Machine tool gang, tool positioning device, rotary tool driving device, and machine tool

Abstract

To provide a gang which enables increase in a machining speed while assuring high accuracy machining of a piece, and a machine tool.SOLUTION: A machine tool gang (100) includes a tool support part (102), and the tool support part (102) comprises first tool installation means (105) for installing a tool (101). In the gang, the tool support part (102) has a substantially flat shape that surrounds at least partially a machining zone in which a work-piece can be machined.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The invention relates to the field of machine tools, more particularly to the field of lathes, for example automatic lathes. More particularly, in a first aspect, the invention relates to a gang for a machine tool, also called a tool support, for example a gang for an automatic lathe. More particularly, the invention relates to a gang that eliminates the need to recalibrate the position of a tool mounted on the gang when the gang is reused. In a second aspect, the invention relates to a tool positioning device for a machine tool. More particularly, the invention relates to a tool positioning device that allows a tool to be accurately and quickly positioned with respect to the bar to be machined, without the need to move the drive means of the tool positioning device during positioning. In a third aspect, the invention relates to a rotary tool drive device for a machine tool. More particularly, the invention relates to a rotary tool drive device having a magnetic gearing. Finally, in a fourth aspect, the invention relates to a machine tool, for example an automatic lathe, comprising a tool positioning device according to the invention, a gang according to the invention and / or a rotary tool drive device according to the invention. [Background technology]

[0002] During the machining of machine parts by machine tools, especially precision machine tools such as automatic lathes, it is essential that the tools required for machining the desired part can be positioned very accurately with respect to the bar to be machined. Furthermore, nowadays it is necessary to be able to perform this positioning as quickly as possible in order to reduce the total machining time and thus ultimately reduce machining costs and increase the speed of production of parts.

[0003] Tool positioning devices for machine tools known from the prior art usually comprise two independent linear directional guides for the movement of one or more tools or of the carriage on which these tools are mounted. Typically, these linear directional guides of known machines are preferably oriented at right angles to each other and are coupled to respective motors that allow the movement of the tool relative to the bar to be machined. By combining the translational movements of these two linear directional guides, the tool can be moved in any direction in a plane perpendicular to the bar.

[0004] However, the prior art positioning devices have major drawbacks. In practice, the linear direction guides are arranged in a "series" state, which means that one of the two linear direction guides and its respective motor must be moved by the other linear direction guide. This means that large masses, especially the motor mass, must be moved whenever the tool is positioned. This is a drawback, since it means that the movement times for positioning the tool with respect to the bar to be machined are increased. Finally, this limits the machining speed. Moreover, if the tool is moved at high speed, it is difficult to position the tool accurately due to the high inertia of such a system. Finally, axis stacks, i.e. axes arranged in series, have a lower stiffness than parallel structures.

[0005] Gangs, so-called tool supports known from the prior art, usually consist of a tool support, for example in the form of a metal plate on which a tool holder is mounted. The tool holder is usually designed to receive a plate, i.e. a plate holder, on which the cutting tool itself is finally mounted.

[0006] The known gangs are capable of achieving high machining precision, but are bulky and heavy. The high mass of the known gangs results in long positioning times for positioning the tools relative to the bar to be machined. Furthermore, the geometry and dimensions of these known gangs result in large movements having to be performed in order to position the various tools required for machining the part near the bar to be machined. Naturally, these displacements limit the machining speed. Furthermore, the gangs known in the prior art are only intended for tool holders oriented essentially parallel to one another. The known gangs are therefore intended for tools arranged next to one another. In the case of large gangs with many tools, the tools positioned at the ends of the gang are located far away from one another. If, during machining, a first one of these tools is used and then another tool is used, the gang has to be moved over a relatively large distance, i.e. the positioning times increase and, naturally, the machining speed is limited. Finally, the gangs known in the prior art are characterized by a large distance between the attachment point of the tools on the gang and the point of application. This may lead to deformation of the tool during machining, which may result in poor machining quality.

[0007] Rotary tool drives for machine tools known in the prior art generally use mechanical gearing to rotate the tool. Mechanical gearing has the drawback of generating a lot of vibration, noise and heat. High-precision mechanical gearing is very expensive. Moreover, mechanical gearing allows only limited acceleration and deceleration of the rotationally driven tool. Furthermore, the devices of the prior art are large in size and heavy in weight, which means long movement times when these devices have to be moved during machining. Moreover, the high mass of the known devices makes it impossible to move these devices in the minimum time while ensuring high-precision positioning.

[0008] Machine tools known in the prior art that include tool positioning devices, gangs, and / or rotary tool drive devices are not capable of machining high precision parts at very high speeds: in fact, the mass and / or dimensions of these elements limit the achievable machining speed and machining accuracy.

[0009] There is therefore a need for a tool positioning device, a rotary tool drive device for a machine tool, a gang, and a machine tool that allows for increased machining speeds while ensuring high accuracy in the machining of the pieces. Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the invention is therefore to propose a gang for a machine tool, a tool positioning device, a rotary tool drive device and a machine tool, which make it possible to overcome the aforementioned constraints. [Means for solving the problem]

[0011] According to the invention, these objects are achieved by the subject matter of the four independent claims. More particular aspects of the invention are set out in the independent claims and in the description.

[0012] More specifically, the object of the invention is achieved by a gang for a machine tool comprising a tool support, the tool support comprising first tool mounting means for mounting a tool, characterized in that the tool support has a substantially planar shape at least partially surrounding a machining zone in which a workpiece can be machined.

[0013] Such a gang allows the tools mounted on the gang to be as close as possible to the bar to be machined, which reduces the gang movements required for machining the part and therefore increases the machining speed. Furthermore, the gang according to the invention allows the size of the gang to be reduced compared to gangs known in the prior art carrying the same number of tools. Furthermore, the reduced dimensions result in a lower mass. This allows the gang to be moved faster and with greater precision.

[0014] According to a first preferred embodiment of this aspect of the invention, the tool support has an at least partially elliptical, circular or polygonal shape, which allows a large number of tools to be arranged as close as possible to the bar to be machined.

[0015] According to another preferred embodiment of the invention, the tool support has a closed frame shape, which makes it possible to provide the gang with a high degree of rigidity, which makes it possible to ensure that the position of the tool on the gang remains constant throughout the entire machining process.

