阅读说明：本技术 印刷装置 (Printing device ) 是由 后藤裕行 丸山要一 菊地秀昭 大木繁 于 2019-09-20 设计创作，主要内容包括：本发明提供即使被印刷件倾斜也能够在准确的位置进行印刷的印刷装置。一种用于在由输送机(1)输送的钢板(2)的上表面进行印刷的印刷装置(A),该印刷装置(A)具有：印刷部(B),其具有在钢板的上表面进行印刷的印刷头(10)；倾斜检测部(C),其对钢板的倾斜进行检测；厚度检测部(D),其对钢板的厚度进行检测；两端侧高度检测部(E),其对钢板的下游侧的端部且宽度方向两端侧附近的高度进行检测；形变检测部(F),其对钢板的厚度方向的形变进行检测；输送速度检测部(G),其对钢板的输送速度进行检测；以及控制部(35),其预先存储有包含应印刷的被印刷件的板厚在内的规格数据以及印刷数据,并根据由倾斜检测部(C)检测出的钢板的倾斜来对印刷数据的坐标进行变换,且控制成使得印刷部(B)以与由厚度检测部(D)检测出的厚度对应的方式升降。(The invention provides a printing device capable of printing at an accurate position even if a printing object is inclined. A printing device (A) for printing on an upper surface of a steel sheet (2) conveyed by a conveyor (1), the printing device (A) comprising: a printing unit (B) having a printing head (10) for printing on the upper surface of the steel sheet; an inclination detection unit (C) that detects the inclination of the steel plate; a thickness detection unit (D) that detects the thickness of the steel sheet; a both-end-side height detection unit (E) that detects the height of the downstream-side end of the steel sheet in the vicinity of both ends in the width direction; a strain detection unit (F) that detects strain in the thickness direction of the steel sheet; a conveying speed detection unit (G) that detects the conveying speed of the steel sheet; and a control unit (35) which stores in advance specification data including the thickness of the material to be printed and print data, converts the coordinates of the print data in accordance with the inclination of the steel plate detected by the inclination detection unit (C), and controls the printing unit (B) to move up and down in accordance with the thickness detected by the thickness detection unit (D).)

1. A printing apparatus for printing on an upper surface of a member to be printed conveyed by a conveyor,

the printing apparatus is characterized by comprising:

a printing section including a beam portion that spans a conveyor and is immovable, and a printing head that is mounted on the beam portion so as to be movable and liftable in a conveying direction of the conveyor and a direction crossing the conveyor, and that prints on an upper surface of a material to be printed conveyed by the conveyor;

an inclination detection unit which is disposed upstream of the printing unit in the conveying direction of the conveyor and detects an inclination of the conveyed printing target;

a thickness detection unit which is disposed upstream of the printing unit in the conveying direction of the conveyor and detects the thickness of the material to be printed;

a both-end-side height detecting section which is disposed on the upstream side of the printing section in the conveying direction of the conveyor and detects the height of the both ends in the width direction near the downstream end of the printing target;

a plurality of strain detection units arranged in a direction crossing the conveyor at a position upstream of the printing unit in the conveying direction of the conveyor, and configured to detect a strain in a thickness direction of the material to be printed;

a conveyance speed detection unit which is disposed upstream of the printing unit in the conveyance direction of the conveyor and detects a conveyance speed of the material to be printed; and

and a control unit that stores in advance print target data including a thickness of a print target to be printed and print data for the print target, converts coordinates of the print data in accordance with the inclination of the print target detected by the inclination detection unit, and controls the print unit to move up and down in accordance with the thickness detected by the thickness detection unit.

2. Printing device according to claim 1,

the printing portion has: a first carriage mounted on the beam section and traversing in a direction intersecting a conveying direction of the conveyor; and a second carriage mounted on the first carriage and reciprocating along a conveying direction of the conveyor, wherein the print head is mounted on the second carriage so as to be able to move up and down.

3. Printing device according to claim 1 or 2,

the inclination detection unit includes: a longitudinal end detection member which is arranged on the upstream side of the printing portion in the conveying direction of the conveyor and detects a longitudinal end of the printing object; and a width direction end detection member that is disposed upstream in the transport direction from the longitudinal direction end detection member and detects a width direction end of the printing material, wherein the inclination detection unit detects the inclination of the printing material by synchronizing the detection of the length direction end of the printing material by the longitudinal direction end detection member with the detection of the width direction end of the printing material by the width direction end detection member.

