Acrylic round tube laser engraving machine and use method thereof

Abstract

The present invention belongs to the field of laser engraving technology, and discloses an acrylic round tube laser engraving machine, including a laser engraving machine and a laser head arranged inside the laser engraving machine. The present invention also provides a method for using the acrylic round tube laser engraving machine. The present invention places the acrylic round tube on the top of two docking plates by setting the coordination of the positioning assembly and the acrylic round tube and other structures. Through the dragging of the limit rod 1, the roller will be guided to the edge of the extension plate by the trajectory of the limit groove, and the extension plate will no longer be connected to the limit ring through the groove and the protrusion thereon. At this time, the outer periphery of the roller contacts the inner wall of the acrylic round tube, the gear is meshed with the inner gear, the gear and the roller can no longer roll, and the spring pushes the extension plate to support the side of the limit rod 1 and generate friction, so that the extension plate and the acrylic round tube are fixed as a whole, and are not easy to shake, further improving the accuracy of laser head engraving.

Description

Technical Field

[0001] The invention belongs to the technical field of laser engraving, and in particular is an acrylic round tube laser engraving machine and a use method thereof. Background Art

[0002] Laser engraving machine is a device that uses high-energy-density laser beams to engrave, cut or mark materials. It controls the movement of the laser head through a computer to accurately engrave the designed pattern or text on the surface of the material. This engraving machine can also engrave acrylic round tubes. In the existing technology, trademarks, specifications and other information of the round tube are generally engraved on it;

[0003] In existing engraving machines, an inverted V-shaped mold is generally used to limit the position of the round tube, and most of them are not equipped with a fixing fixture specifically for the round tube. This makes the acrylic round tube shake or roll due to external factors during the engraving process, which will cause the engraved pattern to deviate. For this reason, we provide an acrylic round tube laser engraving machine and a method for using it. Summary of the invention

[0004] In order to solve the problems raised in the above-mentioned background technology, the present invention provides an acrylic round tube laser engraving machine and a method of using the same, which solves the problem that most existing engraving machines are not equipped with a fixing clamp specifically for the round tube, and the acrylic round tube may shake or roll due to external factors during the engraving process.

[0005] To achieve the above object, the present invention provides the following technical solution: an acrylic round tube laser engraving machine, comprising a laser engraving machine and a laser head arranged inside the laser engraving machine, and also comprising;

[0006] A base disposed inside the laser engraving machine;

[0007] Two positioning components symmetrically hinged at both ends of the top of the base;

[0008] The positioning assembly includes a docking plate hinged on the top of the base, a limiting ring is movably installed on the docking plate, an extension plate is elastically connected to the interior of the limiting ring through a spring, a plurality of positioning grooves are equidistantly provided on the outer end of the extension plate, a plurality of limiting grooves are circumferentially provided at equal angles on the surface of the extension plate, a plurality of limiting rods are hingedly circumferentially provided at equal angles on the side of the docking plate, a roller is movably installed on the end of each of the limiting rods, the roller movably passes through the limiting groove and is transmission-connected with a gear, an internal gear is installed on the side of the limiting ring, a plurality of protrusions are fixedly provided on the interior of the limiting ring at equal angles, and a plurality of grooves matching the protrusions are provided on the side of the extension plate.

[0009] A power assembly fixed to the top of the laser engraving machine and located at the bottom of the base;

[0010] The power assembly is used to drive the limit ring to rotate;

[0011] The acrylic round tube placed on top of the two docking plates;

[0012] A collecting component is arranged on the top of the base, and the power component drives the collecting component to extract acrylic debris on the acrylic round tube.

[0013] Preferably, the inner gear is matched with the gear, the edge of the spring is inclined, the docking plate is in an inclined "L" shape, and the side of the horizontal end of the docking plate is in an arc shape.

