JPH11254211A - Turret tool rest device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fixedly maintain a turret in dividing position on a support structure and to make a detach drive mechanism for releasing the fixation electric- powered without adding a new electric motor. SOLUTION: The turret tool rest device is provided with a ring-shaped fixed coupling element 56 fixed on a supporting structure 20, a ring-shaped movable coupling element 58 fixed on a turret 24, and a direct acting sleeve 54 for moving the ring-shaped movable coupling element 58 between the engaging position and the disengaging position with respect to the ring-shaped fixed coupling element 56, as a locking means to check the rotation of the turret 24 after swirl division. The direct acting sleeve 54 makes an axial movement by the drive of a servo motor 74 connected to the direct acting sleeve 54 through a lever 72 and moves the turret 24 in the axial direction. The turret 24 is connected to a servo motor 40 for rotational tools through a cylinder clutch member 50 and a clutch gear 76 and makes swirl division by the servo motor 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary tool rest device installed on a machine tool such as a lathe, and more particularly, to a tool fixedly held at an indexing position by a turning indexing operation of the tool post. To this end, the present invention relates to a turret tool rest device provided with a locking means for preventing rotation of the tool rest after rotation indexing.

[0002]

2. Description of the Related Art In a machine tool such as a lathe, a large number of tools are carried in advance and a desired tool is selected by a turning indexing operation in order to promote automation and speeding up of a machining operation. 2. Description of the Related Art A rotary tool rest structure for positioning at a working position, that is, a tool equipped with a turret tool rest apparatus is well known. For example, a turret tool rest device used in an automatic turning machine such as an NC lathe generally includes a tool feeder installed on a machine base opposite to a rotating spindle, and a tool feeder along a given coordinate axis. And a turret rotatably supported by the support and supporting a number of tools at predetermined intervals around a rotation axis.

In this type of turret tool rest device, it is necessary to firmly fix the turret on the support table after the turret is rotated and indexed and then the workpiece is machined by the selected tool. To that end, turret tool rest devices generally comprise locking means for locking the turret at each of a plurality of indexing positions on the support. Conventionally, this locking means has a pair of engaging members provided on each of the turret and the support base, which can be engaged with each other, and a mechanism for relatively moving the engaging members between an engaging position and a disengaging position. And a de-drive mechanism. As the engaging member, a mutually-removable coupling having a meshing clutch-like structure is generally used. In this case, the engagement / disengagement drive mechanism is configured to move the engaging member on the turret side relative to the engaging member on the support base in the axial direction.

[0004] As a tool selection procedure, first, at the stage when the work processing by one tool is completed, the support base is moved on the tool feed base together with the turret, and the tool is sent from the processing work position to the tool change position. Next, the turret-side engaging member is moved by the driving of the engagement / disengagement driving mechanism to disengage from the support base-side engaging member, and in that state, the turret is rotated by another rotary drive source to perform turning indexing, Select the desired tool.
Next, the turret-side engagement member is engaged with the support base-side engagement member by driving the engagement / disengagement drive mechanism, and the selected tool is fixedly held at the indexing position. In this state, the support table is moved together with the turret on the tool feed table, and the selected tool is sent from the tool change position to the machining operation position.

[0005]

An automatic turning machine such as an NC lathe includes a rotary drive source for a spindle, a drive source for each axis for tool feed,
A plurality of drive sources having different control targets, such as a chuck open / close drive source, are provided. Servo motors are generally used for these drive sources, particularly in parts (spindle, tool feed, etc.) where high-speed and high-precision response is required. Furthermore, in recent years, the opening / closing drive source of the chuck and the portion where a hydraulic or pneumatic actuator is conventionally used, such as the turret rotation drive source of the turret tool post device, are advantageous in terms of environmental hygiene and operation reliability. Servo motors tend to be used.

However, in the above-described engagement and disengagement drive mechanism of the turret tool rest device, the required operation is a simple operation of only slightly moving one of the engagement members in the axial direction. Electrification has been delayed, and many still employ hydraulic or pneumatic actuators. The hydraulic / pneumatic actuator generally has problems such as deterioration of the working environment due to noise and air pollution, increase in equipment cost, enlargement of the machine, and low response accuracy. In particular, when a hydraulic cylinder is used as the engagement / disengagement drive source, the operating speed easily changes due to a change in the temperature of the hydraulic oil. Not only is it difficult to stably control the operation, but also the hydraulic cylinder itself is a considerable heat source, which may affect the operation of the surrounding mechanical components. Therefore, it is desired that the engagement / disengagement drive mechanism of the turret tool rest device is also electrically operated.