4. A printing device according to any one of claims 1 to 3,

the both-end-side height detection unit includes a pair of distance detection members disposed so as to be movable in a direction crossing the conveying direction of the conveyor, and detects the height of both end portions of the printing material by detecting the distance from the surface of the printing material by the pair of distance detection members.

5. Printing device according to one of claims 1 to 4,

the strain detection unit includes a plurality of distance detection members arranged in a direction crossing the conveyor, and detects a strain in the thickness direction of the material to be printed by detecting a distance between the distance detection members and an upper surface of the material to be printed that faces the distance detection members.

6. Printing device according to one of claims 1 to 5,

the transport speed detecting unit includes a rotating body that rotates in accordance with movement of a printing object transported by a transport conveyor while being in contact with a surface of the printing object, and detects the transport speed of the printing object by detecting rotation of the rotating body.

Technical Field

The present invention relates to a printing apparatus for printing characters, numerals, symbols, or figures including lines on a material to be printed conveyed by a conveyor.

Background

In the shipbuilding industry, the steel industry, or the shearing (shearing) industry, an operation of printing characters, numerals, lines, or the like, which become information related to cutting and welding, on the surface of a steel plate is performed. When printing on a steel plate, generally, the steel plate is stopped in advance in a work area, and a print head is moved two-dimensionally while printing predetermined characters, numbers, lines, or the like. A printing apparatus for performing such printing is configured to include: a platform for placing a steel plate; a trolley that travels along the platform; a carriage that traverses a platform mounted on a carriage in a direction that the platform traverses; and a print head mounted on the carriage (see, for example, patent document 1).

On the other hand, the invention described in patent document 2 relates to a marking device capable of marking a plate material conveyed by a conveying device. The scribing device is provided with: a plate thickness detection sensor, a plate lug detection sensor and a plate surface height detection sensor for a plate material, wherein the plate material is conveyed by a conveying device; and a dot mark head. The point marking heads are distributed over the entire lower surface of the marking device in the direction transverse to the transport device, so that marking can be carried out simultaneously over the entire width of the moving sheet material.

The spot marking head is moved up and down in accordance with the plate thickness detected by the plate thickness detection sensor to maintain an optimum height, and the spot marking head is moved in the direction of traversing the conveying device in accordance with the position of the lug detected by the lug detection sensor, and the marking of the plate material is performed in this state. In particular, the plate surface height detection sensor is disposed on the lower surface of the marking device in the same manner as the spot marking head, and the plate surface height detection sensor detects a local change in the plate material immediately before the plate material is marked, and makes the marking device meet the change.

Patent document 2 describes a configuration in which a pre-coat factory primer coating dryer is disposed upstream of a conveyor. Therefore, the coating, drying, and marking after drying of the pre-coat factory primer on the panel can be performed as a series of operations. Therefore, a special work space for marking, a plate material conveying facility, and the like are not required, and rational work can be performed.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 2574110

Patent document 2: japanese patent No. 2736604

Summary of the invention

Problems to be solved by the invention

The invention described in patent document 1 has a problem that a dedicated working space and dedicated equipment such as a transport facility such as a crane are required.

In the invention described in patent document 2, the marking device includes a support device including a lateral sliding mechanism and a lifting mechanism, and the support device is configured to simultaneously slide laterally and lift dot marking heads arranged in a direction crossing the conveyance device. Therefore, when the plate material is deformed in the height direction, distances between the dot heads and the plate material may become unequal, and as a result, the marks may become unclear.

The invention aims to provide a printing device which can print at a correct position even if a printing object inclines.

Means for solving the problems

In order to solve the above problem, a printing apparatus according to the present invention is a printing apparatus for printing on an upper surface of a material to be printed conveyed by a conveyor, the printing apparatus including: a printing section including a beam portion that spans a conveyor and is immovable, and a printing head that is mounted on the beam portion so as to be movable and liftable in a conveying direction of the conveyor and a direction crossing the conveyor, and that prints on an upper surface of a material to be printed conveyed by the conveyor; an inclination detection unit which is disposed upstream of the printing unit in the conveying direction of the conveyor and detects an inclination of the conveyed printing target; a thickness detection unit which is disposed upstream of the printing unit in the conveying direction of the conveyor and detects the thickness of the material to be printed; a both-end-side height detecting section which is disposed on the upstream side of the printing section in the conveying direction of the conveyor and detects the height of the both ends in the width direction near the downstream end of the printing target; a plurality of strain detection units arranged in a direction crossing the conveyor at a position upstream of the printing unit in the conveying direction of the conveyor, and configured to detect a strain in a thickness direction of the material to be printed; a conveyance speed detection unit which is disposed upstream of the printing unit in the conveyance direction of the conveyor and detects a conveyance speed of the material to be printed; and a control unit that stores in advance print target data including a thickness of a print target to be printed and print data for the print target, converts coordinates of the print data in accordance with the inclination of the print target detected by the inclination detection unit, and controls the print unit to move up and down in accordance with the thickness detected by the thickness detection unit.