[0016] According to another preferred embodiment of the invention, the first tool mounting means is configured for mounting a tool in the form of a plate. This allows the plate to be mounted directly on the tool support without the need to use a tool holder or a plate holder. It is therefore possible to reduce the required travel size of the gang during machining, thus increasing the machining speed. It is also advantageous to realize that the first tool mounting means is further configured for mounting tools such as drill bars and drill bits for internal machining.

[0017] According to a next preferred embodiment of the invention, the gang comprises support mounting means provided for mounting the tool support to a tool positioning device of the machine tool, preferably to a positioning device according to the invention. It is therefore possible to mount and remove the gang to and from the positioning device of the machine tool in such a way that the gang always assumes the same position. It is therefore possible to start machining immediately after mounting the gang to the machine tool, thus increasing the machining speed.

[0018] According to yet another preferred embodiment of the invention, the gang comprises a second tool mounting means for mounting the first rotary tool and / or a third tool mounting means for mounting the second rotary tool. Such a gang comprises all the tools necessary for machining a complex part. It is therefore possible to have one gang per workpiece. This allows to quickly change the gang and start machining as soon as possible whenever another part has to be machined.

[0019] According to another preferred embodiment of the invention, the second tool mounting means is configured such that the first rotating tool has an axis of rotation parallel to the plane containing the tool support, which makes it possible to provide tools for machining, for example, holes, threads or milled surfaces, perpendicular to the axis of the bar to be machined.

[0020] According to a next preferred embodiment of the invention, the third tool mounting means is configured such that the second rotating tool has an axis of rotation which forms an acute angle with the surface containing the first tool support of more than 0°, advantageously more than 30°, even more advantageously more than 60°, preferably 90°, which makes it possible to provide tools for machining highly complex parts.

[0021] According to a next preferred embodiment of the invention, the gang is provided with a reference marking, advantageously an optical marking, which makes it possible to calibrate the position of the tools mounted on the gang relative to said optical marking and also to determine the position of the gang itself.

[0022] According to another preferred embodiment of the invention, the gang is provided with identification means, advantageously a code imprinted on the tool support, making it possible to identify the gang in a unique way, thus making it possible to associate a specific gang with a specific part.

[0023] According to another preferred embodiment of the invention, the gang comprises information storage means making it possible to store the position of the tools on the gang, the number of tools, the type of tools, the cutting direction of the tools, the unique identifier of the gang, the number of workpieces machined by the gang, the date of determination of the position of the tools on the gang, the programs for machining the workpieces and / or the date of use of the gang. This makes it possible to store any information useful for machining a part and also to trace the history of the gang. The storage of the tool positions on the gang makes it possible, by means of reading this corresponding information, to retrieve this information which can be entered into the machine tool so that machining of the part can begin.

[0024] According to the next preferred embodiment of the invention, the gang comprises communication means allowing the transmission and reception of information to and from the information storage means, thereby allowing communication between the gang and the machine tool or the calibration device, and it is possible to realize that the communication means are adapted to communicate with laptops, smartphones and for communication via a telecommunication network or the Internet.

[0025] According to the following preferred embodiment of the invention, the communication means are wireless means, preferably based on RFID technology, thus making it possible to communicate with the gang in a remote manner, thus making it possible to read the information contained in the gang, for example by means of a smartphone.

[0026] According to another preferred embodiment of the invention, the gang comprises at least one plate, a first rotary tool and / or a second rotary tool. Such a gang allows to completely machine complex parts.

[0027] According to another preferred embodiment of the invention, the first rotary tool and / or the second rotary tool are rotationally driven by a rotary tool drive device according to the invention, which makes it possible to use rotary tools with smaller dimensions, thereby increasing the machining speed.

[0028] Furthermore, the object of the invention is a positioning system for a machine tool for positioning a tool relative to a machine tool zone, comprising a first linear directional guide and a second linear directional guide, the translational movement directions of which are parallel with respect to the first linear directional guide and the second linear directional guide, a carriage designed to receive the tool, a first inclined linear directional guide mounted relative to the first linear directional guide, the translational movement direction of which forms an angle of more than 0° with the translational movement direction of the first inclined linear directional guide, and a second inclined linear directional guide mounted relative to the second linear directional guide, the translational movement direction of which forms an angle of more than 0° with the translational movement direction of the second inclined linear directional guide. This is achieved by a positioning system comprising a second inclined linear direction guide, the first and second inclined linear direction guides forming an angle of greater than 0° therebetween and the translational movement direction for the first and second inclined linear direction guides forming a plane parallel to the translational movement direction for the first and second straight linear direction guides, a first drive means provided for translating the first inclined linear direction guide by acting on the first straight linear direction guide, and a second drive means provided for translating the second inclined linear direction guide by acting on the second straight linear direction guide, the second drive means being mounted on the first and second inclined linear direction guides, characterized in that the translational movement plane of the first straight linear direction guide and the translational movement plane of the second straight linear direction guide intersect.

[0029] Such a positioning device allows the tool of a machine tool to be positioned accurately and in a minimum amount of time with respect to the bar to be machined. The main advantage of the positioning device according to the invention is obtained by the fact that the drive means, e.g. motors, required for positioning are arranged topologically in parallel and not in series, as in the devices known in the prior art. Due to this parallel configuration, none of the drive means are displaced during positioning. This makes it possible to realize a positioning device with a significantly reduced mass displaced during positioning, compared to the devices known in the prior art. The reduced mass ensures that the tool can be positioned in a minimum amount of time while still guaranteeing a high positioning accuracy. Furthermore, due to the coupling of the first inclined linear direction guide to the second inclined linear direction guide by the carriage, a higher degree of stiffness and therefore a high machining accuracy is achieved.

[0030] Furthermore, the combination of a straight linear direction guide and an inclined linear direction guide makes it possible to perform displacement in any direction contained within the plane formed by the translational movement directions for the first straight linear direction guide and the second straight linear direction guide.

