Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)51

Advanced Production Lines for Turbochargers

MASATO KINOUCHI*1

YOSHIYUKI MIYOSHI*1

KOUICHI YAMATO*2

YOSHIKI KON*2

DAIKI WATANABE*2

NAOHIRO UCHIDA*2

In order to cope with the sharp increase in the demand for turbochargers, Mitsubishi HeavyIndustries Engine & Turbocharger, Ltd. (MHIET) is pushing forward with the transition of theSagamihara District Third Plant to a smart factory through the further automatization of facilities
and the use of IoT technologies toward the realization of an advanced turbocharger production
line. In the present situation, the automatization of the major processes on the production line has
been achieved, but for carrying in parts, appearance inspection, equipment operation monitoring,etc., the work is conducted by hand. This report introduces the efforts to develop the component
technologies for automatization toward the realization of an advanced production line: (1) theautomatization of the carrying in/carrying out of parts with a camera-equipped robot designed tooperate autonomously; (2) the automatization of appearance inspection; and (3) the establishmentof a smart factory using IoT technologies.

|1. Introduction
In recent years, the demand for turbochargers has been rapidly increasing with thebackground of the expansion of automobile emission controls and the downsizing of engines. At
our Sagamihara District Third Plant, the further enhancement of productivity and increase in theefficiency of production for the turbocharger production line has been an urgent need.

Figure 1

Turbocharger production line and the status of automation

So far, in the turbocharger production line, as shown in Figure 1, automatization has beenachieved for machining, assembly and dimension/performance inspection, which are the mainprocesses for core parts, and an automatization rate of 80% to 90% for the entire line (the numberof automation processes/the number of all processes) has been realized. However, the work in theprocesses of carrying in parts, appearance inspection, equipment operation monitoring, information*1*2

Chief Staff Manager, Tuabocharger Division, Mitsubishi Heavy Industries Engine & Turbocharger, Ltd.
Tuabocharger Division, Mitsubishi Heavy Industries Engine & Turbocharger, Ltd.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)52

collection, etc., which make up the remaining 10% or so of the line, is conducted by hand. Theseprocesses should be automatized and the amount of labor necessary should be reduced.
Accordingly, we have been making efforts for (1) the automatization of the carrying
in/carrying out of parts with a camera-mounted robot designed to operate autonomously; (2) theautomatization of appearance inspection; and (3) development toward a smart factory using IoTtechnologies, in order to promote the further automatization of facilities and information toward therealization of an advanced turbocharger production line. In this report, the efforts in three caseexamples are introduced.

|2. Automation of carrying in/carrying out of parts
2.1

PurposeAt present, the work for carrying in parts to each line and carrying out finished products isconducted by hand. If automatization is simply promoted, one robot can be placed at the head andthe rear of each line, respectively, to perform the carrying in/carrying out of parts, but the initialcost becomes high. Accordingly, we are aiming at automating the carrying in/carrying out of partsat multiple locations using an Automatic Guided Vehicle (AGV) with a robot on board, as shownin Figure 2. As the first step in this effort, a manually operated carriage with a robot on board wasdeveloped as a prototype AGV, and the component verification for the interlocking/merging
technologies of the robot control and carriage functions was conducted as described below.

Figure 2 Concept of automatic carrying in/carrying out of parts by robot-equipped AGV

2.2

Outline of the developed robot carriage

The outline of the developed robot carriage is shown in Figure 3. At the tip of thecarriage-mounted, six-axis articulated arm robot, three kinds of hands corresponding to the shapesof objects can be installed by an automatic changer. For the detection of a workpiece, a 2D camera
is mounted at the tip of the robot and a laser displacement gauge is added so that three-dimensional
information can be acquired for higher precision and safety. In addition, docking with the location
for carrying in or carrying out parts (hereinafter referred to as a station) is realized by an automatic
clamping structure with an air cylinder. The carriage also has utility connectors for receiving
electricity, air and signals so that it can be automatically connected with utilities concurrently withthe docking of the carriage and station. With this configuration, no power is supplied to the robot
when the carriage is moving, and there is no danger of a malfunction of the robot occurring while it
is moving. On the other hand, as a safety measure during the operation of the robot at a station, theoperation area is surrounded by a safety fence, securing a safety area only on the robot access sidewith the safety scanner.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)53

Figure 3 Configuration of robot carriage

2.3
(1)

Operation verification
Basic operation
Dedicated stations for the carrying-in side and the carrying-out side were manufactured
to examine the connection of utilities by docking, and verification for the detection of aworkpiece, the positioning of the robot and picking and release operations at each station wereconducted. As a result, a series of operations could be performed without problem. Concerning
the automatic hand changing operation, the handling operation of the partition plate in thereturnable box, which is an object other than a workpiece, was also checked, and it wasconfirmed that there was no problem in the basic operation. (See Figure 4.)

