1、14FTM07 AGMA Technical Paper A Case Study in a Practical Application of Smart Gearbox Technology By A.J. Soder, Sumitomo Drive Technologies 2 14FTM07 A Case Study in a Practical Application of Smart Gearbox Technology Adam J. Soder, Sumitomo Drive Technologies The statements and opinions contained h
2、erein are those of the author and should not be construed as an official action or opinion of the American Gear Manufacturers Association. Abstract In many different industries, the gearbox is a very critical component in each individual operation. Regardless of what the specific application is, fro
3、m coal mining to moving an airline travelers baggage, the conveyors rely on the gearboxes to convert speed and torque into motion. In this day and age where technology is being used to make our lives easier in many different aspects, the power transmission industry seems to be lagging behind in this
4、 trend. The gearbox in its simplest form has not seen many technological changes in the last 20 years. Many end-users rely heavily on the gearboxes in their applications. They also want it to last as long as possible, but still pay a minimal cost for the same product and lifespan. However, without p
5、roper maintenance, regardless of the gearbox design, the useable life of the gearbox could be significantly shorter than desired. In some cases, the end-users fully understand that maintenance is a requirement for long life of the equipment. They just do not have: a) adequate staffing in their maint
6、enance departments; b) the funds to support a maintenance program; or c) the time to devote to maintenance. Copyright 2014 American Gear Manufacturers Association 1001 N. Fairfax Street, Suite 500 Alexandria, Virginia 22314 October 2014 ISBN: 978-1-61481-099-5 3 14FTM07 A Case Study in a Practical A
7、pplication of Smart Gearbox Technology Adam J. Soder, Sumitomo Drive Technologies Introduction In many different industries, the gearbox is a very critical component in each individual operation. Regardless of what the specific application is, from coal mining to moving an airline travelers baggage,
8、 the conveyors rely on the gearboxes to convert speed and torque into motion. In this day and age where technology is being used to make our lives easier in many different aspects, the power transmission industry seems to be lagging behind in this trend. The gearbox in its simplest form has not seen
9、 many technological changes in the last 20 years. Many end-users rely heavily on the gearboxes in their applications. They also want it to last as long as possible, but still pay a minimal cost for the same product and lifespan. However, without proper maintenance, regardless of the gearbox design,
10、the useable life of the gearbox could be significantly shorter than desired. In some cases, the end-users fully understand that maintenance is a requirement for long life of the equipment. They just do not have: a) Adequate staffing in their maintenance departments; b) The funds to support a mainten
11、ance program, or c) The time to devote to maintenance. This provides a new opportunity to develop gearbox technology that essentially advises when the maintenance is needed and can help get the most life possible out of the reducer. This “smart gearbox” technology will provide a system that alerts u
12、sers as to when a gearbox could potentially be failing could be the next major technological advance in power transmission. It allows users to essentially put a status on reducers condition, and could use real-time data instead of the many varying opinions of many maintenance technicians to determin
13、e how the gearbox is operating. The concept of condition monitoring gearboxes is not necessarily and new concept. There are many different “Off the shelf” systems that are available in the market today. However, due to the uniqueness of the Sumitomo Cyclo Reducer (Figure 1), the concepts previously
14、used for standard, involute gearing do not apply. The eccentric cam and Cyclo disc arrangement is inherently imbalanced by design. The design incorporates ways to minimize the imbalance but they are used for more industrial applications versus precision applications. There will always be some imbala
15、nce, which manifests itself as vibration. Figure 1. Cyclo Speed Reducer 4 14FTM07 The facility used for this case study, has a very large installed base of Sumitomo Cyclo based products at around 300 units. Of the 300, there are roughly 20 “unique” units that are the same Cyclo frame size. Each one
16、of these, are installed in applications that vary greatly in regards to loading criteria, run time, duty cycle, etc. Although all of the reducers are of the same cycloidal design, all of the factors that affect the vibration and temperature measurements of a gearbox vary greatly between each unit. T
17、his fact is what makes creating a monitoring system for the Cyclo reducer a difficult task. The purpose of the paper is to discuss the development of this technology using real-world application testing and data analysis, while keeping in mind the needs of the end-user in order to assist them in dev
18、eloping their monitoring system. It will describe the previous maintenance methodologies used and how the ever-changing needs of the industry require them to introduce a proactive maintenance system rather than a typically reactive approach. It will explain the testing performed at the users facilit