[0031] Finally, the advantage of intersecting the translational plane of the first linear directional guide with the translational plane of the second linear directional guide is obtained by the compactness of the shaft structure and its force loop, which is favorable for its stiffness and precision. This compactness leads to a further weight reduction, which allows for an increase in dynamics and therefore speed. It should be noted that, although the intersection of these planes is very favorable, it is still possible to make the translational planes of the first linear directional guide and the second linear directional guide parallel but not intertwined.

[0032] According to a first preferred embodiment of the second aspect of the present invention, the angle formed by the translational movement direction relative to the first straight linear direction guide and the first inclined linear direction guide is greater than 20°, advantageously greater than 30°, preferably equal to or greater than 45°, and / or the angle formed by the translational movement direction relative to the second straight linear direction guide and the second inclined linear direction guide is greater than 20°, advantageously greater than 30°, preferably equal to or greater than 45°.

[0033] The conversion of the displacement along the first straight linear direction guide to a displacement perpendicular to the first straight linear direction guide is proportional to the angle formed by the translation direction with respect to the first straight linear direction guide and the first inclined linear direction guide. A larger angle results in a larger displacement along the first straight linear direction guide in the vertical direction. The same is true for the angle formed by the translation direction with respect to the second straight linear direction guide and the second inclined linear direction guide.

[0034] According to another preferred embodiment of the invention, the angle between the translation direction with respect to the first inclined linear directional guide and the translation direction with respect to the second inclined linear directional guide is between 60° and 120°, preferably between 70° and 110°, advantageously 90°. These values ​​allow to change the geometry of the machining zone in the translation plane of the carriage and thus fix the tool in an advantageous position, for example. These values ​​also allow to change the resolution and dynamics, i.e., depending on the angle value selected, a gear-down / deceleration effect is obtained between the resolution / dynamics applied to the input motor and the resolution / dynamics obtained in the area perpendicular to the tool located at the kinematic output position, in a certain direction of the translation plane of the carriage. This gear-down / deceleration effect also allows these forces to be changed between the kinematic input position and the kinematic output position.

[0035] According to another preferred embodiment of the invention, the positioning system comprises a first slide between the first straight linear directional guide and the first inclined linear directional guide and a second slide between the second straight linear directional guide and the second inclined linear directional guide. The presence of these slides between the straight linear directional guide and the inclined linear directional guide allows angular transmission between these elements. This allows the straight linear directional guides to be aligned such that the carriage of the positioning device, and thus the tool, can be located in the immediate vicinity of the barrel of the machine tool. This allows further shortening of the positioning distance, which ensures high speed and high dynamics of machining.

[0036] According to another preferred embodiment of the present invention, the intersection line of the translational movement plane of the first linear directional guide and the translational movement plane of the second linear directional guide intersects the machining zone of the machine tool. This minimizes the lever arm, thereby reducing the negative effects of errors in the axis and frame geometry at the machining point. This therefore maximizes the accuracy of the axis structure at the machining point.

[0037] According to another preferred embodiment of the invention, the positioning system comprises sensors for measuring the speed, acceleration and / or position of the first straight linear direction guide, the second straight linear direction guide, the first inclined linear direction guide, the second inclined linear direction guide and / or the carriage. These sensors make it possible to know the exact position of the carriage or the tool at any time. Furthermore, if position sensors are provided on the inclined linear direction guides, it becomes possible to know the absolute position of the carriage relative to the machine tool and thus of the tool mounted on the carriage without the need to perform a calibration.

[0038] According to the following preferred embodiment of the invention, these sensors are of the optoelectronic, interferometric, velocity measurement, acceleration and / or tilt scanning scale type, making available all the information necessary to guarantee high-precision positioning, thus making it possible to increase the machining speed and, for example, to determine upper / lower limits for positioning parameters that guarantee machining of an acceptable quality.

[0039] According to another preferred embodiment of the invention, the carriage has a Young's modulus expressed in GPa and a density of kg / m 3 The carriage is at least partially made of a material having a Young's modulus to density ratio, expressed as , of more than 0.010, advantageously more than 0.015, preferably more than 0.020, and / or a damping coefficient of more than 0.0010, advantageously more than 0.0015, preferably more than 0.0020. This ensures that the carriage is as light as possible while having a maximum stiffness. It should be noted that the damping coefficient is preferably determined by measuring the response of the material after being struck by an impact hammer. By providing the carriage with a minimum mass and a maximum stiffness, it is possible to increase the dynamics, i.e. to reduce the positioning time while increasing the positioning accuracy. Suitable materials are, for example, cast iron or spheroidal graphite cast iron, preferably of the EN-GJS-400 type. Furthermore, composite materials, for example materials containing fibers and polyester resins, as well as carbon, for example spun carbon fibers, are suitable for manufacturing the carriage of the positioning system according to the invention.

[0040] Furthermore, the object of the invention is achieved by a rotary tool driving device comprising a first subframe of substantially cylindrical shape, a second subframe, also of substantially cylindrical shape and positioned at one end of the first subframe, the longitudinal axis of the first subframe and the longitudinal axis of the second subframe forming an obtuse angle of less than 180 degrees, and tool clamping means provided for clamping a tool, characterized in that the device comprises a magnetic gearing positioned at the interface between the first and second subframes, the magnetic gearing comprising an input wheel arranged in the first subframe and capable of being driven in rotation about the longitudinal axis of the first subframe, and an output wheel arranged in the second subframe and capable of being driven in rotation about the longitudinal axis of the second subframe, the input wheel and the output wheel being magnetically coupled, the input wheel being arranged to drive in rotation the output wheel, and the tool clamping means being arranged to be driven in rotation by the output wheel of the magnetic gearing.

[0041] The rotary tool drive device according to the invention makes it possible to provide a rotary tool with an angular transmission between the motor which drives the tool in rotation and the tool itself. This provides a great deal of freedom in the geometry of the rotary tool, making it possible to position the rotary tool as close as possible to the bar to be machined. Positioning the rotary tool in the immediate vicinity of the bar to be machined makes it possible to minimize the movements necessary to machine the part, thus increasing the machining speed. Furthermore, the positioning accuracy can be improved due to the smaller displacements.

[0042] According to a first preferred embodiment of this third aspect of the invention, the magnetic gearing is of the bevel type, worm type, external spur gear type, internal spur gear type, spiral bevel gear type or planetary gear type, which allows the type of magnetic gearing to be adapted to the specific rotary tool to be driven, and which allows the gear type to be adapted to the geometry of the drive device.