Figure 4 Verification of basic operation(2)

Correction of position/attitude of the robot in an indefinite state
Generally, an AGV has a positioning precision of several millimeters, and an inclinationis also caused depending on the floor surface condition. Although the robot carriage has adocking mechanism that uses a clamp and the area error can be minimized, relativeMitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)54

displacement of the robot-equipped AGV and a workpiece at the station always occurs. As
such, a correction function was provided, by which three-dimensional coordinates of markingsfor the correction of the positions of three predetermined points were detected by the robot andalignment was performed, as shown in Figure 5. To check the effect of the floor surface, withshims of several millimeters being put under the wheels of the carriage to force an error, thecorrection operation and the subsequent picking operation were examined. As a result, thecarriage operated without problem.(3) Safety function
As for the safety function during docking with a station, tests for the detection of theoperator and obstacles by the safety scanner and the operation of the robot slowdown/stop
function were conducted, and it was confirmed that the safety function at the time when theoperator and the robot share the space worked without problem.

Figure 5 Marking for position adjustment and scene of adjustment operation

2.4

In the future

We introduced the aforementioned efforts toward the acquisition of basic technologies(interlocking/merging technologies of the robot control and carriage) for carrying in parts by AGV
with a robot on board. Toward the future, we are planning to realize an AGV with a robot on board
and to promote and complete the automatization of the system for carrying in/carrying out parts
through a number of verification tests in the future. In conjunction with the smart factory that will
be introduced in Chapter 4, efficiency and labor saving in production will also be enhanced.

|3. Automation of appearance inspection
3.1

Purpose of automatic inspection

At present, appearance inspection is conducted visually by operators, which causes problems
such as an increase in the burden on operators due to the increase in the number of units, risk ofoverlooking (outflow of defects) associated with the increase in the burden on operator’s andunevenness in inspection quality due to personal differences. In addition, such inspection results are
not retained as data, and it is difficult to guarantee the quality after shipment. We have beendeveloping a device for automatically inspecting all units in the line. In this chapter, our efforts
toward its realization are introduced.

3.2

Target inspections and prior verification by the component tester

With consideration given to the frequency of the occurrence of defects, the effects on quality
and performance, etc., inspections for blowholes on the processing surface of bearing housings(B/H) and for blade shape (blade bending) of compressor wheels (C/W) were selected as theinspections to be automated as shown in Table 1. For blowholes, the hole inner face and the upper,
lower and side faces (six faces) on the hole circumference were inspected.
For a prior verification, a component tester was manufactured, and the selection andinstallation of measurement instruments, the adjustment and optimization of the parameters for theinstruments, etc., were conducted. (See Figure 6.) This prior verification is an important process inorder to obtain a reliable effect after the device is introduced in the production field. As a result of
the component verification, the prospect of realizing automatic detection for two kinds ofinspections for the hole inner face and circumference was obtained, and the devices were developedand in-lining was realized as described in Section 3.3.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)55

Table 1 Objects to be inspected and inspection methods
Name of part
Inspecting item

Bearing housing
Blowhole

Inspecting portion

Hole inner face

Bearing housing
Blowhole
Upper and lower side faces ofthe circumference (six faces)

Compressor wheel
Blade bending
Blade portion

Appearance

Detectable size

Approximately 1 mm

Approximately 1 mm

Inspection method

Change of amount of laser lightreflected

CCD camera + image processing―

Dome light, ring light

Approximately 0.5 mm
Three-dimensional
measurement by laser
displacement gauge―

Completed

Completed

Under verification

Lighting
Instrumentation/in-lining

Figure 63.3
(1)Element test and example of verification results

Developed automatic inspection devices and operation states

Inspection device for hole inner face
The configuration of the inspection device for the hole inner face and the state ofmeasurement are shown in Figure 7(a)(b). While the rotating probe of the inspection device(Sigma Corporation: SG-LSDC) is rotated and translated at high speed, the hole inner wall isirradiated and scanned with a laser beam from the probe tip, and the reflected light is analyzed
for the detection of blowholes. The detection results are shown in Figure 7(c). The state of thecylindrical inner face is output like a development plan. The parameters are set so that a minuteblowhole section (about 1 mm) can be accurately detected. This device has already been
introduced and is operated on the production line at the Third Plant.
(2) Inspection device for circumference of hole
The configuration of the circumference inspection device and the detection results areshown in Figure 8(a)(b). The inspection device has a two-station configuration in which two
kinds of lighting are used properly by the shape of the face to be inspected while the target
workpiece is moved from left to right. Imaging, image processing and defect detection areperformed for each face to be measured. For defect detection, the pixel density difference isused as the evaluation value to perform the threshold determination. In the actual introduction
to the line, a defective sample that imitates a blowhole within the limitation standard wasprepared, and with this detection level as the standard, a threshold that enables a defect to beaccurately detected was set. (A relatively lower threshold is set, so that a minute defect can bedetected in the state of overdetection.) Thereafter, while a 100-percent automatic inspection
was performed in parallel with the visual appearance inspection on the production line, thethreshold was gradually increased to take the approach where the over detection rate becomes
the target value or less, and adjustment was made so that no defects flow out and overdetection
is minimized. (See Figure 8(c).) This device has already been introduced and is operated on theproduction line.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)
56Figure 7

