Post-press binding common method--strap line setting (2)

2. Interlocking locks. The book block after staggered locking is shown in Figure 4-4. The staggered flat lock is a kind of special lock stitch mode of the flat lock. The position of the two adjacent placards in the book block is different, and the position of the split ties is the same, so that the yarns serially connected in the signature can be evenly distributed. It is distributed at the folds of the booklet, so that the thickness of the book's back and the book block can be kept basically the same, and the bound book is relatively flat. Therefore, when the paper is thin or the yarn is thick, staggered flat locks are required in order to avoid protruding or excessively protruding projections at the back of the book.

Figure 4-4 Staggered lock

The work principle of the staggered flat lock is basically the same as that of the ordinary flat lock, except that two threading needles, two threading claws and a hook wire needle constitute a group to complete the lock thread process, as shown in Figure 4-5.

Figure 4-5 staggered flat lock punching and threading process

1- Left threading needle 2 - Left hook 3 - Base pin 4 - Yarn 5 - Right hook 6 - Hook pin
7- Right threading needle

When the first poster line is locked, as shown in a1b1c1d1e1 in Figure 4-5, after punching and threading, the left knuckle starts to move to the right, and the yarn introduced by the left threader is pulled to the hook needle 6. After that, the right window needle and the right finger 5 do not act. In the second poster line, as shown in a2b2c2d2 in Fig. 4-5, after punching and threading, the right finger 5 moves to the left, and the yarn introduced by the right needle 7 is pulled onto the hook needle. , then reset.

Figure 4-6 Sketch of cross lock book block

3. Cross lock. Cross locks are also called jump locks. In the book block, the position of each placard is different, that is, odd and double numbers are alternately locked, as shown in Figure 4-6. Using this kind of lock line method can not only make the gutters evenly distributed, but also can be woven with a gauze tape to make the books solid and beautiful.

The principle of cross lock and staggered flat lock is basically the same. The only difference is that between two fixed threading needles, there is an active threading needle, which can be used for left and right reciprocating motions, threading the yarn into the pages of each book, thus Interlocked into a book. The cross-lock lock speed is slow, generally 60 posts/min, while the flat lock is usually up to 70 to 80 posts/min, and it is easy to operate. Therefore, flat lock is the most widely used binding method in sewing.

(to be continued)