of CNC turning center is 252 numbers.
4. The machine (100) is suitable for tapping up to M80X6 mm pitch in a single pass which is not possible with an ordinary tapping machine.
5. The automatic material feeding unit and the automatic material unloading unit makes the machine (100) completely automated tapping machine.
6. The variable frequency drive unit of the machine (100) offers various cutting speeds for speed of operation.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention. ,CLAIMS:We claim:

1. A heavy duty tapping machine (100) comprising:
a component loading assembly (10) having spacer plates (2) for placing jobs to be tapped thereon, and V-guide pushers (4) positioned on the spacer plates (2) and fixed on shafts of pusher cylinders (6), each pusher cylinder (6) being provided with two sensors to sense forward and reverse positions of pistons;
a spindle assembly (30) having a tap holder having a tap fitted therein, a spindle (22), and a gear (24) mounted on the spindle (22), the tap rotates in synchronization with the spindle (22) in anyone of a clockwise direction and an anti-clockwise direction;
a torque generating unit having an electric motor (12) connected to a gear box (14) and a ball screw assembly (16), the ball screw assembly (16) having a ball screw that rotates through a spur gear connected to the spindle gear (24);
a vertical slide assembly (40) being capable of moving in an upward direction and a downward direction through the ball screw;
a vertical slide synchronization assembly (50) having two toothed wheels mounted on the ball screws, the toothed wheels rotate with the ball screws, each toothed wheel being provided with a proximity switch to sense rotation thereof;
a component unloading assembly having a conveyor belt and an automatic pneumatic pusher for pushing a finished job to the conveyor belt for unloading;
a controller having a processing unit, a memory unit and a plurality of interfacing circuits, the controller operably connected to the component loading assembly (10), the component unloading assembly and a variable frequency drive unit, the controller produces command to rotate the spindle (22);
a coolant flow system to provide lubrication to cutting tool and to carry away the cutting heat and chips; and
a pneumatic system having a filter, regulator and lubricator unit positioned at a rear side thereof,
wherein, the V-guide pushers (4) and the pusher cylinders (6) push the job under the spindles (22) that starts rotation according to the selected speed by the variable frequency drive unit causing the rotation of the tap in the clockwise direction for tapping operation and when the vertical slide assembly (40) reaches an upper limit, the controller produces command to rotate the spindle (22) thereby causing the tap to rotate in the anti-clock wise direction and simultaneous movement of the vertical slide assembly (40) in the downward direction till reaching a lower limit thereafter the auto pusher pushes the job towards the conveyor belt to unload the finished job to a storage bin.

2. The heavy duty tapping machine (100) as claimed in claim 1, wherein the variable frequency drive unit couples the controller with the electric motor (12) and controls motor speed in accordance with the commands received from the controller as per speed requirements.

3. The heavy duty tapping machine (100) as claimed in claim 1, wherein the spindle assembly (30) is connected with a gear and a pinion, and is driven by the electric motor (12) through the gear box (14).

4. The heavy duty tapping machine (100) as claimed in claim 1, wherein the gear box (14) is a heavy duty gear box that provides maximum torque at low rpm for higher size tapping.

5. The heavy duty tapping machine (100) as claimed in claim 1, wherein the controller is further connected to a human machine interface unit, and a feedback target wheel assembly (60) that includes a proxy cam assembly (52) to control the vertical slide movements of the job during any failure of tapping and stop the entire operation.

6. The heavy duty tapping machine (100) as claimed in claim 1 performs tapping operation of job size M36 mm to M80 mm in a single pass.

7. The heavy duty tapping machine (100) as claimed in claim 1, wherein the vertical synchronization assembly (50) in connection with the vertical slide assembly (40) balances the vertical movements.