[0014] Preferably, the power assembly includes a dual-axis motor fixedly mounted on the top of the laser engraving machine and located at the bottom of the base, each of the two ends of the dual-axis motor output shaft is transmission-connected with a bevel gear, each of the two ends of the top of the base is movably penetrated by a limit rod 2, each of the outer periphery of the limit rod 2 is movably sleeved with an adjustment cylinder, the bottom of the limit rod 2 is movably clamped with a threaded rod, the top of the limit rod 2 is hinged with a telescopic rod through a universal joint, and the output end of the telescopic rod is connected to a limit ring through a universal joint.

[0015] Preferably, every two bevel gears form a group, and there are two groups of bevel gears in total. The two bevel gears in each group are respectively arranged at one end of the output shaft of the dual-axis motor and the bottom of the threaded rod, and the pull rod part of the telescopic rod is cross-shaped.

[0016] Preferably, the threaded rod is threadably connected to the adjusting cylinder, and the upper half of the threaded rod is polygonal and inserted at the bottom of the second limiting rod.

[0017] Preferably, the collecting assembly comprises two collecting boxes symmetrically mounted at both ends of the top of the base, each collecting box is provided with a plurality of slots equidistantly disposed on one side close to the outer circumference of the acrylic tube, and a filter plate is clamped inside each collecting box.

[0018] Preferably, the collection component also includes a barrier box fixedly mounted on the top of the laser engraving machine, and both ends of the dual-axis motor output shaft are movably passed through the two barrier boxes, and both ends of the dual-axis motor output shaft are respectively connected to a fan, and the fan is located inside the barrier box. One side of the barrier box is connected to the inside of the collection box through an exhaust pipe, and the other side of the barrier box is connected to the limit ring and the extension plate through an air intake pipe.

[0019] A method for using an acrylic round tube laser engraving machine, the specific steps are as follows;

[0020] S01. Place the acrylic tube on top of the two docking plates, and then move the docking plates so that their bottoms are close to the top of the base;

[0021] S02, start the power assembly and make it drive the limit ring and the extension plate to rotate. Since the length of the limit rod 1 is fixed, the roller will be guided to the edge of the extension plate by the track of the limit groove through the drag of the limit rod 1. The limit rod 1 is also inclined and located in the positioning groove. Through the elastic force of the spring, the extension plate will no longer be connected to the limit ring through the groove and the protrusion thereon. At this time, the outer periphery of the roller contacts the inner wall of the acrylic tube, and the gear will also mesh with the inner gear.

[0022] S03, the gear and the roller can no longer roll, and the spring pushes the extension plate to support the side of the limit rod 1 and generate friction, so that the extension plate and the acrylic tube are fixed as a whole, and the laser head can start engraving.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention places the acrylic tube on the top of the two docking plates by setting the coordination of the positioning component and the acrylic tube and other structures, then moves the docking plate so that its bottom is close to the top of the base, starts the power component, and drives the limit ring and the extension plate to rotate, and the roller will be guided to the edge of the extension plate by the trajectory of the limit groove through the dragging of the limit rod 1, and the extension plate will no longer be connected to the limit ring through the groove and the protrusion thereon. At this time, the outer periphery of the roller contacts the inner wall of the acrylic tube, the gear is meshed with the inner gear, the gear and the roller can no longer roll, and the spring pushes the extension plate to support the side of the limit rod 1 and generate friction, so that the extension plate and the acrylic tube are fixed as a whole and are not easy to shake, further improving the accuracy of laser head engraving.

[0025] The present invention cooperates with structures such as a power component and a collection component. After the dual-axis motor is started, it will also drive the fans at both ends of its output shaft to rotate, thereby generating wind force. Finally, the wind force draws air inside the two collection boxes through the exhaust pipe, so that the waste chips generated by the laser head engraving the outer periphery of the acrylic round tube can be sucked into the interior of the collection box through the notch on the side of the collection box, thereby not affecting the engraving accuracy of the laser head. Furthermore, it also reduces the time for subsequent manual cleaning and greatly reduces labor.