In the above printing apparatus, it is preferable that the printing unit includes: a first carriage mounted on the beam section and traversing in a direction intersecting a conveying direction of the conveyor; and a second carriage mounted on the first carriage and reciprocating along a conveying direction of the conveyor, wherein the print head is mounted on the second carriage so as to be able to move up and down.

In any of the above printing apparatuses, it is preferable that the inclination detection unit includes: a longitudinal end detection member which is arranged on the upstream side of the printing portion in the conveying direction of the conveyor and detects a longitudinal end of the printing object; and a width direction end detection member that is disposed upstream in the transport direction from the longitudinal direction end detection member and detects a width direction end of the printing material, wherein the inclination detection unit detects the inclination of the printing material by synchronizing the detection of the length direction end of the printing material by the longitudinal direction end detection member with the detection of the width direction end of the printing material by the width direction end detection member.

In any of the above printing apparatuses, it is preferable that the both-end-side height detecting section includes a pair of distance detecting members disposed so as to be movable in a direction crossing the conveying direction of the conveyor, and detects the height of the both end portions of the material to be printed by detecting the distance from the surface of the material to be printed by the pair of distance detecting members.

In any of the above printing apparatuses, it is preferable that the distortion detection section includes a plurality of distance detection members arranged in a direction crossing the conveyor, and detects a distortion in a thickness direction of the material to be printed by detecting a distance between the distance detection members and an upper surface of the material to be printed which faces the distance detection members.

In any of the above printing apparatuses, it is preferable that the conveyance speed detecting unit includes a rotating body that rotates in accordance with movement of the printing material while being in contact with the surface of the printing material conveyed by the conveyor, and detects the conveyance speed of the printing material by detecting rotation of the rotating body.

Effects of the invention

In the printing apparatus of the present invention, characters, numerals, symbols, figures including lines, and the like can be accurately printed on the upper surface of the material to be printed conveyed by the conveyor. That is, in the printing apparatus of the present invention, when printing is performed on the material to be printed, the inclination of the material to be printed with respect to the conveyance direction, the plate thickness, the height of both end portions in the width direction, and the conveyance speed of the material to be printed are detected on the upstream side in the conveyance direction from the printing section. Therefore, the coordinate of the print data to be printed or the height of the print head from the transport surface can be converted in accordance with the detected conditions such as the posture and deformation of the printing target, and printing can be performed.

Further, since the print head is configured to be movable up and down while traversing in a direction intersecting the conveyance direction of the conveyor and reciprocating in the conveyance direction, it is possible to cope with the detected deformation in the height and thickness directions of the both end portions of the material to be printed during the printing on the material to be printed. In particular, in the process of printing in the direction crossing the transport direction, even when the print head is moved up and down, the difference in the distances between the nozzles constituting the print head and the printing object is small, and therefore, a problem does not occur in the formed print.

Further, the inclination detection unit can detect the end in the width direction in synchronization with the detection of the end on the downstream side of the printing target by the longitudinal end detection means, and therefore can reliably detect the inclination of the printing target.

Further, the inclination detection unit detects the distance from the printing object when the widthwise end is detected by the widthwise end detection means, and therefore can detect the amount of deviation of the printing object with respect to the lateral direction intersecting the conveying direction of the conveyor. The print data can be compensated for by this deviation amount. That is, by shifting the print data by the shift amount, printing can be accurately performed at a desired position.

The both-end-side height detecting section detects the distance between the surface of the printing material and the pair of distance detecting members disposed so as to be movable in the direction crossing the conveying direction of the conveyor, and therefore can detect the twist and the local height difference even when the printing material is twisted. Therefore, the height of the print head can be adjusted by using the height of both end portions in the width direction in addition to the thickness of the material to be printed detected by the thickness detection unit.

Further, since the strain detection unit detects the strain in the thickness direction of the printing material, the print head can be adapted to the detected strain of the printing material.

Further, since the transport speed detecting unit includes the rotating body that rotates while contacting the surface of the material to be printed, and detects the rotation of the rotating body, the transport speed of the material to be printed is detected, and therefore, even when a slip occurs between the transport speed detecting unit and the transport surface of the conveyor, it is possible to execute printing by detecting an actual accurate transport speed and controlling the moving speed of the printing head based on the detected transport speed.