On the other hand, the turret tool rest apparatus in which the drive source is motorized has a configuration in which a servomotor as a turret rotation drive source is installed on a support base and can carry not only fixed tools such as cutting tools but also rotary tools such as drills. In this case, the servomotor for the rotary tool is also installed on the support base. And, in order to respond to the demand for the electrification of the engagement / disengagement drive mechanism, when a servomotor as an engagement / disengagement drive source is further installed on a support base, a moving element along a given coordinate axis on a turning machine is required. Unnecessarily increase the weight of one support base,
Not only does the response accuracy deteriorate, but also the problems such as an increase in the size of the entire machine and an increase in manufacturing and operating costs occur.

Accordingly, an object of the present invention is to make an engagement / disengagement drive mechanism for holding and releasing a turret fixedly at an indexing position on a support base electric without adding a new electric motor, As a result, a turret tool rest device that can reduce noise and air pollution, improve response accuracy, reduce manufacturing and operation costs, and promote the further miniaturization and higher performance of mounted machine tools. To provide.

[0009]

In order to achieve the above object, according to the present invention, there is provided a support table movably mounted on a machine tool along a given coordinate axis, A turret that is rotatably supported on the turret and carries a number of tools at predetermined intervals around a rotation axis; locking means for fixedly holding the turret with respect to the support at a rotation indexing position on the support; In a turret tool rest apparatus provided with a first electric motor for driving a rotary tool carried on a turret, a locking means is provided on a fixed side engaging element provided on a support base and on a turret. The movable side engaging element, the engaging position where the movable side engaging element is engaged with the fixed side engaging element to prevent the turret from rotating, and the turret can be rotated by separating from the fixed side engaging element. And a drive mechanism to move the A drive mechanism comprising: a lever fixedly connected in the axial direction to the turret; and a second electric motor for moving the turret in the axial direction by swinging the lever, and the turret shaft driven by the second electric motor. A clutch means for operatively connecting or disconnecting the first electric motor to or from the turret in conjunction with the directional movement, wherein the first electric motor rotates the turret when the movable-side engaging element is in the disengaged position; A turret tool rest device is provided which performs turning indexing.

According to a second aspect of the present invention, in the turret tool rest apparatus according to the first aspect, the clutch means is axially fixed to the support table so as to be rotatable and is rotatably supported by the turret. A cylindrical clutch member fixedly and axially movable; and a clutch gear fixed to the turret in the axial direction and rotatably connected to the cylindrical clutch member, wherein the clutch gear is the first clutch gear. And a turret tool rest device connected to a second electric motor.

According to a third aspect of the present invention, in the turret tool rest apparatus of the first or second aspect, a rotary tool is mounted on a front end side surface of the turret, and the first electric motor penetrates the turret in the axial direction. The present invention provides a turret tool rest device for driving a rotary tool via a driving shaft to be driven and a driving gear concentrically fixed to the driving shaft and housed at a front end of the turret.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals. Referring to FIG. 1, a turret tool rest apparatus 10 according to one embodiment of the present invention is shown mounted on an automatic turning machine such as an NC lathe. Turret tool post device 10
Is arranged to face the rotary spindle 12 of the automatic turning machine. The rotary spindle 12 is mounted and housed in a housing-shaped headstock 14, grips a bar W to be turned, and is rotationally driven by a drive source (not shown). The turret tool rest device 10 carries a large number of tools required for machining the bar W in a predetermined position in advance, selects a desired tool according to a machining location of the bar W by a turning indexing operation, and performs automatic turning. It is positioned at the machining operation position at the tip of the rotary spindle 12 of the machine.