19、y which helps gather the data that cannot be duplicated on a test system (Figure 2). It will then explain how after all the data is reviewed and analyzed, how it is then relayed back to the user so it can be implemented by their maintenance departments. It will discuss reviewing the data of a failed
20、 gearbox during testing and how looking at the data can give a glimpse of how to understand what the data is telling us in regards to the end goal of the project. Background In years past, the need for maintenance of mechanical systems has not changed very much. No matter how expensive or inexpensiv
21、e the equipment is, maintenance is something that cannot be avoided. The end-user in this case study sorts packages in the material handling industry, and down time is critical. Spanning the U.S and many other countries, they have many gearboxes that need maintenance of some kind. In the case of the
22、 gearbox, we normally focus on lubrication and how it should be changed periodically depending on how severe the loading conditions are in the application. In the past, maintenance methods consisted of a set schedule for changing the gearbox oil. The schedule was set that every six (6) months, regar
23、dless of age of the unit, all gearboxes are drained, and the units be refilled with new lubricant. From a gearbox manufacturers standpoint, this methodology is one of the best ways to get the longest life out of the unit. The lubrication generally is the first item of the gearbox assembly that will
24、start to break down and fail. Once the lubrications starts failing, it can no longer lubricate the rolling components of the gearbox. This causes an increase in friction, which leads to an unwanted temperature rise, ultimately leading to the failure of the gearbox. Therefore, having new lubrication
25、inside the unit as much as possible will help its lifespan immensely. Figure 2. Test unit 5 14FTM07 From the end-user viewpoint, this methodology can take a large amount of resources, and become very expensive over the life of the gearbox. It can also be environmentally unfriendly if a facility is t
26、rying to “go green”. Most larger facilities have hundreds if not thousands of gearboxes located throughout the facility. There are not enough maintenance technicians to perform the required oil replenishment. The equipment must be shut down, and the longer it is shutdown, the less profits are there
27、to be made. With the recent growth of the parcel handling industry, shutting down for maintenance will hinder the chances of meeting the goals that have to be met and they cannot be achieved while the equipment is shut down. This type of maintenance methodology can also be perceived as an unneeded e
28、xpense. The lubrication being changed in some of the gearboxes may not have been needed to be changed. The gearbox could have been installed with new oil only a month prior to the scheduled oil change and therefor they would be throwing away perfectly good oil. In real world applications, depending
29、on the specific application the unit is operating in, the oil life can vary. On a scale of 1 to 100%, after a certain length of time, the gearboxes in some applications may have only used 50% of the lubrications life, whereas others may have only used 15% or 75%. Therefore, the units with lower oil
30、usage life do not have to be changed, whereas the longer life units should have the lubrication changed. Currently, the end-user has concluded that their most cost effective maintenance method is a “run to fail” methodology. As stated previously, many of the users facilities do not have the quantity
31、 of maintenance technicians needed to perform all the required maintenance on the gearboxes. Knowing this information, it was decided to not perform any sort of maintenance to the equipment. The large costs incurred of using a semi-annual preventative maintenance plan outweighed the benefits to the
32、user. It can be said that this method is the more “financially friendly” solution. Since no maintenance is performed throughout its life, there are no costs associated with the gearboxes, other than their original purchase and installation costs, which cannot be avoided (Figure 3). This cost savings
33、 is only short-term. There will come a time in the life of the gearbox that it will no longer be able to perform as it was originally intended. The lubrication that was in the gearbox since installation will be the limiting factor in how long of a service life the gearbox will have. At a certain tim
34、e, the lubrication will fail, and the entire gearbox will follow suit. When this occurs, it is normally unexpected and unplanned. When a failure is unplanned, it leads to down time that is expensive to any industry, and having to purchase/install the replacement gearbox only adds to the overall cost
35、 in both time and money (Figure 4). Based on the experiences with run to failure, there was a major push to come up with a new method for maintaining the gearboxes. A method in which allows for the most life out of the product, without having any unnecessary costs throughout its lifespan. Figure 3.