Drawings

Fig. 1 is a schematic plan view illustrating the structure of the printing apparatus of the present embodiment.

Fig. 2 is a side view of fig. 1.

Fig. 3 is a schematic front view for explaining the structure of the printing portion.

Fig. 4 is a schematic front view illustrating the structure of the thickness detection unit.

Fig. 5 is a schematic front view illustrating the structure of the both-end side height detecting unit.

Fig. 6 is a block diagram illustrating the configuration of the control unit.

Detailed Description

The printing apparatus of the present invention detects the inclination of a printing object such as a steel plate, for example, conveyed by a conveyor with respect to the conveying direction, and the warp, strain, and the like of the printing object to the outside of the surface, and drives a print head in accordance with the detected inclination, warp, and strain, or passes the printing object without printing.

Hereinafter, the printing apparatus of the present embodiment will be described with reference to the drawings. The printing apparatus a shown in fig. 1 prints characters, numerals, symbols, or figures including lines at predetermined positions on the upper surface of a printing material (hereinafter referred to as "steel plate 2") such as a steel plate conveyed in the direction of arrow X (hereinafter also referred to as "downstream direction" or "conveying direction") by a conveyor 1.

For this purpose, the printing apparatus a is configured to include: a printing unit B for printing on the steel sheet 2; an inclination detection unit C that detects an inclination of the steel plate 2; a thickness detection unit D for detecting the thickness of the steel plate 2; a both-end-side height detection section E that detects the height of the steel sheet 2 in the vicinity of the downstream end 2a and in the vicinity of the width-direction ends 2b1, 2b 2; a strain detection unit F that detects strain in the thickness direction of the steel sheet 2, for example, warpage; and a conveyance speed detection unit G for detecting the conveyance speed of the steel sheet 2.

The conveyor 1 conveys the steel sheet 2 in the arrow X direction. Therefore, the structure is not limited as long as the steel plate 2 can be placed and conveyed. As such a conveyor, there are a roller conveyor, a slat conveyor, a belt conveyor, and the like, but a roller conveyor is preferable in consideration of the weight, warpage, and the like of the steel sheet.

In the present embodiment, a roller conveyor in which a plurality of rollers are arranged is used as the conveyor 1, and the steel plate 2 is conveyed by driving the rollers at a predetermined conveying speed.

The state of the surface of the steel sheet 2 is not limited, and may be a black skin state, a state after rust removal, or a state after coating. In the present example, a steel sheet having a surface coated with an anticorrosive coating is used as the steel sheet 2. That is, a sand blasting device and a coating device are provided on the upstream side in the conveying direction of the conveyor 1, the surface of the steel sheet 2 is cleaned while passing through these devices, and the cleaned surface is coated with an anticorrosive paint. For this purpose, the steel sheet 2 is conveyed at a speed suitable for the blast treatment and the coating treatment.

The printing unit B is disposed on the most downstream side in the printing apparatus a. The printing unit B includes a movable printing head 10, and by driving the printing head 10 while moving in the direction crossing the conveyor 1 and the conveying direction, printing can be performed at a predetermined position of the steel sheet 2 being conveyed.

The printing section B has a beam portion 11 provided across the conveyor 1. A first carriage 12 is mounted on the beam portion 11, and the first carriage 12 is configured to be driven by a first carriage drive motor 12a so as to be capable of traversing in a direction intersecting the conveying direction (arrow X direction) of the conveyor 1. A second carriage 13 is mounted on the first carriage 12, and the second carriage 13 is configured to be movable in the conveying direction of the conveyor 1 by being driven by a second carriage drive motor 13 a. Further, an elevating carriage 14 is disposed on the second carriage 13, the elevating carriage 14 is configured to be movable up and down in a vertical direction (arrow Z direction, hereinafter also simply referred to as "vertical direction") of the conveyor 1 by being driven by an elevating motor 14a, and the printing head 10 is mounted on the elevating carriage 14. Therefore, the print head 10 can be moved three-dimensionally by driving the drive motors 12a and 13a and the lifting motor 14 a.

The print head 10 is not limited in structure as long as it has a function of printing characters, numerals, symbols, or figures including lines on the upper surface of the steel plate 2. As such a print head, there are a linear marking head that performs linear printing by ejecting ink from individual nozzles, and a dot marking head that performs marking by selectively ejecting ink from a plurality of nozzles arranged in a matrix. In this embodiment, a dot marking head is utilized.