The turret tool rest apparatus 10 includes a rotating spindle 12.
A tool feed base 18 installed on the machine base 16 of the automatic turning machine in opposition to the above, a support base 20 movably installed on the tool feed base 18 along a given coordinate axis, and a support base 20. A turret 24 rotatably supported and carrying a number of tools 22 at predetermined intervals around a rotation axis. In the illustrated embodiment, the tool feed base 18 is moved in the Z-axis direction substantially parallel to the center axis of the rotary spindle 12 by driving a Z-axis feed motor (not shown), and the support base 20 is moved to the center axis of the rotary spindle 12. The turret 24 is configured to move in a substantially orthogonal X-axis direction by driving an X-axis feed motor (not shown).
The various tools 22 selected above turn the bar W into a desired shape under the double-axis feed operation.

FIGS. 2 and 3 show the structure of the turret 24 supported on the support base 20 in detail. The turret 24 includes a hollow head 26 having a cylindrical or prismatic outer shape and a head 2.
6 and a hollow cylindrical shaft portion 28 extending concentrically in the axial direction from one axial end surface. Turret 24 head 26
Are arranged so as to protrude outward from a front end surface (right end in the figure) of the support base 20, and a plurality of tool mounting portions 30 for mounting the tools 22 are provided on the radially outer peripheral surface at predetermined index angles. Can be The tool mounting portion 30 includes a fixed tool mounting portion 30a for removably mounting a fixed tool 22a such as a cutting tool via a holder 32 as shown in the figure, and a rotating tool 22b such as a drill for mounting and dismounting via a holder 34. And a rotary tool mounting portion 30b for mounting as possible. Further, the rotary tool mounting portion 30b is formed at two locations separated from each other in the axial direction at one indexing angle position.

The rotary tool 22b includes a head 26 and a shaft 28
The drive is generally driven by a servomotor 40 installed at the rear end (the left end in the figure) of the support base 20 via a drive shaft 36 and a drive gear 38 installed inside. The drive shaft 36 is
The turret 24 is rotatably supported on the shaft 28 by a plurality of bearings. The drive shaft 36 is connected at its rear end 36a to the output shaft of the servomotor 40 via gears 42 and 44. In the figure, the shaft of the gear 44 is shown separated from the drive shaft 36 to clearly show the gear train, but in actuality, both shafts are arranged closer to each other and fixed to the rear end 36a of the drive shaft 36. A gear 44 is directly meshed with the gear 42. The two drive gears 38 are concentrically fixed near the front end 36b of the drive shaft 36, corresponding to the position of the rotary tool mounting portion 30b provided on the head 26 of the turret 24. Each drive gear 38 has a beveled tooth on the outer periphery, and operatively meshes with a bevel gear 46 provided at the rear end of the rotary tool 22b mounted on the rotary tool mounting portion 30b.

The drive shaft 36 is driven by the drive of the servomotor 40.
Is rotated, the two drive gears 38 rotate simultaneously, and can drive the rotary tool 22b mounted on the desired rotary tool mounting portion 30b. Since the turret 24 has such a configuration, the rotary tool mounting portion 30b can be easily added to a desired index angle position and an axial position of the head 26.

The shaft 28 of the turret 24 is rotatably and axially received in a turret receiving cavity 48 of the support base 20. From the approximate center of the shaft 28 to the front (right side in the figure)
Is slidably supported by the cylindrical inner wall surface 48a defining the turret receiving cavity 48 of the support base 20 so as to prevent rattling in the radial direction. A rear end (left end in the drawing) region of the shaft portion 28 is received in a central hole 52 of a cylindrical clutch member 50 described later, and receives a linear motion sleeve 54 described later projecting in the axial direction from the rear end of the shaft portion 28. I do.

The turret tool rest device 10 includes an annular fixed coupling element 56 fixed to the support base 20 and an annular fixed fixed to the turret 24 as locking means for preventing unnecessary rotation of the turret 24 after the rotation indexing. An interlocking mechanism including the movable coupling element 58 and a drive mechanism (described later) for moving the annular movable coupling element 58 with respect to the annular fixed coupling element 56 between an engagement position and a disengagement position are provided. The annular fixed coupling element 56 has a meshing clutch-like structure and is fixed near the axially forward open end of the turret receiving cavity 48 of the support base 20.
The annular movable coupling element 58 likewise has an intermeshing clutch-like structure, the head 26 of the turret 24 and the shaft 28
Is fixed in the vicinity of the connection portion with