[0043] According to another preferred embodiment of this third aspect of the invention, the obtuse angle formed by the longitudinal axis of the first sub-frame and the longitudinal axis of the second sub-frame is less than 150°, advantageously less than 120°, preferably 90°. Such an angle allows the rotary tool to be oriented in any direction required for machining highly complex pieces without the need to pivot or translate the drive device itself.

[0044] According to another preferred embodiment of the invention, the tool clamping means comprises clamping jaws which can be translated by a hydraulic system in a direction perpendicular to the tool's axis of rotation. By means of such a hydraulic clamping system, very high clamping forces on the rotary tool can be ensured, which can thus be held in a fixed position during the machining process, thus ensuring precise machining.

[0045] According to a next preferred embodiment of the invention, the clamping jaws can be translationally driven by a deformable clamping membrane in response to pressure changes of the hydraulic fluid of the hydraulic system. The clamping membrane has the advantage that it allows a very precise movement of the clamping jaws relative to the rotating tool. Thus, the force applied by the clamping jaws to the tool can be precisely adjusted. Furthermore, the clamping jaws can ensure the concentricity of the tool with respect to the axis of rotation.

[0046] According to another preferred embodiment of the invention, the pressure of the hydraulic fluid is adjustable by means of a pressure means, for example a hydraulic screw, the longitudinal axis of which is substantially parallel to the longitudinal axis of the second sub-frame. This pressure means being provided such that its longitudinal direction is substantially parallel to the longitudinal axis of the second sub-frame and thus of the rotary tool, allows easier access to said means and therefore easier adjustment of the hydraulic fluid pressure.

[0047] The object of the invention is also achieved by a machine tool comprising a tool positioning device, a gang and / or a rotary tool according to the invention. Such a machine tool makes it possible to achieve high machining speeds while guaranteeing high precision of the machined parts. The positioning device allows the tool to be moved in any direction in a minimum amount of time and with high precision. The gang allows all tools required for machining a part to be located in the immediate vicinity of the part, which limits the amount of tool displacement and therefore increases the machining speed and precision. This also applies to the rotary tool device, which allows the tool to be positioned as close as possible to the bar to be machined.

[0048] According to a first preferred embodiment of the fourth aspect of the invention, the machine tool comprises a movable headstock for driving the bar to be machined in rotation along its longitudinal axis, by means of which the bar to be machined can be rotated in a simple yet precise manner.

[0049] According to yet another preferred embodiment of the invention, the movable headstock is configured to translate the bar to be machined in a direction parallel to the longitudinal axis of the bar to be machined. The movable headstock capable of translating the bar to be machined allows the part to be machined without the need for other means of translating the bar.

[0050] According to a next preferred embodiment of the invention, the machine tool comprises communication means arranged to communicate with the communication means of the gang. The communication means of the machine tool allow the information contained in the gang to be transmitted to the machine tool. Thus, for example, when the gang is mounted on the machine tool, the information contained in the gang, such as for example the gang's identifier, the number of tools on the gang, the tool type, the tool position and also the machining program, is automatically transmitted to the machine tool. The machine tool automatically receives all the information necessary for machining the piece and machining can start immediately.

[0051] The specific features and advantages of the present invention will become clear in more detail within the context of the following description, including examples of implementations, presented by way of example and not limitation with reference to the 13 accompanying drawings. [Brief description of the drawings]

[0052] [Figure 1] FIG. 1 is a first view perspective view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention; [Diagram 2] FIG. 2 shows a front view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention; [Diagram 3] FIG. 11 is a second view of a partially exploded perspective view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention. [Figure 4] FIG. 11 is a third view of a partially exploded perspective view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention. [Diagram 5]FIG. 13 is a partially exploded front view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention; [Figure 6] FIG. 13 is a front view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention, with the carriage of the positioning device moved in a linear direction; [Figure 7] FIG. 13 is a front view of a machine tool according to a preferred embodiment of the fourth aspect of the invention, a positioning device according to a preferred embodiment of the second aspect of the invention, and a gang according to a preferred embodiment of the first aspect of the invention, with the carriage of the positioning device moved in a diagonal direction; [Figure 8] FIG. 13 is a front view of a machine tool according to a preferred embodiment of the fourth aspect of the present invention, a positioning device according to a preferred embodiment of the second aspect of the present invention, and a gang according to a preferred embodiment of the first aspect of the present invention, with the carriage of the positioning device moved horizontally; [Figure 9] FIG. 1 is a first view perspective view of a gang according to a second preferred embodiment of the first aspect of the present invention, fitted with a cutting tool and a rotary tool; [Figure 10] FIG. 13 is a rear view of a gang according to a second preferred embodiment of the first aspect of the present invention, fitted with a cutting tool and a rotary tool; [Figure 11] FIG. 13 is a perspective view of a second view of a gang according to a second preferred embodiment of the first aspect of the present invention, fitted with a cutting tool and a rotary tool. [Figure 12] FIG. 11 is a side cross-sectional view of a drive device for a rotary tool according to a preferred embodiment of the third aspect of the present invention. [Figure 13] FIG. 13 is a perspective cross-sectional view of a drive device for a rotary tool according to a preferred embodiment of the third aspect of the present invention; [Figure 14]FIG. 13 is a third view perspective view of a gang according to a second preferred embodiment of the first aspect of the present invention, fitted with a cutting tool and a rotary tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Figure 1 shows in a perspective view a first view of a machine tool 1, here an automatic lathe, according to a first embodiment of this aspect of the invention. The automatic lathe 1 comprises a frame 2, a barrel 3, preferably fixed in this mode of realization, a movable headstock (not shown) allowing the clamping of the bar to be machined and its rotational and translational drive along an axis z corresponding to the longitudinal axis of the bar, and a gang 100 carrying the tools 101 (see further Figure 2) required for machining. Preferably, the gang 100 is mounted on a carriage 207, which is part of a positioning device 200 of the invention that allows the tool 101 to be positioned accurately and in a minimum amount of time with respect to the bar being machined.

[0054] First, the structural and functional features of a positioning device 200 of the present invention will be described with reference to FIGS.

