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The second Tokyo Olympic and Paralympic Games will be held in 2021. The previous Olympic Games were held in Showa 39 (1964).<\/p>\n
Deep in my ears, the song \u201cTokyo Olympics Ondo,\u201d sung by the late Haruo Sanba, still lingers.<\/p>\n
Looking back, this was precisely the period when on-site joints in steel structures were transitioning from \u201crivets\u201d to \u201chigh-strength bolts.\u201d Consequently, since the route of the first phase of the current Metropolitan Expressway was constructed in preparation for the Olympics, rivets were used for the on-site joints of most of its bridges and steel piers.<\/p>\n
If you look up from beneath a highway, you can see rows of rivet heads at the joints. The workers who set these rivets are commonly called \u201criveters,\u201d and the term is written in kanji as \u201c\u9278\u92f2\u5de5.\u201d<\/p>\n
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The riveting work was extremely grueling.<\/p>\n
Since we\u2019re handling rivets heated to 900\u20131,100\u00b0C, even the slightest mistake could result in severe burns\u2014or, depending on where the rivet strikes, could even be fatal.<\/p>\n
In addition, since this involves on-site welding work at steel bridge construction sites\u2014and the work is performed at heights ranging from tens of meters to over 100 meters above ground level\u2014there is also a risk of falling.<\/p>\n
The same applies to steel frame construction.<\/p>\n
To perform the riveting process, you must first heat the cold (room-temperature) rivet to approximately 1100\u00b0C, which is the optimal temperature for riveting.<\/p>\n
On site, the top of a steel drum is typically cut off, and a firebox is set up at about one-third of its height. Coke is burned here to heat about 10 rivets arranged in a row. This furnace is called a \u201chozo\u201d or \u201choto.\u201d<\/p>\n
Incidentally, \u201choto\u201d is written with the kanji for \u201cyin\u201d and refers to the female genitalia. It is believed that \u201choto\u201d was corrupted into \u201chozo,\u201d and is distinct from the \u201chozo\u201d in the phrase \u201cto bite one\u2019s navel.\u201d<\/p>\n
The temperature is around 1,000\u00b0C when the rivets forged on this anvil turn a cherry blossom pink, so the craftsman picks them up with a pair of fire tongs about 1 meter long and, with exquisite control, tosses them to the exact spot where they\u2019ll be riveted into the joint. It\u2019s a truly magnificent sight.<\/p>\n
The operator catches it using a funnel-shaped receptacle with a slightly larger handle, removes any scale from the surface, and inserts it into the rivet hole to be fastened using a pair of fire tongs.<\/p>\n
Next, the end with the head is held in place on the anvil, and the operator holding the rivet hammer strikes the rod-shaped shank with the hammer until a hemispherical head is formed. Since the rivet is hot throughout, the impact causes it to expand and fill the entire joint hole.<\/p>\n
The rivet hammer (commonly known as a \u201cgun\u201d) that was generally used on construction sites works by using compressed air to drive a piston back and forth inside a cylinder, and the resulting impact is used to drive the rivet into place.<\/p>\n
There was a snap attached to the muzzle of the gun, which the piston would strike. Since the snap was only inserted a few centimeters into the tip of the cylinder, it would have been pushed out by the piston and flown off somewhere if left as is. For that reason, it was secured to the body of the gun with a thick piece of wire.<\/p>\n
At least five people are needed\u2014a rivet setter (who is the foreman or \u201cboshins\u201d), a receiver, a guide plate operator, a striker, and a bolt remover\u2014but generally, a team of 5 to 7 people would work together.<\/p>\n
\"Roofer's won't come out if even a single drop of rain falls in the morning,\" the scaffolders used to say.<\/p>\n
It\u2019s true that if it starts raining while the riveting work is in progress, rain can seep in through the gaps in the base material where the rivets have been driven, which could cause the rivets themselves to loosen.<\/p>\n
It would be unbearable to have to redo all that hard work after putting so much effort into it, so if it starts to rain, we\u2019ll stop the riveting work immediately.<\/p>\n
Also, as Mr. Tobi says, if it\u2019s drizzling around 6 or 7 in the morning, we don\u2019t go out to the job site. So, when the sun starts to peek through around 8:00 a.m., it\u2019s a real headache\u2014we get relentless pressure from the site supervisor and the general contractor (GC) to get to work quickly. This pressure escalates rapidly, especially if the project is behind schedule.<\/p>\n
As part of a major renovation project at a Japan National Railways (JNR) station (at the time), construction work was carried out on both the bridge and the steel framework.<\/p>\n
So, as mentioned earlier, it had been drizzling since morning, and the riveters hadn\u2019t shown up. At that time, the riveting foreman and the former blacksmith foreman\u2014who was acting as the company\u2019s manager\u2014were in the office, and there was also a young man who served as both an office clerk and a cleanup crew member on site, so we decided the four of us would handle the riveting.<\/p>\n
The master riveter uses his years of experience to heat the rivets. However, since he can\u2019t quite get the hang of throwing them anymore, a young worker goes up to the tenon, takes the heated rivet, carries it along the scaffolding to the joint, and inserts it into the rivet hole.<\/p>\n
My job was to hold the anvil, and the blacksmith\u2019s master was in charge of striking it. We figured that as long as we made the right sounds, everyone would be satisfied, so we pretended to rivet the pieces together, but after about an hour, we were all completely exhausted.<\/p>\n
Before long, a light drizzle began to fall from the overcast sky, so I took that as my cue to call it a day. Never before\u2014or since\u2014have I felt so tense or had my muscles get so stiff on a construction site.<\/p>\n
The next day, I got a thorough scolding from the professional riveter, who said, \u201cWhy did you go and do something unnecessary like this? It just creates more work for me!\u201d And that was the end of my amateur riveting attempt.<\/p>\n
(To be continued)<\/p>\n
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From the God of Construction<\/p>\n
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The Rivet Maker and \u201cTokyo Olympics Ondo\u201d The second Tokyo Olympic and Paralympic Games will be held in 2021. The last Olympics were held in Showa 39 (1964). The song \u201cTokyo Olympics Ondo,\u201d sung by the late Haruo Sanba, still lingers in the back of my mind. Let me think back\u2026<\/p>","protected":false},"author":2,"featured_media":39421,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[1231],"tags":[1246],"class_list":["post-44369","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-1231","tag-1246"],"acf":[],"yoast_head":"\n