On the front end face (right end face in the figure) of the annular fixed coupling element 56, a large number of teeth 60 are provided radially at a predetermined pitch, and on the rear end face (left end face in the figure) of the annular movable coupling element 58. Has a number of teeth 62 that can mesh with the teeth 60
Are provided radially at a predetermined pitch. The annular fixed coupling element 56 and the annular movable coupling element 58 are arranged with their teeth 60, 62 axially facing so that they can engage and disengage from each other. When the turret 24 is not rotating, the annular movable coupling element 58 moves in the axial direction together with the turret 24, so that the coupling elements 56 and 58 are mutually engaged and disengaged. I have.

In the state shown in FIG. 2, the teeth 60 of the annular fixed coupling element 56 and the teeth 62 of the annular movable coupling element 58 are engaged with each other, and the annular movable coupling element with respect to the annular fixed coupling element 56 is engaged. 58 is prevented from rotating, so that the turret 2
4 is prevented from rotating. That is, in this state, the annular movable coupling element 58 is placed at the rearmost (left end in the figure) engagement position together with the turret 24 within its axial movement range.

While the turret 24 and the annular movable coupling element 58 are in the above-mentioned engaged positions, the bar 22 gripped by the rotary spindle 12 is processed by the tool 22 mounted on the head 26 of the turret 24. Is done. During this time, turret 2
4 is a tool 22 during machining by the mutual engagement mechanism described above.
Is firmly and fixedly held on the support base 20 with sufficient strength to withstand the stress applied to the substrate and to maintain the processing accuracy.

When the turret 24 and the annular movable coupling element 58 are moved forward (to the right in the drawing) from the engagement position shown in the drawing to the disengaged position, the annular movable coupling element 58
Of the annular stationary coupling element 56 are disengaged. As a result, the annular movable coupling element 58 can freely rotate with respect to the annular fixed coupling element 56,
Therefore, the fixing of the turret 24 to the support base 20 is released, and the turret 24 is placed in a state in which the turret 24 can be turned and indexed.

In the turret tool rest apparatus 10, the turret 2
A rotary drive source for turning index 4 uses a servo motor 40 that is a rotary tool drive source. Therefore, when the turret 24 is turned and indexed, the turret 2
4 and the servomotor 40 are operatively connected to each other,
When driving 2b, it is necessary to interrupt the operative connection between the turret 24 and the servomotor 40. In the present embodiment, such switching of the drive target is performed by the operation of the cylindrical clutch member 50 and the linear motion sleeve 54 described above.

The cylindrical clutch member 50 is a hollow cylindrical member having a large number of clutch teeth 64 projecting radially from a rear end face (left end face in the figure), and is rotatable on the support base 20 via a bearing 66 and in an axial direction. It is immovably supported. The cylindrical clutch member 50 is connected to the outer peripheral surface of the rear end of the shaft portion 28 of the turret 24 by a key 68 so as to be non-rotatable and axially movable. Therefore, when the turret 24 rotates, the cylindrical clutch member 50 rotates together with the turret 24. When the turret 24 moves in the axial direction, the cylindrical clutch member 50 does not move, and only the turret 24 moves in the axial direction.

The translation sleeve 54 is a hollow cylindrical member capable of receiving the drive shaft 36, and has a bearing 7 at a front end (right end in the figure).
The turret 24 is rotatably supported by the shaft portion 28 of the turret 24 via the shaft 0 so as not to move in the axial direction. The rear end (left end in the figure) of the linear motion sleeve 54 is installed at the rear end (left end in the figure) of the support table 20 via a lever 72 that is swingably attached to the support table 20 by a pivot 72a. Output shaft device 7 of servo motor 74
5 is connected. As clearly shown in FIG. 3, the output shaft device 75 includes a rotation nut 75b connected to a rotation shaft 74a of the servomotor 74 via a coupling structure 75a,
A direct-acting shaft 75c having an external thread (not shown) screwed into a female thread (not shown) provided on the inner peripheral surface of the rotating nut 75b; It is swingably attached to one end of the lever 72. In this way, the direct power converted from the rotational force of the servomotor 74 by the output shaft device 75 is further transmitted to the direct acting sleeve 54 via the lever 72, whereby the direct acting sleeve 54 is Move axially inside the. In addition,
Such a power transmission mechanism using a lever mechanism has advantages that the structure is simple, there are few failures, and maintenance is easy.

