**4. Stitches of braided lace**

During the formation of lace, the yarns form an X that is identified as either a cross or a twist depending on the direction. Twist is defined as a counter-clockwise motion where the right yarn of each pair is laid over the left yarn. The twist motion pairs stay together on the machine plate. Cross is a clockwise motion worked with two adjacent pairs and the inner pairs are crossed so that the left yarn of the inner pair is laid over the right yarn. The cross pairs are interchanged. In **Figure 2**, the first and fourth yarns remain stationary while the second and third yarns cross multiple times. Then the first and third yarn twists multiple times simultaneously with the second and fourth yarns.

#### **4.1. Barmen lace**

For various reasons details of the Barmen braiding machine have not been readily available, and known only by a select few. The complexity of these machines tended to require specialized operational expertise as well. Thus, expertise with these machines tended to be concentrated within the immediate geographic region of the machine origin. In the case of the Barmen lace braiding machine, the region was Barmen—an industrial city that later merged with Wuppertal, Germany. Publications, outside of textile trade literature and patent literature, related to the Barmen lace braiding machine are scarce. The descriptions found in the patent literature are inadequate for interested audiences outside those skilled in the art. In general, the lace braiding industry had many trade secrets where knowledge of pattern design, machinery, and operations was confined to an esoteric group of practitioners.

**Figure 2.** Basic stitches of lace.

Although this unique nature of the Barmen lace industry had limited the dissemination of widespread knowledge, it did encourage the production of lace in the region. Barmen lace benefitted from the proximity of lace producers, lace machine designers and many technological developments are evident in the U.S. Patents issued to residents of Barmen and Wuppertal, Germany.

The Barmen lace machine is an evolution of the original mechanically geared braiding machine, often known as a Maypole braiding machine. In the Maypole braiding machine, the yarns are divided into two fixed groups of counter rotating directions producing two oppositely pitched sets of helices. The Barmen braiding machine allows individual yarns to change direction at effectively any point along its path. Similarly, as the Maypole braiding machine was inspired by the Maypole dance, the Barmen machine design inspiration comes from the agile hand motions of bobbin lace makers. The distinct advantage of the Barmen over the conventional Maypole braiding machine is found in the motion control of individual yarns. Pattern control in these machines is implemented using a Jacquard mechanism.

#### **4.2. Barmen lace braiding machine**

described by the stitches, i.e., the basic movements of bobbin pairs. Furthermore, by utilizing various materials and yarn tensions, other desired features such as textures and holes may be

During the formation of lace, the yarns form an X that is identified as either a cross or a twist depending on the direction. Twist is defined as a counter-clockwise motion where the right yarn of each pair is laid over the left yarn. The twist motion pairs stay together on the machine plate. Cross is a clockwise motion worked with two adjacent pairs and the inner pairs are crossed so that the left yarn of the inner pair is laid over the right yarn. The cross pairs are interchanged. In **Figure 2**, the first and fourth yarns remain stationary while the second and third yarns cross multiple times. Then the first and third yarn twists multiple times simultane-

For various reasons details of the Barmen braiding machine have not been readily available, and known only by a select few. The complexity of these machines tended to require specialized operational expertise as well. Thus, expertise with these machines tended to be concentrated within the immediate geographic region of the machine origin. In the case of the Barmen lace braiding machine, the region was Barmen—an industrial city that later merged with Wuppertal, Germany. Publications, outside of textile trade literature and patent literature, related to the Barmen lace braiding machine are scarce. The descriptions found in the patent literature are inadequate for interested audiences outside those skilled in the art. In general, the lace braiding industry had many trade secrets where knowledge of pattern design, machinery, and operations was confined to an esoteric group of practitioners.

imparted to the lace.

62 Engineered Fabrics

**4.1. Barmen lace**

**Figure 2.** Basic stitches of lace.

**4. Stitches of braided lace**

ously with the second and fourth yarns.

**Figure 3** shows the general structure of a Barmen lace braiding machine. By comparison, this machine is significantly smaller than those other lace formation technologies. The basic components of the Maypole braider are also found in the Barmen braiding machine including frame, spur gear train, spindles, and take-up device. However, the Barmen machine employs more advanced features. The primary difference is the versatility of the driver plates (i.e., horn gears) which can be turned on and off as stipulated by operational rules. **Figure 4** is a schematic view of the top of a Barmen lace braiding machine. The even numbered driver plates turn clockwise and the odd numbered driver plates turn counter-clockwise. The even cycle must finish and the spindles or carriers stop before the odd cycle can begin.