[0026] By arranging the coordination of the positioning assembly and the collecting assembly and other structures, the wind force generated by the fan can be blown to between the limiting ring and the extension plate through the air inlet pipe, and finally blown to the inside of the acrylic round tube through the limiting groove, thereby reducing the deformation of the acrylic round tube caused by the heat generated by the laser engraving of complex patterns, which takes a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the appearance structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the top structure of the laser engraving machine of the present invention;

[0029] Figure 3 It is a schematic diagram of the transmission cooperation between the power assembly and the positioning assembly of the present invention;

[0030] Figure 4 This is a schematic diagram of the internal structure of the docking plate of the present invention;

[0031] Figure 5 It is a schematic diagram of the structure of the extension plate and the limiting ring of the present invention after being folded 180 degrees;

[0032] Figure 6 This is a schematic diagram of the coordination of the positioning groove and the limiting rod structure of the present invention;

[0033] Figure 7 This is a schematic diagram of the explosion of the power assembly structure of the present invention;

[0034] Figure 8 This is a schematic diagram of the internal structure of the collection box of the present invention;

[0035] Fig. 9 This is a schematic diagram of the explosion of the collection component structure of the present invention.

[0036] In the figure: 1. laser engraving machine; 2. laser head; 3. acrylic round tube; 4. base; 5. positioning assembly; 51. docking plate; 52. limiting ring; 53. extension plate; 54. limiting rod one; 55. roller; 56. gear; 57. spring; 58. internal gear; 59. limiting groove; 50. bump; 501. positioning groove; 6. power assembly; 61. dual-axis motor; 62. bevel gear; 63. threaded rod; 64. adjustment cylinder; 65. limiting rod two; 66. telescopic rod; 7. collection assembly; 71. collection box; 72. exhaust pipe; 73. filter plate; 74. barrier box; 75. intake pipe; 76. fan. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] like Figures 1 to 8As shown, the present invention provides an acrylic round tube laser engraving machine, comprising a laser engraving machine 1 and a laser head 2 arranged inside the laser engraving machine 1, and also comprising;

[0039] A base 4 is arranged inside the laser engraving machine 1;

[0040] Two positioning components 5 symmetrically hinged at both ends of the top of the base 4;

[0041] The positioning assembly 5 includes a docking plate 51 hinged to the top of the base 4, a limiting ring 52 is movably installed on the docking plate 51, an extension plate 53 is elastically connected to the inside of the limiting ring 52 through a spring 57, a plurality of positioning grooves 501 are equidistantly provided on the outer end of the extension plate 53, a plurality of limiting grooves 59 are circumferentially and equiangularly provided on the surface of the extension plate 53, a plurality of limiting rods 54 are hingedly circumferentially and equiangularly provided on the side of the docking plate 51, a roller 55 is movably installed on the end of each limiting rod 54, the roller 55 movably passes through the limiting groove 59 and is transmission-connected with a gear 56, an internal gear 58 is installed on the side of the limiting ring 52, a plurality of protrusions 50 are fixedly provided on the inside of the limiting ring 52 at circumferential and equiangular angles, and a plurality of grooves matching the protrusions 50 are provided on the side of the extension plate 53.

[0042] A power assembly 6 fixedly mounted on the top of the laser engraving machine 1 and located at the bottom of the base 4;

[0043] The power assembly 6 is used to drive the limiting ring 52 to rotate;

[0044] The acrylic tube 3 is placed on top of the two docking plates 51;

[0045] The collecting assembly 7 is arranged on the top of the base 4 , and the power assembly 6 drives the collecting assembly 7 to extract the acrylic debris on the acrylic tube 3 .

[0046] The inner gear 58 is matched with the gear 56, the edge of the spring 57 is inclined, the docking plate 51 is in an inclined "L" shape, and the side of the horizontal end of the docking plate 51 is in an arc shape.

[0047] Adopt the above solution: first place the acrylic tube 3 on the top of the two docking plates 51, then move the docking plates 51 so that the bottom of the acrylic tube 3 is close to the top of the base 4;

[0048] Start the power assembly 6 and make it drive the limiting ring 52 and the extension plate 53 to rotate. Since the length of the limiting rod 1 54 is fixed, the roller 55 will be guided to the edge of the extension plate 53 by the track of the limiting groove 59 through the drag of the limiting rod 1 54. The limiting rod 1 54 is also inclined and located in the positioning groove 501. Through the elastic force of the spring 57, the extension plate 53 will no longer be connected to the limiting ring 52 through the groove and the protrusion 50 thereon. At this time, the outer periphery of the roller 55 contacts the inner wall of the acrylic tube 3, and the gear 56 will also mesh with the inner gear 58.