The first carriage 12 is configured to be able to move the print head 10 mounted thereon in the lateral direction by a distance that satisfies a preset maximum width dimension of the steel plate 2. Then, the state of being retracted to the initial position set on either one end side in the width direction of the conveyor 1 is normally maintained.

The second carriage 13 is set to have a length corresponding to the conveying speed of the conveyor 1 for conveying the steel plate 2 and the maximum width of the steel plate 2. Then, the state of being retracted to the initial position set at the end on the upstream side in the conveying direction of the conveyor 1 is normally maintained.

The lifting carriage 14 normally maintains a state in which the print head 10 is retracted to an initial position set as a lifting limit.

The operation when printing on the steel plate 2 is started with the first carriage 12, the second carriage 13, and the lifting bracket 14 at the initial positions will be described. First, the print head 10 is lowered by the lifting carriage 14 until the distance (height) from the upper surface of the steel plate 2 becomes a predetermined dimension. Next, while the second carriage 13 and the print head 10 are caused to traverse in the arrow Y direction (hereinafter also referred to as "the width direction of the conveyor 1") by the first carriage 12, the second carriage 13 and the print head 10 are caused to move in the arrow X direction by the second carriage 13 in accordance with the conveying speed of the steel plate 2. By driving the print head 10 during this movement, printing on the steel plate 2 can be performed.

The inclination detection unit C is disposed upstream of the printing unit B in the conveying direction of the conveyor 1, and detects the inclination of the steel sheet 2 being conveyed before the steel sheet 2 reaches the printing unit B. For this purpose, the inclination detection unit C includes: a longitudinal end detection member 18 that detects the end 2a on the downstream side in the longitudinal direction of the steel plate 2; and a pair of widthwise end surface detection means 19a, 19b which are disposed upstream in the transport direction from the lengthwise end detection means 18 and detect a widthwise end surface 2c which is an end of the printing material in the widthwise direction.

The detection mechanism of the steel plate 2 constituted by the longitudinal end detection member 18 and the width end detection members 19a and 19b is not limited, and may be a contact sensor or a noncontact sensor. In the present embodiment, a noncontact laser sensor is used as each detection member.

The longitudinal end detecting member 18 is disposed above the conveyor 1 in the vertical direction and substantially at the center in the width direction. The pair of widthwise end surface detection members 19a and 19b are disposed on one side in the width direction of the conveyor 1 and above the conveying surface of the conveyor 1, and are disposed in parallel with each other in the center direction of the conveyor 1 at a predetermined distance from each other. Further, by synchronizing the detection of the longitudinal end 2a of the steel plate 2 by the longitudinal end detecting means 18 with the detection of the width-directional end 2c of the steel plate 2 by the width-directional end detecting means 19a, 19b, the inclination of the steel plate 2 with respect to the conveying direction can be detected.

The coordinates of the print data on the steel plate 2 stored in advance are converted by the control unit 35 described later based on the inclination of the steel plate 2 detected by the inclination detection unit C, and the print head 10 can be driven and controlled by the converted print data.

The thickness detection unit D is disposed upstream of the printing unit B in the conveying direction of the conveyor 1, and detects the thickness of the steel sheet 2 conveyed by the conveyor 1 before the steel sheet 2 reaches the printing unit B. For this purpose, the thickness detection unit D includes a thickness detection means 20 for detecting the thickness of the steel plate 2. The thickness detection member 20 is formed of a laser sensor, and is disposed substantially at the center in the width direction of the conveyor 1 in the vertical direction.

The thickness detection member 20 is disposed at a position at a predetermined height H from the conveying surface (surface connecting the apexes of the parallel rollers) of the conveyor 1 in the vertical direction of the conveyor 1. The thickness t of the steel plate 2 can be detected from the difference between the preset height H and the distance H when the surface of the steel plate 2 is detected.

Based on the thickness t of the steel plate 2 detected by the thickness detection unit D, the control unit 35, which will be described later, compares the thickness of the steel plate 2 stored in advance with the detected thickness t, and lowers the print head 10 so that the distance from the surface of the steel plate 2 becomes the optimum height for printing. In particular, when the detected thickness t of the steel plate 2 is different from the thickness stored in advance, it is determined that the steel plate is not a printing target, and the printing portion B is controlled to pass through.