[0055] FIG. 2 shows a front view of a machine tool 1 equipped with a positioning device 200 according to a first embodiment of this aspect of the invention. As can be seen, the device 200 comprises a carriage 207 configured to allow the gang 100 to be mounted. In the home position of the positioning device 200, i.e. in the position in which the carriage 207 is positioned symmetrically with respect to the bar to be machined, the gang 100 is likewise positioned symmetrically with respect to the barrel 3 of the machine tool 1 and thus symmetrically with respect to the bar to be machined (not shown here). In this figure, the x-, x'-, x''-, y- and z-axes are illustrated, which will be used hereinafter to explain the working principle of the positioning system 200. The y-axis will be called hereinafter the vertical axis, the x-axis will be called hereinafter the horizontal axis, the x'-axis will be called hereinafter the first tilt axis and the x''-axis will be called hereinafter the second tilt axis. As can be seen in this figure, the tilt axes x' and x'' form a right angle in this embodiment.

[0056] 3-5 show a partially exploded bottom perspective view, a partially exploded front perspective view and a partially exploded front view of the machine tool 1 and the positioning device 200, respectively. The positioning device 200 comprises a first straight linear direction guide 201 and a second straight linear direction guide 202, which in this embodiment are arranged symmetrically with respect to the z-axis on the inclined surfaces 2a and 2b of the frame 2 of the machine tool 1 (see FIG. 3). It is important to note that the presence of these inclined surfaces 2a and 2b is not essential for the operation of the positioning device 200. The first straight linear direction guide 201 and the second straight linear direction guide 202 may be mounted on the surface of the frame 2 in a normal direction with respect to the z-axis. However, the presence of the inclined surfaces 2a and 2b allows the slides 203 and 204 to be provided between the straight linear direction guides and the inclined linear direction guides. This allows the tool 101 to be positioned closer to the barrel 3 of the machine tool 1, so that workpieces with very small dimensions can be machined without tool offsets. Advantageously, the slides 203 and 204 are made of a very stiff and light material, for example cast iron, preferably EN-GJS-400-15. Furthermore, these slides 203 and 204 are preferably hollowed out in order to limit as much as possible their weight, respectively their bulkiness. Furthermore, as can be seen, preferably the carriage 207 is also hollowed out, thereby limiting its weight, respectively its bulkiness.

[0057] As shown in Figures 3 to 5, the first inclined linear directional guide 205 and the second inclined linear directional guide 206 are mounted on the first slide 203 and the second slide 204, respectively. The slides 203 and 204 are designed such that the translational movement directions x' and x'' for the first inclined linear directional guide 205 and the second inclined linear directional guide 206 form a plane normal to the z-axis, i.e. normal to the longitudinal axis of the bar to be machined. Furthermore, the carriage 207, which is connected to the inclined linear directional guides 205 and 206, is provided such that the tool 101, which is preferably mounted on the carriage 207 via the gang 100, is moved only in a plane normal to the z-axis.

[0058] Furthermore, the device 200 comprises a first linear drive motor and a second linear drive motor (not shown in the drawings) which act on the first slide 203 and the second slide 204 respectively via a first ball screw coupling 201a and a second ball screw coupling 202a to drive the first slide 203 and the second slide 204 parallel to the vertical axis y.

[0059] The principle of operation of the positioning device 200 will now be explained with the aid of FIGS. 1 and 6 to 8 which show the carriage 207 and therefore the tool 101 in various positions relative to the barrel 3 and the bar to be machined.

[0060] As mentioned above, Fig. 2 shows the "home" position of the carriage 207 relative to the barrel 3, i.e. the position in which the carriage 207 is positioned symmetrically relative to the bar to be machined. When the slides 203 and 204 are driven synchronously, i.e. at the same speed and in the same direction, by the first straight linear directional guide 201 and the second straight linear directional guide 202, along a direction A that is parallel to the vertical axis y, the carriage 207 itself is also driven in translation parallel to the axis y. Thus, the synchronous movement of the slides 203, 204 can adjust the y-axis position of the tool 101 as shown in Fig. 6.

[0061] On the other hand, when only one of the slides 203, 204 is driven in translation parallel to the vertical axis y, for example the first slide 203 is driven via the respective straight linear direction guide in the direction A as shown in FIG. 7, the carriage 207 is not only linearly translated parallel to the y axis direction, but also horizontally translated parallel to the x axis. The carriage is therefore moved diagonally in such a case. Indeed, due to the second slide 204 being united with the straight linear direction guide 202 via the second motor 202b, the second slide 204 cannot translate along the direction A in response to the movement of the first slide 203. However, in response to the movement of the first slide 203 in the direction A, the carriage 207 is driven in the direction B relative to the first slide 203 parallel to the first tilt axis x' and in the direction C relative to the second slide 204 parallel to the second tilt axis x''. It should be noted that in this embodiment, the positioning device 200 is configured symmetrically, resulting in equal amounts of displacement along directions B and C. Thus, displacement of the first slide 203 along direction A, while the second slide 204 remains stationary, ultimately results in a "diagonal" displacement of the carriage 207, i.e., a displacement having a component along the horizontal x-axis and a component along the vertical y-axis.

[0062] Translational movement of the carriage 207 parallel to the horizontal axis x is achieved by translating the first slide 203 and the second slide 204 in opposite parallel directions A and D. For example, with reference to Figure 8, displacement of the carriage 207 only along the E direction, without moving it along the y axis, is achieved by translational movement of the first slide 203 along the A direction, accompanied by an equal amount of translational movement of the second slide 204 in the D direction. In a similar manner, displacement of the carriage 207 in the horizontal direction F is achieved by translational movement of the second slide 204 in the A direction, and translational movement of the first slide 203 in the D direction.

[0063] As can be seen from the above description of the working principle of the positioning device 200, by combining the directions and amounts of displacement of the first slide 203 and the second slide 204 only in a direction parallel to the linear y-axis, it is possible to move the carriage 207 and thus the tool 101 in any direction in the plane defined by the x- and y-axes. It is thus possible to position any tool 101 mounted directly on the carriage 207 or on the gang 100 in the position required for machining the workpiece.