A clutch gear 76 is fixed to a central region of the linear motion sleeve 54. The clutch gear 76 is a hollow cylindrical member integrally having a gear portion at a rear end (left end in the figure) and is connected to the servomotor 40 via a gear train 78. Therefore, the linear motion sleeve 54 is
, And rotates in the turret receiving cavity 48.
On the front end face (right end face in the figure) of the clutch gear 76, clutch teeth 80 that can be engaged with the clutch teeth 64 of the cylindrical clutch member 50 are radially projected at substantially the same pitch as the clutch teeth 64.

Turret 24, ie, cylindrical clutch member 5
When the linear motion sleeve 54 is moved in the axial direction by the drive of the servomotor 74 in a state where the rotation of the linear motion sleeve 54 is
Clutch teeth 64 and clutch teeth 80 of clutch gear 76
Engage and disengage with each other. The servo motor 40
While the clutch gear 76 is engaged with the cylindrical clutch member 50, a rotational force is applied to the turret 24 via the gear train 78, the clutch gear 76, and the cylindrical clutch member 50.
Therefore, in the turret tool rest apparatus 10, the turret 24 performs the turning indexing operation by the drive of the servo motor 40, and the desired tool 2 mounted on the desired tool mounting section 30 is obtained.
Select 2.

In the turret tool rest apparatus 10, when the translation sleeve 54 moves in the axial direction by the drive of the servomotor 74, the turret 24 connected to the translation sleeve 54 via the bearing 70 so as to be immovable in the axial direction. It moves axially within the turret receiving cavity 48 with the moving sleeve 54. That is, the driving mechanism for moving the annular movable coupling element 58 between the engagement position and the disengagement position is the linear motion sleeve 5.
4. It comprises a lever 72 and a servomotor 74.
As described above, the axial movement of the linear motion sleeve 54 is performed by a coupling engagement / disengagement operation for holding the turret 24 fixedly to the support 20 and a clutch engagement / disengagement operation for switching the drive target of the servomotor 40. The two operations are performed in conjunction with each other.

Specifically, in the illustrated embodiment, while the annular movable coupling element 58 is in the engagement position at the rearmost end (left end in the figure) together with the turret 24, the clutch of the cylindrical clutch member 50 is engaged. Tooth 64 and translation sleeve 54
Are disengaged from the clutch teeth 80 of the clutch gear 76 (see FIGS. 2 and 3). And turret 2
When the fourth and annular movable coupling elements 58 move forward (to the right in the figure) and are in the disengaged position, the clutch teeth 64 of the cylindrical clutch member 50 and the clutch teeth 80 of the clutch gear 76 engage with each other. , A clutch gear 76 is operatively connected to the turret 24.

Thus, the turret tool rest apparatus 10
Then, while the turret 24 is fixedly held to the support base 20, the servomotor 40 is used only for driving the rotary tool 22b, which is an original function, and after the turret 24 is unlocked, Servo motor 40 is turret 2
4 is configured to be able to rotate to perform turning indexing. At this time, the size and position of the two clutch teeth 64 and 80 are set so that the clutch gear 76 is engaged with the cylindrical clutch member 50 at substantially the same time when the annular movable coupling element 58 is disengaged from the annular fixed coupling element 56. By setting the relationship, unnecessary free rotation of the turret 24 during the transition from the machining operation to the tool changing operation is prevented, and the operator may be injured by the tool 22 or the tool 22 and peripheral devices may be damaged. Advantageously, fear is avoided.

The servo motor 4 is connected to the clutch gear 76.
The gear train 78 for transmitting the driving force of 0
2b includes a gear 44 meshing with a gear 42 for transmitting a driving force. Therefore, the driving force of the servo motor 40 is simultaneously transmitted to both the rotary tool 22b and the clutch gear 76. Needless to say, the number of rotations and the direction of rotation of the servomotor 40 are appropriately changed between the time of the machining operation for driving the rotary tool 22b and the time of the rotation indexing for rotating the turret 24.