[0049] The gear 56 and the roller 55 can no longer roll, and the spring 57 pushes the extension plate 53 to support the side of the limit rod 1 54 and generate friction, so that the extension plate 53 and the acrylic tube 3 are fixed as a whole and are not easy to shake, further improving the engraving accuracy of the laser head 2;

[0050] Similarly, after the acrylic tube 3 is engraved, if other parts need to be engraved, the power assembly 6 can be used to drive the limit ring 52 and the inner gear 58 to rotate, and the inner gear 58 drives the roller 55 to rotate through the gear 56. At this time, the acrylic tube 3 is in a rotating state, and the laser head 2 can then engrave the rest of the acrylic tube 3 again, further improving the convenience of using the device and reducing the effort of manually adjusting the position of the acrylic tube 3.

[0051] When the device completes the engraving work, the extension plate 53 can be manually rotated in the reverse direction, so that the positioning assembly 5 returns to the original state, and the acrylic tube 3 can no longer be fixed.

[0052] like Figure 1-Figure 3 and Figure 7 As shown, the power assembly 6 includes a dual-axis motor 61 fixedly mounted on the top of the laser engraving machine 1 and located at the bottom of the base 4, and both ends of the output shaft of the dual-axis motor 61 are respectively connected to a bevel gear 62 for transmission, and both ends of the top of the base 4 are each movably penetrated by a limit rod 65, and the outer periphery of each limit rod 65 is movably sleeved with an adjusting cylinder 64, and the bottom of the limit rod 65 is movably clamped with a threaded rod 63, and the top of the limit rod 65 is hinged with a telescopic rod 66 through a universal joint, and the output end of the telescopic rod 66 is connected to the limit ring 52 through the universal joint.

[0053] Every two bevel gears 62 form a group, and there are two groups of bevel gears 62 in total. The two bevel gears 62 in each group are respectively arranged at one end of the output shaft of the dual-axis motor 61 and the bottom of the threaded rod 63, and the pull rod part of the telescopic rod 66 is cross-shaped.

[0054] The threaded rod 63 is threadedly connected to the adjusting tube 64 . The upper half of the threaded rod 63 is polygonal and is inserted at the bottom of the second limiting rod 65 .

[0055] With the above solution, after the dual-axis motor 61 is started, the bevel gears 62 at both ends of its output shaft rotate, and respectively drive the two threaded rods 63 and the second limiting rod 65 to rotate, and the second limiting rod 65 drives the limiting ring 52 to rotate through the telescopic rod 66, and the positioning assembly 5 enters the working state;

[0056] It should be noted that both ends of the telescopic rod 66 are connected to the limit ring 52 and the limit rod 65 through universal joints, so that the docking plate 51 can be rotated through the telescopic rod 66 even after being tilted, further improving the smoothness of the device operation;

[0057] When the positioning assembly 5 is in a fixed state, the threaded rod 63 can be forced to descend by rotating the adjusting cylinder 64, and the two bevel gears 62 are no longer engaged, so that the dual-axis motor 61 rotates to drive the collecting assembly 7 to enter the working state. The positioning assembly 5 can still be in a fixed state and will not be affected by the power assembly 6 or the collecting assembly 7.

[0058] like Figure 1-Figure 3 and Figure 8 As shown, the collecting assembly 7 includes two collecting boxes 71 symmetrically installed at both ends of the top of the base 4, and each collecting box 71 is provided with a plurality of slots equidistantly on one side close to the outer circumference of the acrylic tube 3, and each collecting box 71 is respectively clamped with a filter plate 73 inside.