[0064] One of the great advantages of the positioning device 200 over known devices of the prior art is that the linear direction guides necessary to move the tool in any direction are arranged topologically in "parallel" rather than "in series". In the devices known in the prior art, the linear direction guides and their drive motors are arranged in series, which means that at least one of the drive motors must always be moved simultaneously with the carriage 207. Therefore, in order to be able to position the tool with respect to the bar to be machined, the mass of the motor, which is generally high compared to the mass of the other elements of the positioning device, must be moved. This means that the known positioning devices of the prior art have a high inertia, which limits not only the shortest time but also the accuracy with which positioning can be performed. In fact, the high inertia makes it more difficult to decelerate a carriage that is moved at high speed. In contrast, with the positioning device of the present invention, the motors are fixed and do not need to be moved. Thus, only the carriage, the slide and the tool need to be moved, which makes it possible to limit the total mass or bulk that has to be moved when positioning the tool. This allows much shorter positioning times and therefore faster machining speeds to be achieved whilst ensuring high positioning accuracy and therefore machining accuracy.

[0065] Figures 9 to 11 and 14 show a gang 100 for a machine tool according to a first embodiment of this aspect of the invention. The gang 100 comprises a tool support 102 with six substantially rectangular tool mounting plates 104a to 104f connected together by corners 106. The tool support 102 in the embodiment shown in these figures therefore takes the form of a square frame with truncated corners. Within the scope of the invention, the tool support 102 can have another substantially flat shape that at least partially surrounds a machining zone in which a workpiece can be machined. Thus, within the scope of the invention, a different number of tool mounting plates can be provided. The shape of these plates can also differ from that shown in Figures 9 to 11 and 14. They can have an arch shape. In this case, the tool support 102 can take the form of a ring or a crown. Of course, the tool support 102 can also have a polygonal shape, such as a triangle, a square, a rectangle, a pentagon, a hexagon, a heptagon, an octagon or any other type of regular or irregular polygon. It is not essential for the present invention that the frame formed by the tool support 102 has a closed configuration. The only important point is that the shape of the tool support can at least partially enclose the zone in which the piece is to be machined.

[0066] As can be seen in figures 9 to 11 and 14, mounting supports 103 are mounted against the outer edges of the four tool mounting plates 104a, 104b, 104d, 104e. Advantageously, these mounting supports 103 comprise pins 103a intended to cooperate with corresponding holes provided on a machine tool or a tool positioning device, for example with the carriage 207 of the inventive positioning system 200. Furthermore, the mounting supports 103 comprise positioning holes 103b intended to cooperate with pins of a machine tool or a tool positioning device, for example with the inventive positioning device 200. It is thus possible to position and mount the gang 100 relative to the machine tool, ensuring that the supports 102 take up a well-defined position relative to the machine tool and / or the carriage of the machine tool.

[0067] Furthermore, tool mounting means 105 are provided on each tool mounting plate 104a-104f. In the illustrated embodiment, the gang 100 comprises a total of 24 tool mounting means 105. Naturally, a different, greater or lesser number of tool mounting means 105 can be provided without departing from the scope of the invention. These tool mounting means 105 are configured such that a tool 101, here in the form of a plate 101a, can be mounted directly on the tool mounting plates 104a-104f of the gang 100. In contrast to gangs known in the prior art, no plate or tool holder is required here. However, it is important to note that it is possible to provide spacers between the plate 101a and the tool mounting plates 104a-104f in order to adjust the distance between the plate 101a and the mounting plates without departing from the scope of the invention. The direct mounting of the plate 101a to the tool support 102 allows for a tool support 102 with a small frame width 102D (see FIG. 9), thus limiting the mass and dimensions of the gang 100. Furthermore, the direct mounting of the plate 101a to the tool support 102 reduces the size of the path that the gang 100 must follow when machining the part, thus allowing for faster machining.

[0068] As can be seen from figures 9-11 and 14, the tool support 102 is designed with tool mounting plates 104a-104b oriented along at least two different directions forming an angle β between them. In the embodiment shown in these figures, an angle β1 of 90° is set, for example between the tools 101 arranged on the tool mounting plates 104a and 104b, while an angle β2 of 45° exists between the tool mounting plates 104a and 104f (see figure 10). The possibility of orienting the tools 101 arranged on the mounting plates in at least two different directions allows a very large number of tools on a single gang and reduces the translational distance that the gang must travel when machining a part. This in turn allows for an increased machining speed. As mentioned above, the geometry of the gang 100 in the embodiment shown in these figures should not be considered limiting. The desired technical effect is achieved by a gang with a tool support having a shape that can at least partially surround the machining zone. For example, the gang 100 may be implemented as an open ring or a closed ring without departing from the scope of the present invention.

[0069] In the embodiment shown in Figures 9 to 11 and 14, the tool support 102 is designed such that the mounting plates 104a to 104f form a closed frame. This has the advantage that the gang 100 has a very high rigidity. This rigidity of the tool support 102 ensures that the relative positions of the tools 101 mounted on the gang 100 remain constant with respect to each other. Naturally, the tool support 102 can be realized in various geometries without departing from the scope of the invention. As mentioned above, a gang according to the invention can comprise only two tool mounting plates 104a to 104b oriented with respect to each other to form an obtuse angle of less than 180°.

[0070] As can be seen in Figures 9 to 11 and 14, the gang 100 comprises not only tools 101 in the form of a plate 101a, for example a chisel, but also further rotary tools 101b and 101c, for example for machining holes or threads. The gang 100 may comprise first rotary tools 101b, whose axis of rotation is parallel to the plane defined by the support 102. In an advantageous way, the axis of rotation of the first rotary tools lies in the same plane as the plate 101a. These first rotary tools 101b may take the form of angled pins, as shown in Figure 14. Such angled pins may take the form of, for example, a drive device 300 of the invention for rotary tools. The gang also comprises second rotary tools 101c, whose axis of rotation lies outside the plane defined by the plate 101a. Advantageously, the axis of rotation of the second rotary tool 101c is perpendicular to the plane defined by the plate 101a. The second rotating tool 101c can be either mounted directly to the tool support 102 or via a rotating tool support 107 which is mounted to the tool support 102. Providing a separate rotating tool support 107 allows for a higher total number of tools on the gang 100 and / or allows for the rotating tool 101b or 101c to be changed without changing the position of the tool 101a on the tool support 102. The gang 100 is designed to carry all the tools required to machine a piece. It is therefore possible to consider having one gang per workpiece. This allows for faster machining speeds as changeover between parts can be made more quickly.