The timing of detecting the thickness of the steel plate 2 by the thickness detecting means 20 is not particularly limited, but it is preferable to synchronize the detection of the longitudinal end 2a of the steel plate 2 by the longitudinal end detecting means 18 in the inclination detecting portion C. However, in this case, the distance between the thickness detection member 20 and the longitudinal-direction end detection member 18 is limited by the length of the steel plate 2. Therefore, the detection of the thickness t of the steel plate 2 by the thickness detection means 20 and the detection of the longitudinal end 2a of the steel plate 2 by the longitudinal end detection means 18 are not necessarily synchronized.

As described above, when printing is performed on the steel plate 2, the height of the printing head 10 from the surface of the steel plate 2 is set in accordance with the thickness t of the steel plate 2 detected by the thickness detection section D. In this case, if the steel sheet 2 is flat in the width direction and the longitudinal direction, the surface is also flat, and smooth printing can be performed. However, the steel sheet 2 cannot be ensured to be flat over the entire surface. Further, in the thickness detection section D, since the thickness detection member 20 is disposed at the substantially center in the width direction of the conveyor 1, when the steel plate 2 is warped in the width direction, there is a risk that the end portion of the warped steel plate 2 collides with the print head 10. Therefore, the both-end height detection section E detects the height of the steel plate 2 in the vicinity of both ends in the width direction, thereby detecting the warpage of the steel plate 2.

The both-end-side height detecting section E is disposed on the upstream side of the printing section B in the conveying direction of the conveyor 1, and detects the height of the vicinity of both ends in the width direction on the downstream side of the steel sheet 2 being conveyed before the steel sheet 2 reaches the printing section B. The height of the print head 10 can be corrected by the difference between the detected heights hb1 and hb2 near both ends in the width direction of the steel plate 2 and the thickness t of the steel plate 2 detected by the thickness detection unit D, and printing can be performed.

The both-end-side height detection section E has a pair of distance detection members 23a, 23b configured to be movable in a direction crossing the conveyor 1, and is configured to be capable of detecting the height of the steel sheet 2 by detecting the distance from the surfaces of the vicinities 2b1, 2b2 of both ends in the width direction of the steel sheet by the pair of distance detection members 23a, 23 b. The vicinity of the end in the width direction of the steel sheet 2 is not strictly limited to the dimension from the end 2a in the longitudinal direction and the dimension from the end face 2c in the width direction, and may be substantially in the vicinity of the end.

Therefore, the pair of distance detection members 23a and 23b are configured to be movable to positions facing the vicinity of the ends in the width direction of the steel plate 2 conveyed by the conveyor 1. That is, stands (stands) 24 are provided at positions facing each other on both sides in the conveying direction of the conveyor 1, and arms 25a and 25b that are driven by drive motors 26a and 26b and move in the direction in which the conveyor 1 traverses are arranged on the stands 24. Distance detection members 23a and 23b are attached to the distal ends of the arms 25a and 25 b.

Each of the distance detecting members 23a and 23b is formed of a laser sensor similarly to the thickness detecting member 20, and is disposed at a position having a predetermined height H from the conveying surface of the conveyor 1 in the vertical direction of the conveyor 1. The heights hb1 and hb2 in the vicinity of the ends in the width direction of the steel sheet 2 can be detected from the difference between the preset height H and the distance at which the surface in the vicinity of the ends is detected.

The both-end-side height detection section E is not limited to simply detecting the height of only the vicinity of the end in the width direction of the steel plate 2, but is preferably configured such that the arm 25a or the arm 25b is continuously dispatched in the direction crossing the conveyor 1 and is changed in position in the width direction of the steel plate 2, thereby being able to detect the height. In particular, the height of the steel plate 2 is detected in advance by correlating the lateral position of the printing head 10, which changes as the printing on the steel plate 2 progresses, with the conveyance speed of the steel plate 2, and the height of the printing head 10 can be corrected in accordance with the detected height.

The strain detection unit F is disposed upstream of the printing unit B in the conveying direction, and detects the strain in the thickness direction by detecting the irregularities in the width direction of the steel sheet 2. That is, as described above, the steel sheet 2 cannot be ensured to be flat over the entire surface, and a strain such as undulation may occur in the width direction and/or the longitudinal direction. In the case where the steel plate 2 is largely deformed, there is a risk that the print head 10 cannot cope with the deformation or that the quality of the formed print is degraded. Therefore, when it is detected that a large strain is generated in the steel plate 2, it is preferable to stop printing on the steel plate 2 and pass the printing portion B.