36、Cost comparison 6 14FTM07 Figure 4. Productivity Levels with unplanned downtime Table 1 is an example of the cost associated with the three maintenance strategies discussed: regular maintenance; run-to-fail; and condition based maintenance (condition monitoring). The assumed figures shown are only f
37、or one gearbox in operation. Many user facilities have large quantities in operation at any time. As we can see, by only performing maintenance when the data deems it necessary, there is a potential for a great cost savings for larger facilities with large quantities of gearboxes. The underlying goa
38、l of the project was to come up with a way to be able to predict, based on actual data, when a gearbox has the potential for failure during operation. In order to do this, a monitoring system must be created that, based on certain trigger points, alerts a user to any potential problem, up to and inc
39、luding the failure of the unit. The idea being, once the data reaches that specific point, the end-user would be able to schedule maintenance with a degree of certainty of how severe the issue is, and how urgently any maintenance work must be performed. Downtime cannot be avoided 100%, but with this
40、 technology, users would be able to schedule any downtime to a schedule that better suits their operation. Whether it is in between shifts, or a lower volume day, the downtime now becomes a part of a fully predictable and to a set plan. It becomes aligned with the set schedule that has been proven p
41、rofitable for the customer (Figure 5). Table 1. Cost of ownership Associated cost/Strategy Regular maintenance Run-to-fail Condition based Unit cost $1000 $1000 $1500 Installation $1000 $1000 $1000Unit maintenance (over life of unit) $15,0001)$0 $02)Life of unit 5+ years 3 years 5+ years Total inves
42、tment $17,000 $52,0003)$25004)NOTES: 1)Assumes $500 per oil change (Labor, Materials, etc.) 30 oil changes over the course of five (5) years (two per year). Maintenance performed regardless of the condition of the unit. 2)$0 maintenance cost assumes there are no signs of pending failure based on the
43、 data recorded on the monitoring system. Only required maintenance is performed. 3)Assuming $50,000 profit loss due to the downtime suffered during the time when the unit failed in operation. 4)Additional cost would only come if the data proved that maintenance was required. Figure 5. Productivity l
44、evels when maintenance is aligned 7 14FTM07 Using this methodology allows the proper time to gather all necessary items to make a repair. It allows the technicians to be able to safely perform any maintenance without the risk of being around any rotating equipment that is in full operation. It has l
45、ess profit-loss due to being able to plan the maintenance around when the users system is not in full production and making profit. Field testing In order to gather the most accurate data, it was preferred that field-testing be performed at the users facility. The other option would have been perfor
46、ming the tests in the research and development (R&D) of our manufacturing headquarters. This option was not selected. In the past, we have not been able to mimic their exact use conditions. Testing in their environment allows for 100% accurate data points, so we can fully understand all aspects of t
47、heir operation. When it comes to testing gearboxes, there are key items that need to be recorded that give an indication as to the current condition of the unit. For all of the testing, we recorded the following parameters for installed gearboxes: 1. Gearbox vibration 2. Gearbox temperature 3. Ambie
48、nt temperature 4. Motor amperage 5. Motor frequency These parameters were selected based on our previous testing experience and knowledge of the test application. The vibration of the gearbox was recorded on the fastest rotating component of our product offering, the Cyclo portion. In the case of te
49、st parameters, the products used by the customer use the Cyclo as the first stage of reduction. In all cases, the Cyclo (Figure 6) is the only portion of the gearbox that sees full input speed of the motor (1800 RPM for all testing). With this high speed will come greater friction between reduction components and higher levels of vibration. Therefore, the vibration and temperature levels were recorded at this location on the gearbox also. Ambient temperature was recorded in order to establish a temperature rise of the units. Unit Temp. Ambient Temp.T (1) The motor ampera