[0071] As mentioned above, the gang 100 preferably includes pins 103a and locating holes 103b that allow it to be repeatedly loaded and unloaded from a particular machine tool while ensuring that the tools 101 are always in the same position relative to one another. Of course, the removable design of the gang 100 also allows the same gang 100 to be used on multiple machine tools.

[0072] As mentioned above, the gang 100 is designed so that the relative positions of the tools 101 do not change even if the gang is removed and remounted to one or more machine tools. This is very advantageous because if the gang 100 is reused, the relative positions of the tools do not have to be determined again, and machining of the workpiece can be started immediately without recalibration with significant time loss. Indeed, in the field of machining of high precision machine parts, calibration is a process that generally requires a lot of attention and time. However, in order for the tools 101 mounted on the gang 100 to be able to be used for the production of high precision workpieces, it is important to determine the absolute position of the tools 101 on the gang 100 once during calibration, preferably relative to a reference marking on the gang 100. This reference marking can be, for example, an optical marking on the gang, for example a cross or a uniform shape. Of course, the determination of the absolute position of the tools on the gang can also be made relative to a reference element of the gang, for example one of the pins 103a. During calibration, it is also important to determine the machining direction, e.g., cutting direction, of each tool 101 mounted on the gang 100.

[0073] It is important to note that the determination of the absolute position of the tool 101 on the gang 100 can be performed either independently of the machine tool by a dedicated calibration machine, for example an optical calibration machine, or directly on the machine tool by machining calibration pieces with the gang 100 and subsequently analyzing the machining results of these calibration pieces.

[0074] To facilitate the reuse of the gang 100, it is advantageously envisaged that the gang will be provided with a unique identification means enabling it to identify itself. This identification means can be a number or a code stamped or otherwise placed on a part of the gang, for example on the tool support 102. This number can then be suggested to the machine tool on which the gang 100 is mounted, by being manually introduced by a person handling the machine tool on which the gang 100 is mounted. Preferably, the machine tool has a database capable of identifying the gang. This database can include, for example, the absolute and / or relative positions of the tools 101 for each known gang. In fact, it can be envisaged that all the absolute positions of the tools on the gang are known and recorded in the database. Also, the absolute position of a single tool or of a single reference point, such as the optical marking mentioned above, as well as the relative position of the tool with respect to this reference element can be known and recorded in the database.

[0075] Preferably, the gang 100 has information storage means (not shown in the drawings) capable of storing and storing the absolute and / or relative positions of the tools 101 on the gang 100 and a unique identifier of this gang. In this case, the gang 100 may be equipped with electronic communication means in order to transmit this information and any other information to the machine tool when the gang is mounted on this machine tool. These electronic communication means may be wired, such as for example in the form of suitable connectors provided on the gang and on the machine tool, such as in the form of electronic connectors, or wireless, such as for example in the form of RFID chips or other equivalent means known to the skilled person. It is noted that advantageously, the information storage means may be configured to contain, in addition to the position of the tools and the machining direction of the tools, information such as for example the number of pieces machined by this gang, the date of use of this gang, the date of tool replacement, the date of calibration, a list of the machines on which the gang has been used, and / or the workpieces corresponding to the gang. Of course, this list is not limiting. Preferably, this storage means may be configured to further contain a CAD file describing the corresponding workpiece. Moreover, the electronic communication means of the gang 100, preferably wired or wireless, can be configured to allow one-way or two-way communication between the gang 100 and the means for reading the data contained in the storage means. These reading means can be provided, for example, in a dedicated calibration machine for calibrating the gang, or in any other device, such as a mobile communication means, for example, a smartphone. This allows for a quick reading of the information contained in the storage means and for example for identifying a particular gang and the corresponding workpiece. The communication storage means provided in the gang allows for the information stored in the gang to be automatically transmitted to the machine tool when the gang is mounted on a machine tool having equivalent communication means. For example, it can be expected that a CAD file describing the workpiece and the corresponding machining program, both stored in the gang's storage means, will be transmitted to the machine tool.The machine tool is then ready to start machining without the need for an operator to enter these data.

[0076] As mentioned above, once a calibration has been performed, i.e. once the position of the tool 101 has been determined relative to the reference point, the gang 100 can be used for several machine tools without the need to perform a new calibration. Moreover, it is important to highlight that the gang 100 has another advantage with regard to the calibration: in fact, if a tool 101 of the gang 100 needs to be replaced, for example after a breakage, it is only necessary to determine the position of the replacement tool relative to this reference point, making it possible to know all the relative positions.

[0077] Figures 12 and 13 show cross-sectional views of a drive device 300 for a rotary tool according to a preferred embodiment of this aspect of the invention. The device 300 comprises a frame 301 sub-divided into a first sub-frame 301a and a second sub-frame 301b, both of which are of a substantially cylindrical shape. As can be seen in these figures, the second sub-frame 301b is positioned at the end of the first sub-frame 301a and forms with it an obtuse angle α of less than 180°. In this particular embodiment, the obtuse angle α is equal to 90°. Of course, it is possible to set angles α other than 90° within the scope of the invention.

[0078] The device 300 also comprises a magnetic gear set comprising an input wheel 302a arranged in the first sub-frame 301a and an output wheel 302b arranged in the second sub-frame 301b. The input wheel 302a is configured such that it can be driven in rotation about a longitudinal axis w of the first sub-frame 301a at high speed, for example by an electric motor (not shown here). A person skilled in the art can easily imagine how an electric motor can be provided in the first sub-frame 301a to drive in rotation the input wheel 302a of the magnetic gear set 302.

[0079] The input wheel 302a and the output wheel 302b are magnetically coupled. In other words, the input wheel 302a and the output wheel 302b comprise magnetic elements that generate a magnetic coupling between them. The magnetic coupling between the input wheel 302a and the output wheel 302b allows the output wheel 302b to be driven to rotate about the longitudinal axis v of the second sub-frame 301b via the input wheel 302a.