The strain detection unit F is configured by disposing a plurality of distance detection members 29 at predetermined intervals on a frame 28 provided across the conveyor 1. The distance detection members 29 utilize laser sensors, and are mounted to the frame 28 so as to be set to the same height H as each other in the vertical direction of the conveyor 1. The interval between the adjacent distance detection members 29 is not particularly limited, and is preferably set as appropriate in accordance with a preset maximum width dimension of the steel plate 2 and an assumed strain.

The steel sheet 2 is conveyed by a conveyor 1 driven at a predetermined speed. However, there is a risk of slippage occurring between the steel sheet 2 and the conveyor 1, and the driving speed of the conveyor 1 may not coincide with the speed at which the steel sheet 2 is actually conveyed. In this case, the printing performed on the steel plate 2 may be deviated from the target position. Therefore, it is necessary to detect the actual conveyance speed of the steel plate 2 and drive the print head 10 in accordance with the detected conveyance speed.

The conveyance speed detection unit G detects the actual conveyance speed of the steel sheet 2, and is disposed upstream of the printing unit B in the conveyance direction of the conveyor 1 and substantially at the center of the conveyor 1 in the width direction. The conveyance speed detection unit G includes: a rotating body 31 that rotates in contact with the surface of the steel sheet 2 being conveyed as the steel sheet 2 is conveyed; and a pressing member 32 that is supported by the frame 28 and presses the rotating body 31 against the surface of the steel plate 2.

The conveyance speed of the steel sheet 2 can be detected by detecting the rotation of the rotating body 31 using a rotary encoder, not shown. In particular, the rotating body 31 is pressed against the surface of the steel plate 2 with a substantially constant force by the pressing member 32. Therefore, even when the steel plate 2 has irregularities in the longitudinal direction thereof without causing a slip between the rotating body 31 and the surface of the steel plate 2, the irregularities can be met, and the accurate conveyance speed of the steel plate 2 can be detected.

In the present embodiment, the rotating body 31 is configured to rotate along with the conveyance of the steel plate 2 by contacting the upper surface of the steel plate 2. However, the surface to be contacted by the rotating body 31 is not limited to the upper surface of the steel plate 2, and may be the lower surface or the side surface.

The control unit 35 includes: a print data storage unit 35a that stores print data input from the input device 36; a program storage unit 35B that stores operation programs of a printing unit B, an inclination detection unit C, a thickness detection unit D, a both-end height detection unit E, a strain detection unit F, and a conveyance speed detection unit G that constitute the printing apparatus a; and a calculation unit 35 c.

The print data storage unit 35a inputs specification information such as a thickness, a length, and a length of the target steel plate 2 and print information to be printed from the input device 36 in advance, and stores the specification information and the print data. The program storage unit 35B stores in advance an operation program for each of the sections B to G with respect to the steel plate 2 supplied from the upstream side of the conveyor 1.

Next, printing on the steel plate 2 by the printing apparatus a configured as described above will be described.

The steel plate 2 is supplied from the upstream side of the conveyor 1, and when the specification information of the steel plate 2 is transmitted or input to the control section 35 from, for example, a blasting device disposed on the upstream side of the conveyor 1, the specification data and the print data set for the steel plate 2 are read.

When the longitudinal downstream end 2a of the steel plate 2 conveyed by the conveyor 1 is detected by the longitudinal end detecting means 18 of the inclination detecting portion C, the distance to the width-direction end face 2C of the steel plate 2 is detected by the width-direction end face detecting means 19a and 19b and sent to the control portion 35. The controller 35 calculates the inclination of the steel plate 2 based on the difference between the distances to the end face 2c detected by the respective widthwise end face detection means 19a and 19b, and converts the coordinates of the stored print data based on the calculation result.

The detection of the longitudinal end 2a of the steel plate 2 by the longitudinal end detecting means 18 is performed simultaneously with the detection of the distance to the surface of the steel plate 2 by the thickness detecting means 20 of the thickness detecting section D, and the detected distance h is sent to the control section 35. The control unit 35 compares the thickness t of the steel plate 2 obtained from the height H of the thickness detection means 20 from the conveyor 1 and the detected distance H with the specification data of the steel plate 2 stored in advance, and determines that the steel plate is the target steel plate if the difference between the two is within the allowable range.

When it is determined that the supplied steel sheet 2 is a target steel sheet to be printed, the both-end-side height detecting section E, the strain detecting section F, the conveyance speed detecting section G, and the printing section B, which are located downstream in the conveyance direction, are controlled in accordance with a predetermined operation program. At this time, the height to separate the printing head 10 from the surface of the steel plate 2 is designated to the elevating motor 14a of the elevating carriage 14 of the printing section B.