**Figure 3.** Barmen lace braiding machine circa 1920 [14].

and computerized design to operate seamlessly without Jacquard punch paper. The electronic control eliminated the need for a mechanical Jacquard mechanism. Improvements in machine materials have increased the wear resistance and life of components. Certain mechanical features of the modern lace braiding machine protect the components and its lace product during production. For example, if the yarn breaks during production, the machine will automatically shut off as the bobbin carrier shorts an electrical switch so that the lace fabric can be saved and the broken yarn can be repaired by simply tying a knot. If this feature were not available, each time a yarn broke, the whole lace fabric would have to be discarded. A second feature is the construction of clutches out of a low-cost plastic material. If certain components fail to function perfectly, the clutch will fail before machine damage occurs. These inexpensive clutches can be replaced relatively easily and quickly. These two protective features are essential for industrial lace braiding but they limit the

Lace Braiding Machines for Composite Preform Manufacture

http://dx.doi.org/10.5772/intechopen.82256

65

Presently many of the modern machines are produced by Asian manufacturers who are in proximity to the textile manufacturing locations, although the Krenzler Company still manufactures lace braiding machines in Germany [16]. The machine evaluated in this research is manufactured in South Korea and clearly has its engineering origins from the Barmen lace machine. Considering improvements in the Barmen lace braiding machine during the last 30 years and the fact that many lace braiding machines are now manufactured outside of Germany, we refer to these machines as modern lace braiding machines. We acknowledge

**Figure 5** is an engineering rendering of the modern lace braiding machine evaluated during this research. **Figure 6** illustrates the bobbin spindle actuation assembly. Spindle cradles are used to move yarns with the driving plates. The solenoid actuates the plastic cam which in turn lifts the plastic fork and plastic clutch and engages the driver plate allowing the spur gear to rotate the spindle cradles and perform the basic cross and twist motions on the yarns. After 180 degrees of rotation, the cam pushes against the inactive solenoid and a compression spring forces the fork and clutch to the resting position while spindle cradles and bobbins

Another important component is the bobbin spindle. Commonly referred to as carriers, they control the tension in the braiding yarn as well as allowing the release of new material during braiding. See **Figure 7** for the following operational details. The yarn is unwound from the bobbin and passed through an initial eyelet making a 90-degree bend where it continues until a second eyelet is located which also requires a 90-degree bend toward the spindle center where another 90 degree turn over a ratcheting pawl is required. The yarn now travels down the center of the spindle tube i.e. bobbin axis of revolution where a tension spring with eyelet requires a 180 degree turn. Finally, the yarn moves up the tube where a final ceramic eyelet

that the modern lace braiding machines originated from the Barmen lace machines.

size and type of yarn that can be used.

remain stationary.

**5.1. Bobbin spindles (carriers)**

allows the yarn to reach the fabric formation zone.

**Figure 4.** Schematic view of lace braiding machine.

Another notable difference of the Barmen lace braiding machine is the beat-up mechanism. This mechanism is akin to the weaving machine reed used to control fabric density. The beatup mechanism is found in the center of the machine and consists of a dome with slits to allow reciprocating action of knife blades to compact the yarns following the corresponding beating motion. The blades are deployed as even and odd groups, according to the driver plate and spindle motions. These important advances over the Maypole braiding machine provide the ability to produce complex and irregular fabric structures.

The driver plates are positioned as a series of overlapping circles about the machine radius. The driver plate geometry is symmetric about two orthogonal axes with concave and convex regions. For a plate to rotate adjacent plates are required to remain stationary. Adjacent concave regions precisely permit the moving convex spindle cradle to pass without interference. This motion serves as the primary mechanism for imparting motion to the spindles and ultimately the yarn. In the same way as the traditional braiding machine, two different motions are required to pass a spindle.

#### **4.3. Known materials used**

Lace machines have been employed with a variety of materials, both natural and synthetic fibers, in the production of fancy lace and other apparel products. Marenzana [15] describes the use of Rayon fiber with lace braiding machines. Surface fiber treatments, known as sizing, may improve the lace braiding process as well as resin-fiber compatibility in subsequent composite manufacture. The use of high performance fibers such as those commonly found in composite materials has not been reported in the literature.