[0059] The collecting assembly 7 also includes a barrier box 74 fixedly mounted on the top of the laser engraving machine 1. Both ends of the output shaft of the dual-axis motor 61 are movable through the two barrier boxes 74. Both ends of the output shaft of the dual-axis motor 61 are respectively connected to a fan 76. The fan 76 is located inside the barrier box 74. One side of the barrier box 74 is connected to the inside of the collecting box 71 through the exhaust pipe 72, and the other side of the barrier box 74 is connected to the limit ring 52 and the extension plate 53 through the air intake pipe 75.

[0060] With the above solution, after the dual-axis motor 61 is started, it will also drive the fans 76 at both ends of its output shaft to rotate, thereby generating wind force, and finally the wind force extracts the air inside the two collection boxes 71 through the exhaust pipe 72, so that the waste generated by the laser head 2 engraving the outer periphery of the acrylic tube 3 can be sucked into the collection box 71 through the notch on the side of the collection box 71, so as not to affect the engraving accuracy of the laser head 2, further, it also reduces the time of subsequent manual cleaning, and greatly reduces the labor force;

[0061] The waste will eventually be blocked by the filter plate 73, so that it will not enter the interior of the barrier box 74 through the exhaust pipe 72 and cause damage to the fan 76, thereby extending the maintenance cycle of the device;

[0062] The wind generated by the fan 76 will also blow to between the limiting ring 52 and the extension plate 53 through the air inlet pipe 75, and finally blow to the inside of the acrylic tube 3 through the limiting groove 59, thereby reducing the deformation of the acrylic tube 3 caused by the heat generated by the laser engraving of complex patterns, which takes a long time.

[0063] A method for using an acrylic round tube laser engraving machine, the specific steps are as follows;

[0064] S01, placing the acrylic tube 3 on top of the two docking plates 51, and then moving the docking plates 51 so that the bottom of the acrylic tube 3 is in close contact with the top of the base 4;

[0065] S02, start the power assembly 6, and make it drive the limit ring 52 and the extension plate 53 to rotate. Since the length of the limit rod 1 54 is fixed, the roller 55 will be guided to the edge of the extension plate 53 by the track of the limit groove 59 through the drag of the limit rod 1 54, and the limit rod 1 54 is also inclined and located in the positioning groove 501. Through the elastic force of the spring 57, the extension plate 53 will no longer be connected to the limit ring 52 through the groove and the protrusion 50 thereon. At this time, the outer periphery of the roller 55 contacts the inner wall of the acrylic tube 3, and the gear 56 will also mesh with the inner gear 58;

[0066] S03, gear 56 and roller 55 can no longer roll, and spring 57 pushes extension plate 53 to support the side of limit rod 1 54 and generate friction, so that extension plate 53 and acrylic tube 3 are fixed as a whole, and laser head 2 can start engraving.

[0067] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0068] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An acrylic round tube laser engraving machine, comprising a laser engraving machine (1) and a laser head (2) arranged inside the laser engraving machine (1), characterized in that: Also includes; A base (4) disposed inside the laser engraving machine (1); Two positioning components (5) symmetrically hinged to the top ends of the base (4); The positioning assembly (5) comprises a docking plate (51) hinged to the top of the base (4), a limiting ring (52) movably mounted on the docking plate (51), an extension plate (53) elastically connected to the interior of the limiting ring (52) via a spring (57), a plurality of positioning grooves (501) being equidistantly formed at the outer end of the extension plate (53), a plurality of limiting grooves (59) being circumferentially equiangularly formed on the surface of the extension plate (53), and a plurality of limiting grooves (59) being circumferentially equiangularly formed on the side surface of the docking plate (51). A plurality of limit rods (54) are hingedly connected, and a roller (55) is movably mounted on the end of each limit rod (54). The roller (55) movably passes through the limit groove (59) and is transmission-connected with a gear (56). An internal gear (58) is mounted on the side of the limit ring (52). A plurality of protrusions (50) are fixedly mounted at equal angles in the inner circumferential direction of the limit ring (52). A plurality of grooves matching the protrusions (50) are formed on the side of the extension plate (53); A power assembly (6) fixedly mounted on the top of the laser engraving machine (1) and located at the bottom of the base (4); The power assembly (6) is used to drive the limiting ring (52) to rotate; An acrylic round tube (3) placed on top of the two docking plates (51); A collecting component (7) is arranged on the top of the base (4), and the power component (6) drives the collecting component (7) to extract acrylic debris on the acrylic round tube (3).