As described above, in the turret tool rest apparatus 10, the engagement / disengagement drive mechanism for fixedly holding and releasing the turret 24 at the indexing position on the support base 20 and the turret 24 in the axial direction are provided. Servo motor 74, lever 72 and translation sleeve 5 for moving to disengage the mutual engagement mechanism
4, and a cylindrical clutch member 50 and a clutch gear 76 that enable the servomotor 40 for driving the rotary tool to be used as a drive source for turning the turret 24 in conjunction with the axial movement of the turret 24. Adopted. Therefore, conventionally, for rotating tool drive and turret 24
One servo motor is used for the indexing of the rotation of the other, and as a result, another servo motor is used for the engagement / disengagement drive mechanism without adding a new servo motor. A motor can be used. In addition, in order to transmit the driving force of the servomotor 74 of the engagement / disengagement drive mechanism to the turret 24, a lever mechanism that has a simple structure, is less likely to malfunction, and is easy to maintain is adopted. Therefore, the turret tool rest apparatus 10
Has effects such as reduction of noise and air pollution, improvement of response accuracy, suppression of manufacturing and operation costs, and further promotes downsizing and higher performance of a mounted machine tool.

[0033]

As is apparent from the above description, according to the turret tool rest apparatus of the present invention, the engagement / disengagement drive for fixedly holding and releasing the turret at the indexing position on the support stand. The mechanism can be motorized without adding a new electric motor, and the driving force of the engagement / disengagement drive mechanism can be transmitted to the turret by a lever mechanism that is simple in structure, has few failures, and is easy to maintain. Therefore, according to the present invention, a turret that can reduce noise and air pollution, improve response accuracy, suppress manufacturing and operation costs, and promote the further downsizing and higher performance of a mounted machine tool. A tool post device is provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an automatic turning machine equipped with a turret tool rest device according to a first embodiment of the present invention.

FIG. 2 is a sectional front view of the turret tool rest apparatus of FIG. 1;

FIG. 3 is an enlarged partial sectional front view of the turret tool rest device of FIG. 2;

[Explanation of symbols]

 Reference Signs List 18 Tool feed stand 20 Support base 22b Rotary tool 24 Turret 28 Shaft 36 Drive shaft 38 Drive gear 40, 74 Servo motor 50 Cylindrical clutch member 54 Linear motion sleeve 56 Annular fixed coupling Element 58 ... Annular movable coupling element 60, 62 ... Teeth 72 ... Lever 76 ... Clutch gear

Claims (3)

[Claims] 1. A support base movably mounted on a machine tool along a given coordinate axis, and rotatably supported by the support base to carry a large number of tools at predetermined intervals around a rotation axis. A turret, locking means for fixedly holding the turret with respect to the support at a swivel indexing position on the support, and a first drive mounted on the support and driving a rotary tool carried by the turret. A turret tool rest device comprising: a fixed-side engaging element provided on the support base; a movable-side engaging element provided on the turret; and a movable-side engaging element. Between an engagement position that engages the stationary engagement element to prevent rotation of the turret and a disengagement position that disengages from the stationary engagement element and allows rotation of the turret. And a drive mechanism for moving the turret. A lever fixedly connected in the axial direction, and a second electric motor that moves the turret in the axial direction by swinging the lever, wherein the turret is moved in the axial direction by the driving of the second electric motor. A clutch means for operatively connecting or disconnecting the first electric motor to or from the turret, wherein the first electric motor is connected to the turret when the movable engagement element is in the disengaged position. A turret tool rest device for rotating and indexing. 2. The cylindrical clutch member, wherein the clutch means is axially fixed to the support base so as to be rotatably supported, and is fixed to the turret in the rotational direction so as to be axially movable. 2. The clutch gear according to claim 1, further comprising a clutch gear fixed to the turret in the axial direction and rotatably connected to the cylindrical clutch member, the clutch gear being connected to the first and second electric motors. 3. Turret tool post equipment. 3. The turret according to claim 1, wherein the rotating tool is mounted on a front end side surface of the turret, and the first electric motor is provided at a front end of the turret which is concentrically fixed to the driving shaft and axially penetrates the turret. The turret tool rest device according to claim 1, wherein the rotary tool is driven via a driving gear housed therein.