[0080] The device 300 also comprises clamping means 303 provided for clamping and releasing a tool 304, for example a drill. The clamping means 303 is coupled to the output wheel 302b such that the clamping means 303 and therefore the tool 304 can be driven in rotation about the longitudinal axis v of the second sub-frame 301b by the magnetic gearing 302.

[0081] Preferably, the clamping means 303 comprises a clamping jaw 305 which can be translated in a direction perpendicular to the axis v. Advantageously, the clamping jaw 305 can be translated by a flexible membrane (not shown here) coupled to a hydraulic system. In one advantageous way, the flexible membrane 306 is deformable in response to pressure changes of the hydraulic fluid of the hydraulic system. By adjusting the pressure of this fluid, the flexible membrane can be deformed more or less, thereby making it possible to adjust the position of the clamping jaw 305 and thus the clamping force of the jaw 305 on the tool 304 and / or the release force of the tool 304. In this embodiment, the pressure of the hydraulic fluid can be adjusted in an advantageous way by an adjusting screw (not shown here) screwed into a thread 307 provided coaxially to the tool 304 but at the opposite end of the second subframe 301b.

[0082] The rotary tool driving device 300 according to the invention is advantageous over the devices known from the prior art, since it allows the drive motor of the device not to be arranged coaxially with respect to the tool 304 to be driven in rotation. This allows the machining of complex pieces, for example with a thread parallel to the axis of the bar to be machined, by a machine tool that only comprises a positioning device that allows the displacement of a rotary tool, but also a cutting tool, for example the positioning device 200 according to the invention. Furthermore, advantageously, the rotary tool driving device 300 can be combined with the gang 100 according to the invention. The device 300 allows the movements required by the gang during the machining of complex pieces to be minimized. This allows the machining speed to be increased.

[0083] It is obvious that the invention is susceptible to numerous variations in its implementation. Non-limiting embodiments have been shown by way of example, with the understanding that it is of course not conceivable to comprehensively identify all possible variations. Of course, it is conceivable to replace the means described with equivalent means without departing from the scope of the invention. All these modifications form part of the common knowledge of a person skilled in the art of machine tools. [Explanation of symbols]

[0084] 1. Machine tools, automatic lathes 2 Frames 2a Slope 2b Slope 3 barrels 100 Gang 101 Tools 101a Plates, tools 101b Rotary tool, first rotary tool 101c Rotary tool, second rotary tool 102 Tool support part 102D Frame Width 103 Mounting support part 103a Pin 103b Positioning hole 104a Tool mounting plate 104b Tool mounting plate 104c Tool mounting plate 104d Tool mounting plate 104e Tool mounting plate 104f Tool mounting plate 105 Tool mounting means 106 Corner 107 Rotary tool support 200 Positioning device, positioning system 201 First straight line direction guide 201a first ball screw coupling 202 Second Linear Direction Guide 202a Second ball screw coupling 202b Second motor 203 First Slide 204 Second Slide 205 First Inclined Linear Direction Guide 206 Second Inclined Linear Direction Guide 207 Carriage 300 Rotary tool drive device 301 Frames 301a First subframe 301b Second subframe 302 Magnetic Gear Device 302a Input Wheel 302b output wheel 303 Clamping means 304 Tools 305 Clamp Jaw 306 Flexible Membrane 307 Thread

Claims

1. A gang (100) for a machine tool, comprising a tool support (102), the tool support (102) comprising a first tool mounting means (105) for mounting a tool (101), The gang (100) is characterized in that the tool support (102) has a substantially planar shape at least partially surrounding a machining zone within which a workpiece can be machined.

2. 2. The gang (100) of claim 1, wherein the tool support (102) has an at least partially elliptical, circular, or polygonal shape.

3. 3. The gang (100) according to claim 1 or 2, wherein the tool support has a closed frame shape.

4. 4. The gang (100) according to any one of claims 1 to 3, wherein the first tool mounting means (105) is configured for mounting a tool (101) in the form of a plate (101a).

5. A gang (100) according to any one of claims 1 to 4, comprising support mounting means (103) provided to enable mounting of the tool support (102) to a tool positioning device of a machine tool, preferably to a positioning device (200) according to any one of claims 1 to 4.

6. 6. The gang (100) according to any one of claims 1 to 5, comprising a second tool mounting means for mounting a first rotary tool (101b) and / or a third tool mounting means for mounting a second rotary tool (101c).

7. 7. The gang (100) of claim 6, wherein the second tool mounting means is configured such that the first rotating tool (101b) has an axis of rotation parallel to a plane including the tool support portion (102).

8. The gang (100) according to claim 6, wherein the third tool mounting means is configured such that the second rotating tool (101c) has an axis of rotation that forms an acute angle of more than 0°, advantageously more than 30°, even more advantageously more than 60°, preferably 90°, with a plane including the first tool support part (102).

9. A gang (100) according to any one of the preceding claims, comprising fiducial markings, advantageously optical markings.

10. A gang (100) according to any one of the preceding claims, comprising identification means making it possible to identify the gang in a unique manner, advantageously a code imprinted on the tool support part (102).

11. 11. The gang (100) according to any one of claims 1 to 10, comprising information storage means enabling to store the position of the tools on the gang, the number of tools, the type of tools, the cutting direction of the tools, a unique identifier of the gang, the number of workpieces to be machined by the gang, the date of determination of the position of the tools on the gang, a program for machining workpieces, and / or the date of use of the gang.

12. A gang (100) according to any one of the preceding claims, comprising communication means enabling transmission of information to and reception of information from said information storage means.

13. The gang (100) according to claim 12, wherein said communication means are wireless means, preferably based on RFID technology.

14. 14. The gang (100) according to any one of claims 1 to 13, comprising a plate (101a), a first rotary tool (101b) and / or a second rotary tool (101c).

15. A machine tool (1) comprising a gang (100) according to any one of claims 1 to 14.

16. 16. The machine tool (1) according to claim 15, comprising a movable headstock for driving in rotation the bar to be machined along its longitudinal axis.

17. 17. The machine tool (1) according to claim 15 or 16, wherein the movable headstock is configured to translate the bar to be machined in a direction parallel to a longitudinal axis of the bar to be machined.

18. 18. A machine tool (1) according to any one of claims 15 to 17, comprising communication means arranged to communicate with communication means of the gang.

Images