2. The acrylic tube laser engraving machine according to claim 1, characterized in that: The internal gear (58) is matched with the gear (56), the edge of the spring (57) is inclined, the docking plate (51) is in an inclined "L" shape, and the side edge of the horizontal end of the docking plate (51) is in an arc shape.

3. The acrylic tube laser engraving machine according to claim 1, characterized in that: The power assembly (6) comprises a dual-axis motor (61) fixedly mounted on the top of the laser engraving machine (1) and located at the bottom of the base (4); both ends of the output shaft of the dual-axis motor (61) are respectively connected to a bevel gear (62); both ends of the top of the base (4) are each movably penetrated by a second limit rod (65); an adjustment cylinder (64) is movably sleeved on the outer periphery of each of the second limit rods (65); a threaded rod (63) is movably clamped at the bottom of the second limit rod (65); a telescopic rod (66) is hinged to the top of the second limit rod (65) via a universal joint; and the output end of the telescopic rod (66) is connected to a limit ring (52) via a universal joint.

4. The acrylic tube laser engraving machine according to claim 3, characterized in that: Every two of the bevel gears (62) form a group, and there are two groups of bevel gears (62) in total. The two bevel gears (62) in each group are respectively arranged at one end of the output shaft of the dual-axis motor (61) and the bottom of the threaded rod (63). The pull rod part of the telescopic rod (66) is cross-shaped.

5. The acrylic tube laser engraving machine according to claim 4, characterized in that: The threaded rod (63) is threadably connected to the adjustment tube (64); the upper portion of the threaded rod (63) is polygonal and is inserted into the bottom of the second limiting rod (65).

6. The acrylic round tube laser engraving machine according to claim 3, characterized in that: The collecting assembly (7) comprises two collecting boxes (71) symmetrically mounted at two ends of the top of the base (4), each collecting box (71) having a plurality of slots equidistantly formed on one side close to the outer circumference of the acrylic tube (3), and each collecting box (71) having a filter plate (73) clamped inside.

7. The acrylic tube laser engraving machine according to claim 6, characterized in that: The collecting assembly (7) further comprises a blocking box (74) fixedly mounted on the top of the laser engraving machine (1); the two ends of the output shaft of the dual-axis motor (61) are respectively movable through the two blocking boxes (74); the two ends of the output shaft of the dual-axis motor (61) are respectively drivingly connected to a fan (76); the fan (76) is located inside the blocking box (74); one side of the blocking box (74) is connected to the inside of the collecting box (71) through an exhaust pipe (72); and the other side of the blocking box (74) is connected to the limiting ring (52) and the extension plate (53) through an air intake pipe (75).

8. A method for using an acrylic tube laser engraving machine, which is applied to the acrylic tube laser engraving machine as claimed in claim 7, characterized in that: The specific steps are as follows; S01, placing the acrylic tube (3) on top of the two docking plates (51), and then moving the docking plates (51) so that the bottom of the acrylic tube is in close contact with the top of the base (4); S02, start the power assembly (6) and make it drive the limit ring (52) and the extension plate (53) to rotate. Since the length of the limit rod 1 (54) is fixed, the roller (55) will be guided to the edge of the extension plate (53) by the trajectory of the limit groove (59) through the drag of the limit rod 1 (54). The limit rod 1 (54) is also inclined and located in the positioning groove (501). Through the elastic force of the spring (57), the extension plate (53) will no longer be connected to the limit ring (52) through the groove and the protrusion (50) thereon. At this time, the outer periphery of the roller (55) contacts the inner wall of the acrylic tube (3), and the gear (56) will also mesh with the internal gear (58); S03, the gear (56) and the roller (55) are no longer able to roll, and the spring (57) pushes the extension plate (53) to support the side of the limit rod (54) and generate friction, thereby making the extension plate (53) and the acrylic tube (3) as a whole fixed, and the laser head (2) can start engraving.

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