When the thickness of the steel sheet 2 deviates from the specification data stored in advance, it is determined that the supplied steel sheet 2 is not the target steel sheet, and the steel sheet passes through the both end side height detecting section E, the strain detecting section F, the conveyance speed detecting section G, and the printing section B, which are located downstream in the conveyance direction, without being a printing target.

When the steel plate 2 conveyed by the conveyor 1 is a printing target, the drive motors 26a and 26b of the both-end-side height detection section E are rotated based on a command from the control section 35, and the arms 25a and 25b are successively dispatched in the direction crossing the conveyor 1. The distance detection members 23a, 23b are opposed to the vicinity of the widthwise ends 2b1, 2b2 of the steel plate 2 by the successive dispatch of the arms 25a, 25 b.

Then, the heights hb1 and hb2 near both ends in the width direction of the steel plate 2 are detected by the distance detection members 23a and 23b and sent to the controller 35. The heights hb1, hb2 near both ends in the width direction of the steel plate 2 detected by the distance detection members 23a, 23b are compared with the thickness of the steel plate 2 detected by the thickness detection unit D by the control unit 35.

When a difference occurs between the two, if the difference is within the allowable range, the lifting motor 14a of the printing unit B corrects the value of the height of the printing head 10 from the surface of the steel plate 2 based on the difference. When the difference between the two values deviates from the allowable range, it is determined that printing cannot be performed on the steel sheet 2 and the steel sheet passes through the subsequent strain detection section F, conveyance speed detection section G, and printing section B.

When the steel plate 2 to be printed, which is conveyed by the conveyor 1, reaches the strain detection section F, the distances to the surface of the steel plate 2 are simultaneously detected by the plurality of distance detection means 29 disposed in the strain detection section F and sent to the control section 35. The control unit 35 compares the distances from the distance detection members 29 to detect the deformation in the width direction of the steel sheet 2, that is, the state of the unevenness. Then, when the state of the distortion is within the allowable range, the lifting motor 14a of the printing section B corrects the value of the height of the printing head 10 from the surface of the steel plate 2 based on the distortion. When the difference between the two is outside the allowable range, it is determined that printing on the steel sheet 2 cannot be performed and the steel sheet passes through the subsequent strain detection section F, conveyance speed detection section G, and printing section B.

When the steel plate 2 to be printed, which is conveyed by the conveyor 1, reaches the conveyance speed detection section G, the rotating body 31 is pressed against the surface of the steel plate 2 by the pressing member 32, and the rotating body 31 rotates along with the conveyance of the steel plate 2. The rotation of the rotating body 31 is detected by a rotary encoder built in or connected to the rotating body 31 and sent to the control unit 35, and the control unit 35 detects an accurate conveying speed of the steel sheet 2. Then, based on the detected accurate conveyance speed of the steel sheet 2, the drive motors 12a and 13a of the first and second carriages 12 and 13 of the printing section B are controlled to be driven.

The control unit 35 sets the height of the print head 10 based on the thickness of the steel plate 2 detected by the thickness detection unit D, converts the coordinates of the print data in accordance with the inclination of the steel plate 2 detected by the inclination detection unit C, and then sets the speeds of the first carriage 12 and the second carriage 13 based on the accurate conveyance speed of the steel plate 2 detected by the conveyance speed detection unit G to drive the first carriage 12 and the second carriage 13, respectively, thereby performing the target printing on the steel plate 2. Further, by correcting the height of the print head 10 based on the difference in height detected by the both-end-side height detecting section E and the strain detecting section F, sharp printing can be performed.

Industrial applicability

The printing apparatus of the present invention is not limited to the one that is advantageously used when printing on a steel plate, but is advantageously used when printing on a plate-like material conveyed by a conveyor.

Description of reference numerals:

a printing device

B printing part

C inclination detection unit

D thickness detection part

E both end side height detecting section

F strain detection unit

G conveying speed detection part

1 conveyor

2 Steel plate

2a end part

2b1, 262 near both ends in the width direction

2c end face

10 print head

11 Beam section

12 first carriage

12a first carriage drive motor

13 second carriage

13a second carriage drive motor

14 lifting bracket

14a lifting motor

18 longitudinal end detection member

19a, 19b width direction end face detection member

20 thickness detection member

23a, 23b distance detecting member

24 stand

25a, 25b arm

26a, 26b drive motor

28 frame

29 distance detecting member

31 rotating body

32 pressing member

35 control part

35a print data storage unit

35b program storage section

35c arithmetic unit

36 input device.