Hole inner face inspection device

Figure 8Circumference inspection device

3.4

Effects of automatization and the future

Through the introduction of automatic detection, the reliability and stability of quality areincreased, and instead of the double check of target sections that was conducted so far, only one
final check is conducted now. This introduction contributed to the reduction of work load.
In the future, with the continued adoption of new technologies and new methods, theinspection targets will be expanded. In addition, by taking advantage of our being able to design,assemble and commission these devices on our own, we will pursue the development of newdevices at a rapid pace. Furthermore, based on the inspection image data that is being accumulated,
we plan to develop more advanced appearance inspection methods using AI technologies such as
deep learning.

|4. Smart factory using IoT technology
4.1

Purpose of smart factory

In order to cope with various customer needs in the global expansion of business,
multi-variety variable production is increasing, and in the present system, an adequate response isdifficult to make. For adequate actions in consideration of such changes in needs and demand, asystem for automatically collecting information from facilities and using the information inproduction is required. Furthermore, a smart factory is required, where by using the information,
implementing the predictive maintenance of equipment and quality, and increasing the operating
ratio, the throughput of overall production is improved.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)57

Accordingly, toward the establishment of a smart factory being targeted through theautomatic collection of information from facilities and the visualization of the factory, three steps
were set as shown in Figure 9 (a). The system construction schedule was prepared, in which
information is collected from facilities in Step 1, the information is used in Step 2, and the system
is connected with related systems in Step 3. The final system conceptual rendering is shown in
Figure 9(b). In this chapter, the content of the information utilization in Step 2 that has been
constructed as of now is described.

(a) Step chart(b) Conceptual rending

Figure 94.2

Toward the construction of the smart factory being targeted

Construction of network baseIn order to collect information from facilities, the construction of a network is needed, inwhich security measures are important. As shown in Figure 10, the network of the factory wasdivided into several layers for study. As a result, the network configuration for providing avisualized security measures was deployed in the factory. An in-house firewall was provided
between the information system network and the inter-controller network, so that the networks
were designed not to affect each other. Thus, network management including the security measures
can be conducted. For the inter-controller network, an Ethernet/IP and EtherCAT-capable network
was constructed.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)
58

Figure 10 Security measures

4.3

Information collection system

In the collection of information from facilities, there are two patterns in the field network
shown in Figure 10: one pattern is to collect information from independent networks between
facilities and the other pattern is to collect information from one facility alone. When an individualcollecting system is constructed, it is considered that consistent management may becomecomplicated at the time of investigating data, and comparisons between single lines and amonglines become complicated. Accordingly, it was decided that the same tool would be used to collectinformation. In addition, in order to minimize the time required for system construction, thesoftware package shown in Figure 11 (CEC Ltd.: Facteye) was selected and introduced without
any customization.
Since it takes time to deploy on all lines at once, five representative lines from the machining
lines and the assembly lines were selected and a trial introduction was conducted. As a result, thetime from the completion of infrastructure construction to the introduction of the data collection
system could be minimized and the initial verification was completed.

Figure 11Information collection system

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 1 (March 2017)
59

4.4

Future deployment

On the pilot line, the introduction and the demonstration check were conducted for Step 1and part of Step 2 in Figure 9. The situation at a site, which couldn't be understood in detail without
visiting the site can now be understood instantaneously at a desk. By the end of 2016, the network
system will be deployed on all lines so that the situation throughout the factory can be understood
immediately.
In order to make it possible to use the obtained data in predictive diagnosis for equipment
and quality, the introduction of data analysis technology is being studied. Under the present
circumstances, the information of the entire Third Factory can be obtained, although the amount ofdata is small, allowing the information accuracy to be improved. Thus, a system that enables
problems to be prevented before they occur will be constructed.
Furthermore, a system of manufacturing that does not produce waste will be developed bylinking these data with demand information and other systems, and the throughput of the entire
factory will be increased. The smart factory shown in Step 3 of Figure 9 will also be establishedthrough deployment to and conjunction with overseas sites..

|5. Conclusion
In this report, three case examples of development efforts for automatization component
technologies toward the realization of an advanced turbocharger production line were introduced.
With the efforts being continued, we will expand the automation facilities, thereby increasing
reliability and quality. In addition, we aim at maximizing the production yield through theestablishment of a smart factory using IoT technologies.